Listen for wifi AP state changes.

We won't necessarily receive a connectivity change event when the wifi AP is enabled.
Log active network info.
2026-02-12 18:59:06 +01:00 · 2018-03-26 17:19:17 +01:00 · 2018-03-26 11:49:03 +01:00 · 2018-03-22 17:41:07 +00:00
362 changed files with 9024 additions and 15330 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -20,7 +20,6 @@ local.properties
 .idea/*
 !.idea/runConfigurations/
 !.idea/codeStyleSettings.xml
 !.idea/codeStyles
 .gradle
 build/
 *.iml
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -8,6 +8,8 @@ cache:
 before_script:
  - set -e
  - export GRADLE_USER_HOME=$PWD/.gradle
  # Accept the license for the Android build tools
  - echo y | /opt/android-sdk/tools/bin/sdkmanager "build-tools;26.0.2"
  # Download OpenJDK 6 so we can compile against its standard library
  - JDK_FILE=openjdk-6-jre-headless_6b38-1.13.10-1~deb7u1_amd64.deb
  - if [ ! -d openjdk ]
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -1,261 +0,0 @@
 <component name="ProjectCodeStyleConfiguration">
  <code_scheme name="Project" version="173">
    <option name="RIGHT_MARGIN" value="100" />
    <AndroidXmlCodeStyleSettings>
      <option name="USE_CUSTOM_SETTINGS" value="true" />
    </AndroidXmlCodeStyleSettings>
    <JavaCodeStyleSettings>
      <option name="ANNOTATION_PARAMETER_WRAP" value="1" />
      <option name="CLASS_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99" />
      <option name="NAMES_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99" />
      <option name="PACKAGES_TO_USE_IMPORT_ON_DEMAND">
        <value />
      </option>
      <option name="IMPORT_LAYOUT_TABLE">
        <value>
          <package name="android" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="com" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="junit" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="net" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="org" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="java" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="javax" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="" withSubpackages="true" static="false" />
          <emptyLine />
          <package name="" withSubpackages="true" static="true" />
          <emptyLine />
        </value>
      </option>
      <option name="JD_ALIGN_PARAM_COMMENTS" value="false" />
      <option name="JD_ALIGN_EXCEPTION_COMMENTS" value="false" />
    </JavaCodeStyleSettings>
    <Objective-C-extensions>
      <file>
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
      </file>
      <class>
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
      </class>
      <extensions>
        <pair source="cpp" header="h" fileNamingConvention="NONE" />
        <pair source="c" header="h" fileNamingConvention="NONE" />
      </extensions>
    </Objective-C-extensions>
    <XML>
      <option name="XML_LEGACY_SETTINGS_IMPORTED" value="true" />
    </XML>
    <codeStyleSettings language="Groovy">
      <indentOptions>
        <option name="USE_TAB_CHARACTER" value="true" />
        <option name="SMART_TABS" value="true" />
      </indentOptions>
    </codeStyleSettings>
    <codeStyleSettings language="JAVA">
      <option name="RIGHT_MARGIN" value="80" />
      <option name="ALIGN_MULTILINE_PARAMETERS" value="false" />
      <option name="ALIGN_MULTILINE_RESOURCES" value="false" />
      <option name="ALIGN_MULTILINE_FOR" value="false" />
      <option name="SPACE_BEFORE_ARRAY_INITIALIZER_LBRACE" value="true" />
      <option name="CALL_PARAMETERS_WRAP" value="1" />
      <option name="METHOD_PARAMETERS_WRAP" value="1" />
      <option name="RESOURCE_LIST_WRAP" value="1" />
      <option name="EXTENDS_LIST_WRAP" value="1" />
      <option name="THROWS_LIST_WRAP" value="1" />
      <option name="EXTENDS_KEYWORD_WRAP" value="1" />
      <option name="THROWS_KEYWORD_WRAP" value="1" />
      <option name="METHOD_CALL_CHAIN_WRAP" value="1" />
      <option name="BINARY_OPERATION_WRAP" value="1" />
      <option name="TERNARY_OPERATION_WRAP" value="1" />
      <option name="FOR_STATEMENT_WRAP" value="1" />
      <option name="ARRAY_INITIALIZER_WRAP" value="1" />
      <option name="ASSIGNMENT_WRAP" value="1" />
      <option name="ASSERT_STATEMENT_WRAP" value="1" />
      <option name="PARAMETER_ANNOTATION_WRAP" value="1" />
      <option name="VARIABLE_ANNOTATION_WRAP" value="1" />
      <option name="ENUM_CONSTANTS_WRAP" value="1" />
      <indentOptions>
        <option name="USE_TAB_CHARACTER" value="true" />
        <option name="SMART_TABS" value="true" />
      </indentOptions>
    </codeStyleSettings>
    <codeStyleSettings language="XML">
      <option name="FORCE_REARRANGE_MODE" value="1" />
      <indentOptions>
        <option name="CONTINUATION_INDENT_SIZE" value="4" />
        <option name="USE_TAB_CHARACTER" value="true" />
        <option name="SMART_TABS" value="true" />
      </indentOptions>
      <arrangement>
        <rules>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>xmlns:android</NAME>
                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>xmlns:.*</NAME>
                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:id</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:name</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>name</NAME>
                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>style</NAME>
                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*</NAME>
                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:layout_width</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:layout_height</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:layout_.*</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:width</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*:height</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*</NAME>
                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
          <section>
            <rule>
              <match>
                <AND>
                  <NAME>.*</NAME>
                  <XML_NAMESPACE>.*</XML_NAMESPACE>
                </AND>
              </match>
              <order>BY_NAME</order>
            </rule>
          </section>
        </rules>
      </arrangement>
    </codeStyleSettings>
  </code_scheme>
 </component>
--- a/.idea/codeStyles/codeStyleConfig.xml
+++ b/.idea/codeStyles/codeStyleConfig.xml
@@ -1,5 +0,0 @@
 <component name="ProjectCodeStyleConfiguration">
  <state>
    <option name="USE_PER_PROJECT_SETTINGS" value="true" />
  </state>
 </component>
--- a/bramble-android/build.gradle
+++ b/bramble-android/build.gradle
@@ -1,21 +1,19 @@
 import de.undercouch.gradle.tasks.download.Download
 import de.undercouch.gradle.tasks.download.Verify
 import java.security.NoSuchAlgorithmException
 apply plugin: 'com.android.library'
 apply plugin: 'witness'
 apply plugin: 'de.undercouch.download'
 android {
 	compileSdkVersion 27
-	buildToolsVersion '27.0.3'
+	buildToolsVersion '26.0.2'
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 10002
+		versionCode 1700
-		versionName "1.0.2"
+		versionName "0.17.0"
 		consumerProguardFiles 'proguard-rules.txt'
 	}
@@ -36,79 +34,23 @@ dependencies {
 dependencyVerification {
 	verify = [
-			'com.android.tools.analytics-library:protos:26.1.2:protos-26.1.2.jar:52672a0b42b572a06aecc3535d5068eb46c0e15d129b9f1085d3c16a1da5cdbb',
+			'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
 			'com.android.tools.analytics-library:shared:26.1.2:shared-26.1.2.jar:5c7e0eda18c6f87feeb83628c707e8aaa3298b41fb72e38efe31ad1675f9e8e9',
 			'com.android.tools.analytics-library:tracker:26.1.2:tracker-26.1.2.jar:06f97aa0adf44ffb06f8681c6a79d9be153a08f61d21eddc42b8d3db96df4282',
 			'com.android.tools.build:apksig:3.1.2:apksig-3.1.2.jar:40696a4559124d1d57873d208857eee059d48859239d569c7d18374ac644a8be',
 			'com.android.tools.build:builder-model:3.1.2:builder-model-3.1.2.jar:d49bfa2a135c9562b6ca7aa4342036cfa1582c7074c2d1d93d1dae8b3a134e17',
 			'com.android.tools.build:builder-test-api:3.1.2:builder-test-api-3.1.2.jar:dfe2a50b740d41b11189101062434d4283d18647e89a492ad51710c719363e9f',
 			'com.android.tools.build:builder:3.1.2:builder-3.1.2.jar:b60f825a42e2efe8433619fbc759f3d9effecab718279048d36881188ceb1d14',
 			'com.android.tools.build:gradle-api:3.1.2:gradle-api-3.1.2.jar:e58bcc5b893e4583ab0f5c8ef89c4dbcce202b405a9d7fcc116d21e5357d4893',
 			'com.android.tools.build:manifest-merger:26.1.2:manifest-merger-26.1.2.jar:9c61c27ea5266573107b954acf1216d398f4d7e7ae6fad6409d6b2b767eb091c',
 			'com.android.tools.ddms:ddmlib:26.1.2:ddmlib-26.1.2.jar:18a2a5fbef36882f07d03c2b9e59eba05cf8248177bf5cbff736e4b582804c44',
 			'com.android.tools.external.com-intellij:intellij-core:26.1.2:intellij-core-26.1.2.jar:37c5acf279f1ae3e85b1a5be3c9f15f43bde7b08f978eefefffb9c4035760c52',
 			'com.android.tools.external.com-intellij:kotlin-compiler:26.1.2:kotlin-compiler-26.1.2.jar:152df0bee7580326c77316b669a9d96e3b09efb1d45f545dce4147271b0b8944',
 			'com.android.tools.external.org-jetbrains:uast:26.1.2:uast-26.1.2.jar:02d39582206d3f5fc0a6cb18bfd9e8b9f9c1acb805ec6dac08b4e3a56849d279',
 			'com.android.tools.layoutlib:layoutlib-api:26.1.2:layoutlib-api-26.1.2.jar:20220039fcc7d799f928153beff862e704457c0f55ab44258f3745ebeb662b4f',
 			'com.android.tools.lint:lint-api:26.1.2:lint-api-26.1.2.jar:e1d5b62b870a7c566e9877a6b96b27784a4d713f8caa07fdcb4705d47a40a1d9',
 			'com.android.tools.lint:lint-checks:26.1.2:lint-checks-26.1.2.jar:211e2afd58504372385d71b1e5be982c2b5121ab6fee1c04ddabeb75a8729e07',
 			'com.android.tools.lint:lint-gradle-api:26.1.2:lint-gradle-api-26.1.2.jar:71284f2a8b03c3e55c94511c9eb36f8184fbb85324325fc6b78abf5183f03d90',
 			'com.android.tools.lint:lint-gradle:26.1.2:lint-gradle-26.1.2.jar:855f0c82b7fc690df1b7319c0774f7517f7f8f5dd4eee1f6077dcf50e07c6240',
 			'com.android.tools.lint:lint-kotlin:26.1.2:lint-kotlin-26.1.2.jar:1e591f70bcbbc11569720a9bbcca2bc1f3d4f789f01f40f642848d920643d484',
 			'com.android.tools.lint:lint:26.1.2:lint-26.1.2.jar:93736c62e9f1976998c2b4aa716aea0734cdb162d05502f4af7292654aedb182',
 			'com.android.tools:annotations:26.1.2:annotations-26.1.2.jar:72773dcaf5c4ccca828e3c8467f1b78a8a00b3cc5f8ad1aab88fcf9379928018',
 			'com.android.tools:common:26.1.2:common-26.1.2.jar:ea4320f0c17dcbc4491896bb705c4d25ec08bd62ef02ab0579fe154e75e788e6',
 			'com.android.tools:dvlib:26.1.2:dvlib-26.1.2.jar:1187aa4fb666595c96c4deb6bc0e0f4b7e396bde9f6243330b49a232946130ea',
 			'com.android.tools:repository:26.1.2:repository-26.1.2.jar:8b86e512ad6d32bd76989451eefe2b271f5efce6d4d65ecb173afaf14606e01a',
 			'com.android.tools:sdk-common:26.1.2:sdk-common-26.1.2.jar:23584720a60a21cdcb5b1ec10269e3013789d6805d153cc696c39ec7ce251896',
 			'com.android.tools:sdklib:26.1.2:sdklib-26.1.2.jar:d3870fafc59ab8efa70d3f9649f40ee299c8ec5b58377b06e8853d7272a5bf4e',
 			'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
 			'com.google.code.gson:gson:2.7:gson-2.7.jar:2d43eb5ea9e133d2ee2405cc14f5ee08951b8361302fdd93494a3a997b508d32',
 			'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
 			'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
 			'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
 			'com.google.errorprone:error_prone_annotations:2.0.18:error_prone_annotations-2.0.18.jar:cb4cfad870bf563a07199f3ebea5763f0dec440fcda0b318640b1feaa788656b',
 			'com.google.guava:guava:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
-			'com.google.guava:guava:22.0:guava-22.0.jar:1158e94c7de4da480873f0b4ab4a1da14c0d23d4b1902cc94a58a6f0f9ab579e',
+			'com.h2database:h2:1.4.192:h2-1.4.192.jar:225b22e9857235c46c93861410b60b8c81c10dc8985f4faf188985ba5445126c',
-			'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
+			'com.madgag.spongycastle:core:1.58.0.0:core-1.58.0.0.jar:199617dd5698c5a9312b898c0a4cec7ce9dd8649d07f65d91629f58229d72728',
 			'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
 			'com.google.protobuf:protobuf-java:3.4.0:protobuf-java-3.4.0.jar:dce7e66b32456a1b1198da0caff3a8acb71548658391e798c79369241e6490a4',
 			'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
 			'com.squareup:javawriter:2.5.0:javawriter-2.5.0.jar:fcfb09fb0ea0aa97d3cfe7ea792398081348e468f126b3603cb3803f240197f0',
 			'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
 			'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
 			'com.sun.xml.fastinfoset:FastInfoset:1.2.13:FastInfoset-1.2.13.jar:27a77db909f3c2833c0b1a37c55af1db06045118ad2eed96ce567b6632bce038',
 			'commons-codec:commons-codec:1.6:commons-codec-1.6.jar:54b34e941b8e1414bd3e40d736efd3481772dc26db3296f6aa45cec9f6203d86',
 			'commons-logging:commons-logging:1.1.1:commons-logging-1.1.1.jar:ce6f913cad1f0db3aad70186d65c5bc7ffcc9a99e3fe8e0b137312819f7c362f',
 			'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
 			'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
 			'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
-			'javax.xml.bind:jaxb-api:2.2.12-b140109.1041:jaxb-api-2.2.12-b140109.1041.jar:b5e60cd8b7b5ff01ce4a74c5dd008f4fbd14ced3495d0b47b85cfedc182211f2',
+			'net.i2p.crypto:eddsa:0.2.0:eddsa-0.2.0.jar:a7cb1b85c16e2f0730b9204106929a1d9aaae1df728adc7041a8b8b605692140',
-			'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
+			'org.bitlet:weupnp:0.1.4:weupnp-0.1.4.jar:88df7e6504929d00bdb832863761385c68ab92af945b04f0770b126270a444fb',
-			'net.sf.kxml:kxml2:2.3.0:kxml2-2.3.0.jar:f264dd9f79a1fde10ce5ecc53221eff24be4c9331c830b7d52f2f08a7b633de2',
+			'org.jacoco:org.jacoco.agent:0.7.4.201502262128:org.jacoco.agent-0.7.4.201502262128-runtime.jar:e357a0f1d573c2f702a273992b1b6cb661734f66311854efb3778a888515c5b5',
-			'org.apache.commons:commons-compress:1.12:commons-compress-1.12.jar:2c1542faf343185b7cab9c3d55c8ae5471d6d095d3887a4adefdbdf2984dc0b6',
+			'org.jacoco:org.jacoco.agent:0.7.4.201502262128:org.jacoco.agent-0.7.4.201502262128.jar:47b4bec6df11a1118da3953da8b9fa1e7079d6fec857faa1a3cf912e53a6fd4e',
-			'org.apache.httpcomponents:httpclient:4.2.6:httpclient-4.2.6.jar:362e9324ee7c697e21279e20077b52737ddef3f1b2c1a7abe5ad34b465145550',
+			'org.jacoco:org.jacoco.ant:0.7.4.201502262128:org.jacoco.ant-0.7.4.201502262128.jar:013ce2a68ba57a3c59215ae0dec4df3498c078062a38c3b94c841fc14450f283',
-			'org.apache.httpcomponents:httpcore:4.2.5:httpcore-4.2.5.jar:e5e82da4cc66c8d917bbf743e3c0752efe8522735e7fc9dbddb65bccea81cfe9',
+			'org.jacoco:org.jacoco.core:0.7.4.201502262128:org.jacoco.core-0.7.4.201502262128.jar:ec4c74554312fac5116350164786f91b35c9e082fa4ea598bfa42b5db05d7abb',
-			'org.apache.httpcomponents:httpmime:4.1:httpmime-4.1.jar:31629566148e8a47688ae43b420abc3ecd783ed15b33bebc00824bf24c9b15aa',
+			'org.jacoco:org.jacoco.report:0.7.4.201502262128:org.jacoco.report-0.7.4.201502262128.jar:7a3554c605e088e7e323b1084656243f0444fa353e2f2dee1f1a4204eb64ff09',
-			'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
+			'org.ow2.asm:asm-debug-all:5.0.1:asm-debug-all-5.0.1.jar:4734de5b515a454b0096db6971fb068e5f70e6f10bbee2b3bd2fdfe5d978ed57',
 			'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
 			'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
 			'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
 			'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
 			'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
 			'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
 			'org.jetbrains.kotlin:kotlin-reflect:1.2.0:kotlin-reflect-1.2.0.jar:4f48a872bad6e4d9c053f4ad610d11e4012ad7e58dc19a03dd5eb811f36069dd',
 			'org.jetbrains.kotlin:kotlin-stdlib-jre7:1.2.0:kotlin-stdlib-jre7-1.2.0.jar:c7a20fb951d437797afe8980aff6c1e5a03f310c661ba58ba1d4fa90cb0f2926',
 			'org.jetbrains.kotlin:kotlin-stdlib-jre8:1.2.0:kotlin-stdlib-jre8-1.2.0.jar:633524eee6ef1941f7cb1dab7ee3927b0a221ceee9047aeb5515f4cbb990c82a',
 			'org.jetbrains.kotlin:kotlin-stdlib:1.2.0:kotlin-stdlib-1.2.0.jar:05cfd9f5ac0b41910703a8925f7211a495909b27a2ffdd1c5106f1689aeafcd4',
 			'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
 			'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
 			'org.jvnet.staxex:stax-ex:1.7.7:stax-ex-1.7.7.jar:a31ff7d77163c0deb09e7fee59ad35ae44c2cee2cc8552a116ccd1583d813fb4',
 			'org.ow2.asm:asm-analysis:5.1:asm-analysis-5.1.jar:a34658f5c5de4b573eef21131cc32cc25f7b66407944f312b28ec2e56abb1fa9',
 			'org.ow2.asm:asm-commons:5.1:asm-commons-5.1.jar:97b3786e1f55e74bddf8ad102bf50e33bbcbc1f6b7fd7b36f0bbbb25cd4981be',
 			'org.ow2.asm:asm-tree:5.1:asm-tree-5.1.jar:c0de2bbc4cb8297419659813ecd4ed1d077ed1dd5c1f5544cc5143e493e84c10',
 			'org.ow2.asm:asm-util:5.1:asm-util-5.1.jar:ee032c39ae5e3cd099148fbba9a2124f9ed613e5cb93e03ee0fa8808ce364040',
 			'org.ow2.asm:asm:5.1:asm-5.1.jar:d2da399a9967c69f0a21739256fa79d284222c223082cacadc17372244764b54',
 	]
 }
@@ -125,68 +67,30 @@ def torBinaries = [
 		"geoip"      : '8239b98374493529a29096e45fc5877d4d6fdad0146ad8380b291f90d61484ea'
 ]
-def verifyOrDeleteBinary(name, chksum, alreadyVerified) {
+def downloadBinary(name) {
-	return tasks.create("verifyOrDeleteBinary${name}", VerifyOrDelete) {
+	return tasks.create("downloadBinary${name}", Download) {
 		src "${torBinaryDir}/${name}.zip"
 		algorithm 'SHA-256'
 		checksum chksum
 		result alreadyVerified
 		onlyIf {
 			src.exists()
 		}
 	}
 }
 def downloadBinary(name, chksum, alreadyVerified) {
 	return tasks.create([
 			name: "downloadBinary${name}",
 			type: Download,
 			dependsOn: verifyOrDeleteBinary(name, chksum, alreadyVerified)]) {
 		src "${torDownloadUrl}${name}.zip"
 				.replace('tor_', "tor-${torVersion}-")
 				.replace('geoip', "geoip-${geoipVersion}")
 				.replaceAll('_', '-')
 		dest "${torBinaryDir}/${name}.zip"
-		onlyIf {
+		onlyIfNewer true
 			!dest.exists()
 		}
 	}
 }
 def verifyBinary(name, chksum) {
 	boolean[] alreadyVerified = [false]
 	return tasks.create([
 			name     : "verifyBinary${name}",
 			type     : Verify,
-			dependsOn: downloadBinary(name, chksum, alreadyVerified)]) {
+			dependsOn: downloadBinary(name)]) {
 		src "${torBinaryDir}/${name}.zip"
 		algorithm 'SHA-256'
 		checksum chksum
 		onlyIf {
 			!alreadyVerified[0]
 		}
 	}
 }
 project.afterEvaluate {
-	torBinaries.every { name, checksum ->
+	torBinaries.every { key, value ->
-		preBuild.dependsOn.add(verifyBinary(name, checksum))
+		preBuild.dependsOn.add(verifyBinary(key, value))
 	}
 }
 class VerifyOrDelete extends Verify {
 	boolean[] result
 	@TaskAction
 	@Override
 	void verify() throws IOException, NoSuchAlgorithmException {
 		try {
 			super.verify()
 			result[0] = true
 		} catch (Exception e) {
 			println "${src} failed verification - deleting"
 			src.delete()
 		}
 	}
 }
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java
@@ -48,7 +48,7 @@ public class AndroidPluginModule {
 				appContext, locationUtils, reporter, eventBus,
 				torSocketFactory, backoffFactory);
 		DuplexPluginFactory lan = new AndroidLanTcpPluginFactory(ioExecutor,
-				scheduler, backoffFactory, appContext);
+				backoffFactory, appContext);
 		Collection<DuplexPluginFactory> duplex =
 				Arrays.asList(bluetooth, tor, lan);
 		@NotNullByDefault
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java
@@ -55,12 +55,10 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	// Non-null if the plugin started successfully
 	private volatile BluetoothAdapter adapter = null;
-	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
+	AndroidBluetoothPlugin(Executor ioExecutor, AndroidExecutor androidExecutor,
 			Executor ioExecutor, AndroidExecutor androidExecutor,
 			Context appContext, SecureRandom secureRandom, Backoff backoff,
 			DuplexPluginCallback callback, int maxLatency) {
-		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
+		super(ioExecutor, secureRandom, backoff, callback, maxLatency);
 				maxLatency);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 	}
@@ -156,8 +154,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	}
 	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-		return new AndroidBluetoothTransportConnection(this,
+		return new AndroidBluetoothTransportConnection(this, s);
 				connectionLimiter, s);
 	}
 	@Override
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPluginFactory.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPluginFactory.java
@@ -59,13 +59,11 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
 				new BluetoothConnectionLimiterImpl();
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
+		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(ioExecutor,
-				connectionLimiter, ioExecutor, androidExecutor, appContext,
+				androidExecutor, appContext, secureRandom, backoff, callback,
-				secureRandom, backoff, callback, MAX_LATENCY);
+				MAX_LATENCY);
 		eventBus.addListener(plugin);
 		return plugin;
 	}
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothTransportConnection.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothTransportConnection.java
@@ -14,14 +14,10 @@ import java.io.OutputStream;
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 	private final BluetoothConnectionLimiter connectionManager;
 	private final BluetoothSocket socket;
-	AndroidBluetoothTransportConnection(Plugin plugin,
+	AndroidBluetoothTransportConnection(Plugin plugin, BluetoothSocket socket) {
 			BluetoothConnectionLimiter connectionManager,
 			BluetoothSocket socket) {
 		super(plugin);
 		this.connectionManager = connectionManager;
 		this.socket = socket;
 	}
@@ -37,10 +33,6 @@ class AndroidBluetoothTransportConnection
 	@Override
 	protected void closeConnection(boolean exception) throws IOException {
-		try {
+		socket.close();
 			socket.close();
 		} finally {
 			connectionManager.connectionClosed(this);
 		}
 	}
 }
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java
@@ -5,84 +5,43 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
 import android.net.Network;
 import android.net.NetworkInfo;
-import android.net.wifi.WifiInfo;
+import android.os.Bundle;
 import android.net.wifi.WifiManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.Socket;
 import java.net.UnknownHostException;
 import java.util.Collection;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.net.SocketFactory;
 import static android.content.Context.CONNECTIVITY_SERVICE;
 import static android.content.Context.WIFI_SERVICE;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.net.wifi.WifiManager.EXTRA_WIFI_STATE;
-import static android.os.Build.VERSION.SDK_INT;
+import static java.util.logging.Level.INFO;
-import static java.util.Collections.emptyList;
+import static org.briarproject.bramble.util.AndroidUtils.logNetworkState;
 import static java.util.Collections.singletonList;
 import static java.util.concurrent.TimeUnit.SECONDS;
@NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin {
-	// See android.net.wifi.WifiManager
+	private static final String WIFI_AP_STATE_ACTION =
 	private static final String WIFI_AP_STATE_CHANGED_ACTION =
 			"android.net.wifi.WIFI_AP_STATE_CHANGED";
 	private static final int WIFI_AP_STATE_ENABLED = 13;
 	private static final byte[] WIFI_AP_ADDRESS_BYTES =
 			{(byte) 192, (byte) 168, 43, 1};
 	private static final InetAddress WIFI_AP_ADDRESS;
 	private static final Logger LOG =
 			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
 	static {
 		try {
 			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
 		} catch (UnknownHostException e) {
 			// Should only be thrown if the address has an illegal length
 			throw new AssertionError(e);
 		}
 	}
 	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final ConnectivityManager connectivityManager;
 	@Nullable
 	private final WifiManager wifiManager;
 	@Nullable
 	private volatile BroadcastReceiver networkStateReceiver = null;
 	private volatile SocketFactory socketFactory;
-	AndroidLanTcpPlugin(Executor ioExecutor, ScheduledExecutorService scheduler,
+	AndroidLanTcpPlugin(Executor ioExecutor, Backoff backoff,
-			Backoff backoff, Context appContext, DuplexPluginCallback callback,
+			Context appContext, DuplexPluginCallback callback, int maxLatency,
-			int maxLatency, int maxIdleTime) {
+			int maxIdleTime) {
 		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
 		this.scheduler = scheduler;
 		this.appContext = appContext;
 		ConnectivityManager connectivityManager = (ConnectivityManager)
 				appContext.getSystemService(CONNECTIVITY_SERVICE);
 		if (connectivityManager == null) throw new AssertionError();
 		this.connectivityManager = connectivityManager;
 		wifiManager = (WifiManager) appContext.getApplicationContext()
 				.getSystemService(WIFI_SERVICE);
 		socketFactory = SocketFactory.getDefault();
 	}
 	@Override
@@ -93,8 +52,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		networkStateReceiver = new NetworkStateReceiver();
 		IntentFilter filter = new IntentFilter();
 		filter.addAction(CONNECTIVITY_ACTION);
-		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
+		filter.addAction(WIFI_AP_STATE_ACTION);
 		appContext.registerReceiver(networkStateReceiver, filter);
 		if (LOG.isLoggable(INFO)) logNetworkState(appContext, LOG);
 	}
 	@Override
@@ -105,92 +65,38 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		tryToClose(socket);
 	}
 	@Override
 	protected Socket createSocket() throws IOException {
 		return socketFactory.createSocket();
 	}
 	@Override
 	protected Collection<InetAddress> getLocalIpAddresses() {
 		// If the device doesn't have wifi, don't open any sockets
 		if (wifiManager == null) return emptyList();
 		// If we're connected to a wifi network, use that network
 		WifiInfo info = wifiManager.getConnectionInfo();
 		if (info != null && info.getIpAddress() != 0)
 			return singletonList(intToInetAddress(info.getIpAddress()));
 		// If we're running an access point, return its address
 		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
 				return singletonList(WIFI_AP_ADDRESS);
 		// No suitable addresses
 		return emptyList();
 	}
 	private InetAddress intToInetAddress(int ip) {
 		byte[] ipBytes = new byte[4];
 		ipBytes[0] = (byte) (ip & 0xFF);
 		ipBytes[1] = (byte) ((ip >> 8) & 0xFF);
 		ipBytes[2] = (byte) ((ip >> 16) & 0xFF);
 		ipBytes[3] = (byte) ((ip >> 24) & 0xFF);
 		try {
 			return InetAddress.getByAddress(ipBytes);
 		} catch (UnknownHostException e) {
 			// Should only be thrown if address has illegal length
 			throw new AssertionError(e);
 		}
 	}
 	// On API 21 and later, a socket that is not created with the wifi
 	// network's socket factory may try to connect via another network
 	private SocketFactory getSocketFactory() {
 		if (SDK_INT < 21) return SocketFactory.getDefault();
 		for (Network net : connectivityManager.getAllNetworks()) {
 			NetworkInfo info = connectivityManager.getNetworkInfo(net);
 			if (info != null && info.getType() == TYPE_WIFI)
 				return net.getSocketFactory();
 		}
 		LOG.warning("Could not find suitable socket factory");
 		return SocketFactory.getDefault();
 	}
 	private class NetworkStateReceiver extends BroadcastReceiver {
 		@Override
 		public void onReceive(Context ctx, Intent i) {
 			if (!running) return;
-			if (isApEnabledEvent(i)) {
+			if (LOG.isLoggable(INFO)) {
-				// The state change may be broadcast before the AP address is
+				if (CONNECTIVITY_ACTION.equals(i.getAction())) {
-				// visible, so delay handling the event
+					LOG.info("Connectivity change");
-				scheduler.schedule(this::handleConnectivityChange, 1, SECONDS);
+					Bundle extras = i.getExtras();
-			} else {
+					if (extras != null) {
-				handleConnectivityChange();
+						LOG.info("Extras:");
 						for (String key : extras.keySet())
 							LOG.info("\t" + key + ": " + extras.get(key));
 					}
 				} else if (WIFI_AP_STATE_ACTION.equals(i.getAction())) {
 					int state = i.getIntExtra(EXTRA_WIFI_STATE, 0);
 					if (state == 13) LOG.info("Wifi AP enabled");
 					else LOG.info("Wifi AP state " + state);
 				}
 				logNetworkState(appContext, LOG);
 			}
-		}
+			Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
-
+			ConnectivityManager cm = (ConnectivityManager) o;
-		private void handleConnectivityChange() {
+			NetworkInfo net = cm.getActiveNetworkInfo();
-			if (!running) return;
+			if (net != null && net.getType() == TYPE_WIFI
-			Collection<InetAddress> addrs = getLocalIpAddresses();
+					&& net.isConnected()) {
-			if (addrs.contains(WIFI_AP_ADDRESS)) {
+				LOG.info("Connected to Wi-Fi");
 				LOG.info("Providing wifi hotspot");
 				// There's no corresponding Network object and thus no way
 				// to get a suitable socket factory, so we won't be able to
 				// make outgoing connections on API 21+ if another network
 				// has internet access
 				socketFactory = SocketFactory.getDefault();
 				if (socket == null || socket.isClosed()) bind();
-			} else if (addrs.isEmpty()) {
+			} else {
-				LOG.info("Not connected to wifi");
+				LOG.info("Not connected to Wi-Fi");
 				socketFactory = SocketFactory.getDefault();
 				tryToClose(socket);
 			} else {
 				LOG.info("Connected to wifi");
 				socketFactory = getSocketFactory();
 				if (socket == null || socket.isClosed()) bind();
 			}
 		}
 		private boolean isApEnabledEvent(Intent i) {
 			return WIFI_AP_STATE_CHANGED_ACTION.equals(i.getAction()) &&
 					i.getIntExtra(EXTRA_WIFI_STATE, 0) == WIFI_AP_STATE_ENABLED;
 		}
 	}
 }
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java
@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
 import javax.annotation.concurrent.Immutable;
@@ -28,15 +27,12 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 	private final Executor ioExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final BackoffFactory backoffFactory;
 	private final Context appContext;
 	public AndroidLanTcpPluginFactory(Executor ioExecutor,
-			ScheduledExecutorService scheduler, BackoffFactory backoffFactory,
+			BackoffFactory backoffFactory, Context appContext) {
 			Context appContext) {
 		this.ioExecutor = ioExecutor;
 		this.scheduler = scheduler;
 		this.backoffFactory = backoffFactory;
 		this.appContext = appContext;
 	}
@@ -55,7 +51,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new AndroidLanTcpPlugin(ioExecutor, scheduler, backoff,
+		return new AndroidLanTcpPlugin(ioExecutor, backoff, appContext,
-				appContext, callback, MAX_LATENCY, MAX_IDLE_TIME);
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 	}
 }
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java
@@ -16,7 +16,6 @@ import android.os.PowerManager;
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -64,6 +63,8 @@ import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
@@ -110,7 +111,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(TorPlugin.class.getName());
-	private final Executor ioExecutor, connectionStatusExecutor;
+	private final Executor ioExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final LocationUtils locationUtils;
@@ -124,6 +125,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final File torDirectory, torFile, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final PowerManager.WakeLock wakeLock;
 	private final Lock connectionStatusLock;
 	private final AtomicReference<Future<?>> connectivityCheck =
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -165,9 +167,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		// This tag will prevent Huawei's powermanager from killing us.
 		wakeLock = pm.newWakeLock(PARTIAL_WAKE_LOCK, "LocationManagerService");
 		wakeLock.setReferenceCounted(false);
-		// Don't execute more than one connection status check at a time
+		connectionStatusLock = new ReentrantLock();
 		connectionStatusExecutor = new PoliteExecutor("TorPlugin",
 				ioExecutor, 1);
 	}
 	@Override
@@ -697,46 +697,55 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 	private void updateConnectionStatus() {
-		connectionStatusExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			if (!running) return;
 			Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
 			ConnectivityManager cm = (ConnectivityManager) o;
 			NetworkInfo net = cm.getActiveNetworkInfo();
 			boolean online = net != null && net.isConnected();
 			boolean wifi = online && net.getType() == TYPE_WIFI;
 			String country = locationUtils.getCurrentCountry();
 			boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(
 					country);
 			Settings s = callback.getSettings();
 			int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
 				if ("".equals(country)) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
 			}
 			try {
-				if (!online) {
+				connectionStatusLock.lock();
-					LOG.info("Disabling network, device is offline");
+				updateConnectionStatusLocked();
-					enableNetwork(false);
+			} finally {
-				} else if (blocked) {
+				connectionStatusLock.unlock();
 					LOG.info("Disabling network, country is blocked");
 					enableNetwork(false);
 				} else if (network == PREF_TOR_NETWORK_NEVER
 						|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
 					LOG.info("Disabling network due to data setting");
 					enableNetwork(false);
 				} else {
 					LOG.info("Enabling network");
 					enableNetwork(true);
 				}
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			}
 		});
 	}
 	// Locking: connectionStatusLock
 	private void updateConnectionStatusLocked() {
 		Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
 		ConnectivityManager cm = (ConnectivityManager) o;
 		NetworkInfo net = cm.getActiveNetworkInfo();
 		boolean online = net != null && net.isConnected();
 		boolean wifi = online && net.getType() == TYPE_WIFI;
 		String country = locationUtils.getCurrentCountry();
 		boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(country);
 		Settings s = callback.getSettings();
 		int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("Online: " + online + ", wifi: " + wifi);
 			if ("".equals(country)) LOG.info("Country code unknown");
 			else LOG.info("Country code: " + country);
 		}
 		try {
 			if (!online) {
 				LOG.info("Disabling network, device is offline");
 				enableNetwork(false);
 			} else if (blocked) {
 				LOG.info("Disabling network, country is blocked");
 				enableNetwork(false);
 			} else if (network == PREF_TOR_NETWORK_NEVER
 					|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
 				LOG.info("Disabling network due to data setting");
 				enableNetwork(false);
 			} else {
 				LOG.info("Enabling network");
 				enableNetwork(true);
 			}
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 		}
 	}
 	private void scheduleConnectionStatusUpdate() {
 		Future<?> newConnectivityCheck =
 				scheduler.schedule(this::updateConnectionStatus, 1, MINUTES);
@@ -778,7 +787,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		private synchronized void enableNetwork(boolean enable) {
 			networkEnabled = enable;
-			if (!enable) circuitBuilt = false;
+			circuitBuilt = false;
 		}
 		private synchronized boolean isConnected() {
--- a/bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java
@@ -1,18 +1,41 @@
 package org.briarproject.bramble.util;
 import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.Network;
 import android.net.NetworkInfo;
 import android.net.wifi.WifiInfo;
 import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.provider.Settings;
 import java.io.File;
 import java.net.InetAddress;
 import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import static android.content.Context.CONNECTIVITY_SERVICE;
 import static android.content.Context.MODE_PRIVATE;
 import static android.content.Context.WIFI_SERVICE;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.net.NetworkInterface.getNetworkInterfaces;
 import static java.util.Collections.list;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.StringUtils.ipToString;
 import static org.briarproject.bramble.util.StringUtils.toHexString;
@SuppressLint("HardwareIds")
 public class AndroidUtils {
 	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
@@ -23,7 +46,7 @@ public class AndroidUtils {
 	@SuppressWarnings("deprecation")
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
-		if (Build.VERSION.SDK_INT >= 21) {
+		if (SDK_INT >= 21) {
 			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);
@@ -67,4 +90,123 @@ public class AndroidUtils {
 	public static File getReportDir(Context ctx) {
 		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
 	}
 	public static void logNetworkState(Context ctx, Logger logger) {
 		if (!logger.isLoggable(INFO)) return;
 		Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
 		if (o == null) throw new AssertionError();
 		ConnectivityManager cm = (ConnectivityManager) o;
 		o = ctx.getApplicationContext().getSystemService(WIFI_SERVICE);
 		if (o == null) throw new AssertionError();
 		WifiManager wm = (WifiManager) o;
 		StringBuilder s = new StringBuilder();
 		logWifiInfo(s, wm.getConnectionInfo());
 		logNetworkInfo(s, cm.getActiveNetworkInfo(), true);
 		if (SDK_INT >= 21) {
 			for (Network network : cm.getAllNetworks())
 				logNetworkInfo(s, cm.getNetworkInfo(network), false);
 		} else {
 			for (NetworkInfo info : cm.getAllNetworkInfo())
 				logNetworkInfo(s, info, false);
 		}
 		try {
 			for (NetworkInterface iface : list(getNetworkInterfaces()))
 				logNetworkInterface(s, iface);
 		} catch (SocketException e) {
 			logger.log(WARNING, e.toString(), e);
 		}
 		logger.log(INFO, s.toString());
 	}
 	private static void logWifiInfo(StringBuilder s, @Nullable WifiInfo info) {
 		if (info == null) {
 			s.append("Wifi info: null\n");
 			return;
 		}
 		s.append("Wifi info:\n");
 		s.append("\tSSID: ").append(info.getSSID()).append("\n");
 		s.append("\tBSSID: ").append(info.getBSSID()).append("\n");
 		s.append("\tMAC address: ").append(info.getMacAddress()).append("\n");
 		s.append("\tIP address: ")
 				.append(ipToString(info.getIpAddress())).append("\n");
 		s.append("\tSupplicant state: ")
 				.append(info.getSupplicantState()).append("\n");
 		s.append("\tNetwork ID: ").append(info.getNetworkId()).append("\n");
 		s.append("\tLink speed: ").append(info.getLinkSpeed()).append("\n");
 		s.append("\tRSSI: ").append(info.getRssi()).append("\n");
 		if (info.getHiddenSSID()) s.append("\tHidden SSID\n");
 		if (SDK_INT >= 21)
 			s.append("\tFrequency: ").append(info.getFrequency()).append("\n");
 	}
 	private static void logNetworkInfo(StringBuilder s,
 			@Nullable NetworkInfo info, boolean active) {
 		if (info == null) {
 			if (active) s.append("Active network info: null\n");
 			else s.append("Network info: null\n");
 			return;
 		}
 		if (active) s.append("Active network info:\n");
 		else s.append("Network info:\n");
 		s.append("\tType: ").append(info.getTypeName())
 				.append(" (").append(info.getType()).append(")\n");
 		s.append("\tSubtype: ").append(info.getSubtypeName())
 				.append(" (").append(info.getSubtype()).append(")\n");
 		s.append("\tState: ").append(info.getState()).append("\n");
 		s.append("\tDetailed state: ")
 				.append(info.getDetailedState()).append("\n");
 		s.append("\tReason: ").append(info.getReason()).append("\n");
 		s.append("\tExtra info: ").append(info.getExtraInfo()).append("\n");
 		if (info.isAvailable()) s.append("\tAvailable\n");
 		if (info.isConnected()) s.append("\tConnected\n");
 		if (info.isConnectedOrConnecting())
 			s.append("\tConnected or connecting\n");
 		if (info.isFailover()) s.append("\tFailover\n");
 		if (info.isRoaming()) s.append("\tRoaming\n");
 	}
 	private static void logNetworkInterface(StringBuilder s,
 			NetworkInterface iface) throws SocketException {
 		s.append("Network interface:\n");
 		s.append("\tName: ").append(iface.getName()).append("\n");
 		s.append("\tDisplay name: ")
 				.append(iface.getDisplayName()).append("\n");
 		s.append("\tHardware address: ")
 				.append(hexOrNull(iface.getHardwareAddress())).append("\n");
 		if (iface.isLoopback()) s.append("\tLoopback\n");
 		if (iface.isPointToPoint()) s.append("\tPoint-to-point\n");
 		if (iface.isVirtual()) s.append("\tVirtual\n");
 		if (iface.isUp()) s.append("\tUp\n");
 		if (SDK_INT >= 19)
 			s.append("\tIndex: ").append(iface.getIndex()).append("\n");
 		for (InterfaceAddress addr : iface.getInterfaceAddresses()) {
 			s.append("\tInterface address:\n");
 			logInetAddress(s, addr.getAddress());
 			s.append("\t\tPrefix length: ")
 					.append(addr.getNetworkPrefixLength()).append("\n");
 		}
 	}
 	private static void logInetAddress(StringBuilder s, InetAddress addr) {
 		s.append("\t\tAddress: ")
 				.append(hexOrNull(addr.getAddress())).append("\n");
 		s.append("\t\tHost address: ")
 				.append(addr.getHostAddress()).append("\n");
 		if (addr.isLoopbackAddress()) s.append("\t\tLoopback\n");
 		if (addr.isLinkLocalAddress()) s.append("\t\tLink-local\n");
 		if (addr.isSiteLocalAddress()) s.append("\t\tSite-local\n");
 		if (addr.isAnyLocalAddress()) s.append("\t\tAny local (wildcard)\n");
 		if (addr.isMCNodeLocal()) s.append("\t\tMulticast node-local\n");
 		if (addr.isMCLinkLocal()) s.append("\t\tMulticast link-local\n");
 		if (addr.isMCSiteLocal()) s.append("\t\tMulticast site-local\n");
 		if (addr.isMCOrgLocal()) s.append("\t\tMulticast org-local\n");
 		if (addr.isMCGlobal()) s.append("\t\tMulticast global\n");
 	}
 	@Nullable
 	private static String hexOrNull(@Nullable byte[] b) {
 		return b == null ? null : toHexString(b);
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java
@@ -7,8 +7,6 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
@@ -90,10 +88,6 @@ public interface ClientHelper {
 	BdfDictionary toDictionary(byte[] b, int off, int len)
 			throws FormatException;
 	BdfDictionary toDictionary(TransportProperties transportProperties);
 	BdfDictionary toDictionary(Map<TransportId, TransportProperties> map);
 	BdfList toList(byte[] b, int off, int len) throws FormatException;
 	BdfList toList(byte[] b) throws FormatException;
@@ -105,15 +99,8 @@ public interface ClientHelper {
 	byte[] sign(String label, BdfList toSign, byte[] privateKey)
 			throws FormatException, GeneralSecurityException;
-	void verifySignature(byte[] signature, String label, BdfList signed,
+	void verifySignature(String label, byte[] sig, byte[] publicKey,
-			byte[] publicKey) throws FormatException, GeneralSecurityException;
+			BdfList signed) throws FormatException, GeneralSecurityException;
 	Author parseAndValidateAuthor(BdfList author) throws FormatException;
 	TransportProperties parseAndValidateTransportProperties(
 			BdfDictionary properties) throws FormatException;
 	Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupFactory.java
@@ -12,19 +12,19 @@ public interface ContactGroupFactory {
 	/**
 	 * Creates a group that is not shared with any contacts.
 	 */
-	Group createLocalGroup(ClientId clientId, int majorVersion);
+	Group createLocalGroup(ClientId clientId, int clientVersion);
 	/**
 	 * Creates a group for the given client to share with the given contact.
 	 */
-	Group createContactGroup(ClientId clientId, int majorVersion,
+	Group createContactGroup(ClientId clientId, int clientVersion,
 			Contact contact);
 	/**
 	 * Creates a group for the given client to share between the given authors
 	 * identified by their AuthorIds.
 	 */
-	Group createContactGroup(ClientId clientId, int majorVersion,
+	Group createContactGroup(ClientId clientId, int clientVersion,
 			AuthorId authorId1, AuthorId authorId2);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeTask.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeTask.java
@@ -13,9 +13,9 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 public interface ContactExchangeTask {
 	/**
-	 * The current version of the contact exchange protocol.
+	 * The current version of the contact exchange protocol
 	 */
-	byte PROTOCOL_VERSION = 1;
+	int PROTOCOL_VERSION = 0;
 	/**
 	 * Label for deriving Alice's header key from the master secret.
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactId.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactId.java
@@ -6,7 +6,7 @@ import javax.annotation.concurrent.Immutable;
 /**
 * Type-safe wrapper for an integer that uniquely identifies a contact within
- * the scope of the local device.
+ * the scope of a single node.
 */
@Immutable
@NotNullByDefault
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java
@@ -5,7 +5,6 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.util.Collection;
@@ -14,36 +13,26 @@ import java.util.Collection;
 public interface ContactManager {
 	/**
-	 * Registers a hook to be called whenever a contact is added or removed.
+	 * Registers a hook to be called whenever a contact is added.
 	 * This method should be called before
 	 * {@link LifecycleManager#startServices(String)}.
 	 */
-	void registerContactHook(ContactHook hook);
+	void registerAddContactHook(AddContactHook hook);
 	/**
-	 * Stores a contact associated with the given local and remote pseudonyms,
+	 * Registers a hook to be called whenever a contact is removed.
-	 * derives and stores transport keys for each transport, and returns an ID
+	 */
-	 * for the contact.
+	void registerRemoveContactHook(RemoveContactHook hook);
-	 *
+
-	 * @param alice true if the local party is Alice
+	/**
 	 * Stores a contact within the given transaction associated with the given
 	 * local and remote pseudonyms, and returns an ID for the contact.
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
 			SecretKey master, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms
 	 * and returns an ID for the contact.
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
 			boolean verified, boolean active) throws DbException;
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores transport keys for each transport, and returns an ID
+	 * and returns an ID for the contact.
 	 * for the contact.
 	 *
 	 * @param alice true if the local party is Alice
 	 */
 	ContactId addContact(Author remote, AuthorId local,
 			SecretKey master, long timestamp, boolean alice, boolean verified,
@@ -105,10 +94,11 @@ public interface ContactManager {
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
-	interface ContactHook {
+	interface AddContactHook {
 		void addingContact(Transaction txn, Contact c) throws DbException;
 	}
 	interface RemoveContactHook {
 		void removingContact(Transaction txn, Contact c) throws DbException;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/contact/RecordTypes.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/contact/RecordTypes.java
@@ -1,9 +0,0 @@
 package org.briarproject.bramble.api.contact;
 /**
 * Record types for the contact exchange protocol.
 */
 public interface RecordTypes {
 	byte CONTACT_INFO = 0;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java
@@ -67,8 +67,8 @@ public interface CryptoComponent {
 	 * signature created for another purpose
 	 * @return true if the signature was valid, false otherwise.
 	 */
-	boolean verifySignature(byte[] signature, String label, byte[] signed,
+	boolean verify(String label, byte[] signedData, byte[] publicKey,
-			byte[] publicKey) throws GeneralSecurityException;
+			byte[] signature) throws GeneralSecurityException;
 	/**
 	 * Returns the hash of the given inputs. The inputs are unambiguously
@@ -91,18 +91,6 @@ public interface CryptoComponent {
 	 */
 	byte[] mac(String label, SecretKey macKey, byte[]... inputs);
 	/**
 	 * Verifies that the given message authentication code is valid for the
 	 * given secret key and inputs.
 	 *
 	 * @param label a namespaced label indicating the purpose of this MAC, to
 	 * prevent it from being repurposed or colliding with a MAC created for
 	 * another purpose
 	 * @return true if the MAC was valid, false otherwise.
 	 */
 	boolean verifyMac(byte[] mac, String label, SecretKey macKey,
 			byte[]... inputs);
 	/**
 	 * Encrypts and authenticates the given plaintext so it can be written to
 	 * storage. The encryption and authentication keys are derived from the
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoConstants.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoConstants.java
@@ -16,10 +16,4 @@ public interface CryptoConstants {
 	 * The maximum length of a signature in bytes.
 	 */
 	int MAX_SIGNATURE_BYTES = 64;
 	/**
 	 * The length of a MAC in bytes.
 	 */
 	int MAC_BYTES = SecretKey.LENGTH;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/KeyPair.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/KeyPair.java
@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 /**
- * A key pair consisting of a {@link PublicKey} and a {@link PrivateKey}.
+ * A key pair consisting of a {@link PublicKey} and a {@link PrivateKey).
 */
@Immutable
@NotNullByDefault
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/TransportCrypto.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/crypto/TransportCrypto.java
@@ -14,10 +14,9 @@ public interface TransportCrypto {
 	 * rotation period from the given master secret.
 	 *
 	 * @param alice whether the keys are for use by Alice or Bob.
 	 * @param active whether the keys are usable for outgoing streams.
 	 */
 	TransportKeys deriveTransportKeys(TransportId t, SecretKey master,
-			long rotationPeriod, boolean alice, boolean active);
+			long rotationPeriod, boolean alice);
 	/**
 	 * Rotates the given transport keys to the given rotation period. If the
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfDictionary.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfDictionary.java
@@ -24,9 +24,9 @@ public class BdfDictionary extends TreeMap<String, Object> {
 	 * );
 	 * </pre>
 	 */
-	public static BdfDictionary of(Entry<String, ?>... entries) {
+	public static BdfDictionary of(Entry<String, Object>... entries) {
 		BdfDictionary d = new BdfDictionary();
-		for (Entry<String, ?> e : entries) d.put(e.getKey(), e.getValue());
+		for (Entry<String, Object> e : entries) d.put(e.getKey(), e.getValue());
 		return d;
 	}
@@ -34,7 +34,7 @@ public class BdfDictionary extends TreeMap<String, Object> {
 		super();
 	}
-	public BdfDictionary(Map<String, ?> m) {
+	public BdfDictionary(Map<String, Object> m) {
 		super(m);
 	}
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java
@@ -18,8 +18,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
-import org.briarproject.bramble.api.transport.KeySet;
+import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import java.util.Collection;
@@ -104,17 +103,10 @@ public interface DatabaseComponent {
 			throws DbException;
 	/**
-	 * Stores the given transport keys, optionally binding them to the given
+	 * Stores transport keys for a newly added contact.
 	 * contact, and returns a key set ID.
 	 */
-	KeySetId addTransportKeys(Transaction txn, @Nullable ContactId c,
+	void addTransportKeys(Transaction txn, ContactId c, TransportKeys k)
-			TransportKeys k) throws DbException;
+			throws DbException;
 	/**
 	 * Binds the given keys for the given transport to the given contact.
 	 */
 	void bindTransportKeys(Transaction txn, ContactId c, TransportId t,
 			KeySetId k) throws DbException;
 	/**
 	 * Returns true if the database contains the given contact for the given
@@ -136,8 +128,8 @@ public interface DatabaseComponent {
 	/**
 	 * Deletes the message with the given ID. Unlike
-	 * {@link #removeMessage(Transaction, MessageId)}, the message ID,
+	 * {@link #removeMessage(Transaction, MessageId)}, the message ID and any
-	 * dependencies, metadata, and any other associated state are not deleted.
+	 * other associated data are not deleted.
 	 */
 	void deleteMessage(Transaction txn, MessageId m) throws DbException;
@@ -241,8 +233,7 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<Group> getGroups(Transaction txn, ClientId c, int majorVersion)
+	Collection<Group> getGroups(Transaction txn, ClientId c) throws DbException;
 			throws DbException;
 	/**
 	 * Returns the given group's visibility to the given contact, or
@@ -267,14 +258,6 @@ public interface DatabaseComponent {
 	 */
 	Collection<LocalAuthor> getLocalAuthors(Transaction txn) throws DbException;
 	/**
 	 * Returns the IDs of all delivered messages in the given group.
 	 * <p/>
 	 * Read-only.
 	 */
 	Collection<MessageId> getMessageIds(Transaction txn, GroupId g)
 		throws DbException;
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
@@ -319,9 +302,9 @@ public interface DatabaseComponent {
 			throws DbException;
 	/**
-	 * Returns the metadata for any delivered messages in the given group with
+	 * Returns the metadata for any messages in the given group with metadata
-	 * metadata that matches all entries in the given query. If the query is
+	 * that matches all entries in the given query. If the query is empty, the
-	 * empty, the metadata for all delivered messages is returned.
+	 * metadata for all messages is returned.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -337,8 +320,8 @@ public interface DatabaseComponent {
 			throws DbException;
 	/**
-	 * Returns the metadata for the given delivered or pending message.
+	 * Returns the metadata for the given delivered and pending message.
-	 * This is only meant to be used by the ValidationManager.
+	 * This is meant to be only used by the ValidationManager
 	 * <p/>
 	 * Read-only.
 	 */
@@ -346,8 +329,8 @@ public interface DatabaseComponent {
 			throws DbException;
 	/**
-	 * Returns the status of all delivered messages in the given group with
+	 * Returns the status of all messages in the given group with respect to
-	 * respect to the given contact.
+	 * the given contact.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -356,8 +339,12 @@ public interface DatabaseComponent {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
-	 * For missing dependencies and dependencies in other groups, the state
+	 * Missing dependencies have the state
-	 * {@link State UNKNOWN} is returned.
+	 * {@link ValidationManager.State UNKNOWN}.
 	 * Dependencies in other groups have the state
 	 * {@link ValidationManager.State INVALID}.
 	 * Note that these states are not set on the dependencies themselves; the
 	 * returned states should only be taken in the context of the given message.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -365,9 +352,9 @@ public interface DatabaseComponent {
 			throws DbException;
 	/**
-	 * Returns the IDs and states of all dependents of the given message.
+	 * Returns all IDs of messages that depend on the given message.
-	 * Dependents in other groups are not returned. If the given message is
+	 * Messages in other groups that declare a dependency on the given message
-	 * missing, no dependents are returned.
+	 * will be returned even though such dependencies are invalid.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -382,8 +369,8 @@ public interface DatabaseComponent {
 	State getMessageState(Transaction txn, MessageId m) throws DbException;
 	/**
-	 * Returns the status of the given delivered message with respect to the
+	 * Returns the status of the given message with respect to the given
-	 * given contact.
+	 * contact.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -412,14 +399,15 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<KeySet> getTransportKeys(Transaction txn, TransportId t)
+	Map<ContactId, TransportKeys> getTransportKeys(Transaction txn,
-			throws DbException;
+			TransportId t) throws DbException;
 	/**
-	 * Increments the outgoing stream counter for the given transport keys.
+	 * Increments the outgoing stream counter for the given contact and
 	 * transport in the given rotation period .
 	 */
-	void incrementStreamCounter(Transaction txn, TransportId t, KeySetId k)
+	void incrementStreamCounter(Transaction txn, ContactId c, TransportId t,
-			throws DbException;
+			long rotationPeriod) throws DbException;
 	/**
 	 * Merges the given metadata with the existing metadata for the given
@@ -489,12 +477,6 @@ public interface DatabaseComponent {
 	 */
 	void removeTransport(Transaction txn, TransportId t) throws DbException;
 	/**
 	 * Removes the given transport keys from the database.
 	 */
 	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
 		throws DbException;
 	/**
 	 * Marks the given contact as verified.
 	 */
@@ -530,21 +512,15 @@ public interface DatabaseComponent {
 			Collection<MessageId> dependencies) throws DbException;
 	/**
-	 * Sets the reordering window for the given key set and transport in the
+	 * Sets the reordering window for the given contact and transport in the
 	 * given rotation period.
 	 */
-	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
+	void setReorderingWindow(Transaction txn, ContactId c, TransportId t,
 			long rotationPeriod, long base, byte[] bitmap) throws DbException;
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
 	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
 		throws DbException;
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
-	void updateTransportKeys(Transaction txn, Collection<KeySet> keys)
+	void updateTransportKeys(Transaction txn,
-			throws DbException;
+			Map<ContactId, TransportKeys> keys) throws DbException;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/event/KeyAgreementStoppedListeningEvent.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/event/KeyAgreementStoppedListeningEvent.java
@@ -1,9 +0,0 @@
 package org.briarproject.bramble.api.keyagreement.event;
 import org.briarproject.bramble.api.event.Event;
 /**
 * An event that is broadcast when a BQP task stops listening.
 */
 public class KeyAgreementStoppedListeningEvent extends Event {
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java
@@ -43,20 +43,17 @@ public interface LifecycleManager {
 	}
 	/**
-	 * Registers a {@link Service} to be started and stopped. This method
+	 * Registers a {@link Service} to be started and stopped.
 	 * should be called before {@link #startServices(String)}.
 	 */
 	void registerService(Service s);
 	/**
-	 * Registers a {@link Client} to be started. This method should be called
+	 * Registers a {@link Client} to be started.
 	 * before {@link #startServices(String)}.
 	 */
 	void registerClient(Client c);
 	/**
-	 * Registers an {@link ExecutorService} to be shut down. This method
+	 * Registers an {@link ExecutorService} to be shut down.
 	 * should be called before {@link #startServices(String)}.
 	 */
 	void registerForShutdown(ExecutorService e);
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TransportId.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TransportId.java
@@ -1,23 +1,22 @@
 package org.briarproject.bramble.api.plugin;
-import org.briarproject.bramble.util.StringUtils;
+import java.nio.charset.Charset;
 /**
- * Type-safe wrapper for a namespaced string that uniquely identifies a
+ * Type-safe wrapper for a string that uniquely identifies a transport plugin.
 * transport plugin.
 */
 public class TransportId {
 	/**
-	 * The maximum length of a transport identifier in UTF-8 bytes.
+	 * The maximum length of transport identifier in UTF-8 bytes.
 	 */
-	public static int MAX_TRANSPORT_ID_LENGTH = 100;
+	public static int MAX_TRANSPORT_ID_LENGTH = 64;
 	private final String id;
 	public TransportId(String id) {
-		int length = StringUtils.toUtf8(id).length;
+		byte[] b = id.getBytes(Charset.forName("UTF-8"));
-		if (length == 0 || length > MAX_TRANSPORT_ID_LENGTH)
+		if (b.length == 0 || b.length > MAX_TRANSPORT_ID_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;
 	}
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java
@@ -15,17 +15,12 @@ public interface TransportPropertyManager {
 	/**
 	 * The unique ID of the transport property client.
 	 */
-	ClientId CLIENT_ID = new ClientId("org.briarproject.bramble.properties");
+	ClientId CLIENT_ID = new ClientId("org.briarproject.briar.properties");
 	/**
-	 * The current major version of the transport property client.
+	 * The current version of the transport property client.
 	 */
-	int MAJOR_VERSION = 0;
+	int CLIENT_VERSION = 0;
 	/**
 	 * The current minor version of the transport property client.
 	 */
 	int MINOR_VERSION = 0;
 	/**
 	 * Stores the given properties received while adding a contact - they will
@@ -42,8 +37,8 @@ public interface TransportPropertyManager {
 	/**
 	 * Returns the local transport properties for all transports.
-	 * <p/>
+	 * <br/>
-	 * Read-only.
+	 * TODO: Transaction can be read-only when code is simplified
 	 */
 	Map<TransportId, TransportProperties> getLocalProperties(Transaction txn)
 			throws DbException;
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/record/Record.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/record/Record.java
@@ -1,36 +0,0 @@
 package org.briarproject.bramble.api.record;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
@Immutable
@NotNullByDefault
 public class Record {
 	public static final int RECORD_HEADER_BYTES = 4;
 	public static final int MAX_RECORD_PAYLOAD_BYTES = 48 * 1024; // 48 KiB
 	private final byte protocolVersion, recordType;
 	private final byte[] payload;
 	public Record(byte protocolVersion, byte recordType, byte[] payload) {
 		if (payload.length > MAX_RECORD_PAYLOAD_BYTES)
 			throw new IllegalArgumentException();
 		this.protocolVersion = protocolVersion;
 		this.recordType = recordType;
 		this.payload = payload;
 	}
 	public byte getProtocolVersion() {
 		return protocolVersion;
 	}
 	public byte getRecordType() {
 		return recordType;
 	}
 	public byte[] getPayload() {
 		return payload;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReader.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReader.java
@@ -1,20 +0,0 @@
 package org.briarproject.bramble.api.record;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.EOFException;
 import java.io.IOException;
@NotNullByDefault
 public interface RecordReader {
 	/**
 	 * Reads and returns the next record.
 	 *
 	 * @throws EOFException if the end of the stream is reached without reading
 	 * a complete record
 	 */
 	Record readRecord() throws IOException;
 	void close() throws IOException;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReaderFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReaderFactory.java
@@ -1,8 +0,0 @@
 package org.briarproject.bramble.api.record;
 import java.io.InputStream;
 public interface RecordReaderFactory {
 	RecordReader createRecordReader(InputStream in);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriter.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriter.java
@@ -1,15 +0,0 @@
 package org.briarproject.bramble.api.record;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.IOException;
@NotNullByDefault
 public interface RecordWriter {
 	void writeRecord(Record r) throws IOException;
 	void flush() throws IOException;
 	void close() throws IOException;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriterFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriterFactory.java
@@ -1,8 +0,0 @@
 package org.briarproject.bramble.api.record;
 import java.io.OutputStream;
 public interface RecordWriterFactory {
 	RecordWriter createRecordWriter(OutputStream out);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/ClientId.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/ClientId.java
@@ -1,29 +1,19 @@
 package org.briarproject.bramble.api.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.util.StringUtils;
 import javax.annotation.concurrent.Immutable;
 /**
- * Type-safe wrapper for a namespaced string that uniquely identifies a sync
+ * Wrapper for a name-spaced string that uniquely identifies a sync client.
 * client.
 */
@Immutable
@NotNullByDefault
 public class ClientId implements Comparable<ClientId> {
 	/**
 	 * The maximum length of a client identifier in UTF-8 bytes.
 	 */
 	public static int MAX_CLIENT_ID_LENGTH = 100;
 	private final String id;
 	public ClientId(String id) {
 		int length = StringUtils.toUtf8(id).length;
 		if (length == 0 || length > MAX_CLIENT_ID_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;
 	}
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/Group.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/Group.java
@@ -5,43 +5,20 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPT
 public class Group {
 	public enum Visibility {
-
+		INVISIBLE, // The group is not visible
-		INVISIBLE(0), // The group is not visible
+		VISIBLE, // The group is visible but messages are not shared
-		VISIBLE(1), // The group is visible, messages are accepted but not sent
+		SHARED // The group is visible and messages are shared
 		SHARED(2); // The group is visible, messages are accepted and sent
 		private final int value;
 		Visibility(int value) {
 			this.value = value;
 		}
 		public int getValue() {
 			return value;
 		}
 		public static Visibility min(Visibility a, Visibility b) {
 			return a.getValue() < b.getValue() ? a : b;
 		}
 	}
 	/**
 	 * The current version of the group format.
 	 */
 	public static final int FORMAT_VERSION = 1;
 	private final GroupId id;
 	private final ClientId clientId;
 	private final int majorVersion;
 	private final byte[] descriptor;
-	public Group(GroupId id, ClientId clientId, int majorVersion,
+	public Group(GroupId id, ClientId clientId, byte[] descriptor) {
 			byte[] descriptor) {
 		if (descriptor.length > MAX_GROUP_DESCRIPTOR_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;
 		this.clientId = clientId;
 		this.majorVersion = majorVersion;
 		this.descriptor = descriptor;
 	}
@@ -59,13 +36,6 @@ public class Group {
 		return clientId;
 	}
 	/**
 	 * Returns the major version of the client to which the group belongs.
 	 */
 	public int getMajorVersion() {
 		return majorVersion;
 	}
 	/**
 	 * Returns the group's descriptor.
 	 */
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/GroupFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/GroupFactory.java
@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 public interface GroupFactory {
 	/**
-	 * Creates a group with the given client ID, major version and descriptor.
+	 * Creates a group with the given client ID, client version and descriptor.
 	 */
-	Group createGroup(ClientId c, int majorVersion, byte[] descriptor);
+	Group createGroup(ClientId c, int clientVersion, byte[] descriptor);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/Message.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/Message.java
@@ -5,11 +5,6 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LEN
 public class Message {
 	/**
 	 * The current version of the message format.
 	 */
 	public static final int FORMAT_VERSION = 1;
 	private final MessageId id;
 	private final GroupId groupId;
 	private final long timestamp;
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageFactory.java
@@ -7,7 +7,5 @@ public interface MessageFactory {
 	Message createMessage(GroupId g, long timestamp, byte[] body);
 	Message createMessage(byte[] raw);
 	Message createMessage(MessageId m, byte[] raw);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageId.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageId.java
@@ -16,13 +16,7 @@ public class MessageId extends UniqueId {
 	/**
 	 * Label for hashing messages to calculate their identifiers.
 	 */
-	public static final String ID_LABEL = "org.briarproject.bramble/MESSAGE_ID";
+	public static final String LABEL = "org.briarproject.bramble/MESSAGE_ID";
 	/**
 	 * Label for hashing blocks of messages.
 	 */
 	public static final String BLOCK_LABEL =
 			"org.briarproject.bramble/MESSAGE_BLOCK";
 	public MessageId(byte[] id) {
 		super(id);
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordReader.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordReader.java
@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.IOException;
@NotNullByDefault
-public interface SyncRecordReader {
+public interface RecordReader {
 	boolean eof() throws IOException;
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordReaderFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordReaderFactory.java
@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.InputStream;
@NotNullByDefault
-public interface SyncRecordReaderFactory {
+public interface RecordReaderFactory {
-	SyncRecordReader createRecordReader(InputStream in);
+	RecordReader createRecordReader(InputStream in);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriter.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriter.java
@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.IOException;
@NotNullByDefault
-public interface SyncRecordWriter {
+public interface RecordWriter {
 	void writeAck(Ack a) throws IOException;
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriterFactory.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriterFactory.java
@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.OutputStream;
@NotNullByDefault
-public interface SyncRecordWriterFactory {
+public interface RecordWriterFactory {
-	SyncRecordWriter createRecordWriter(OutputStream out);
+	RecordWriter createRecordWriter(OutputStream out);
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncConstants.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncConstants.java
@@ -2,8 +2,6 @@ package org.briarproject.bramble.api.sync;
 import org.briarproject.bramble.api.UniqueId;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 public interface SyncConstants {
 	/**
@@ -12,8 +10,16 @@ public interface SyncConstants {
 	byte PROTOCOL_VERSION = 0;
 	/**
-	 * The maximum length of a group descriptor in bytes.
+	 * The length of the record header in bytes.
 	 */
 	int RECORD_HEADER_LENGTH = 4;
 	/**
 	 * The maximum length of the record payload in bytes.
 	 */
 	int MAX_RECORD_PAYLOAD_LENGTH = 48 * 1024; // 48 KiB
 	/** The maximum length of a group descriptor in bytes. */
 	int MAX_GROUP_DESCRIPTOR_LENGTH = 16 * 1024; // 16 KiB
 	/**
@@ -34,5 +40,5 @@ public interface SyncConstants {
 	/**
 	 * The maximum number of message IDs in an ack, offer or request record.
 	 */
-	int MAX_MESSAGE_IDS = MAX_RECORD_PAYLOAD_BYTES / UniqueId.LENGTH;
+	int MAX_MESSAGE_IDS = MAX_RECORD_PAYLOAD_LENGTH / UniqueId.LENGTH;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/sync/ValidationManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/sync/ValidationManager.java
@@ -3,7 +3,6 @@ package org.briarproject.bramble.api.sync;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 /**
@@ -34,20 +33,15 @@ public interface ValidationManager {
 	}
 	/**
-	 * Registers the message validator for the given client. This method
+	 * Sets the message validator for the given client.
 	 * should be called before {@link LifecycleManager#startServices(String)}.
 	 */
-	void registerMessageValidator(ClientId c, int majorVersion,
+	void registerMessageValidator(ClientId c, MessageValidator v);
 			MessageValidator v);
 	/**
-	 * Registers the incoming message hook for the given client. The hook will
+	 * Sets the incoming message hook for the given client. The hook will be
-	 * be called once for each incoming message that passes validation. This
+	 * called once for each incoming message that passes validation.
 	 * method should be called before
 	 * {@link LifecycleManager#startServices(String)}.
 	 */
-	void registerIncomingMessageHook(ClientId c, int majorVersion,
+	void registerIncomingMessageHook(ClientId c, IncomingMessageHook hook);
 			IncomingMessageHook hook);
 	interface MessageValidator {
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/system/Clock.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/system/Clock.java
@@ -7,12 +7,12 @@ package org.briarproject.bramble.api.system;
 public interface Clock {
 	/**
-	 * @see System#currentTimeMillis()
+	 * @see {@link System#currentTimeMillis()}
 	 */
 	long currentTimeMillis();
 	/**
-	 * @see Thread#sleep(long)
+	 * @see {@link Thread#sleep(long)}
 	 */
 	void sleep(long milliseconds) throws InterruptedException;
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeyManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeyManager.java
@@ -6,8 +6,6 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.plugin.TransportId;
 import java.util.Map;
 import javax.annotation.Nullable;
 /**
@@ -18,55 +16,13 @@ public interface KeyManager {
 	/**
 	 * Informs the key manager that a new contact has been added. Derives and
-	 * stores a set of transport keys for communicating with the contact over
+	 * stores transport keys for communicating with the contact.
 	 * each transport.
 	 * <p/>
 	 * {@link StreamContext StreamContexts} for the contact can be created
 	 * after this method has returned.
 	 *
 	 * @param alice true if the local party is Alice
 	 */
 	void addContact(Transaction txn, ContactId c, SecretKey master,
 			long timestamp, boolean alice) throws DbException;
 	/**
 	 * Derives and stores a set of unbound transport keys for each transport
 	 * and returns the key set IDs.
 	 * <p/>
 	 * The keys must be bound before they can be used for incoming streams,
 	 * and also activated before they can be used for outgoing streams.
 	 *
 	 * @param alice true if the local party is Alice
 	 */
 	Map<TransportId, KeySetId> addUnboundKeys(Transaction txn, SecretKey master,
 			long timestamp, boolean alice) throws DbException;
 	/**
 	 * Binds the given transport keys to the given contact.
 	 */
 	void bindKeys(Transaction txn, ContactId c, Map<TransportId, KeySetId> keys)
 			throws DbException;
 	/**
 	 * Marks the given transport keys as usable for outgoing streams. Keys must
 	 * be bound before they are activated.
 	 */
 	void activateKeys(Transaction txn, Map<TransportId, KeySetId> keys)
 			throws DbException;
 	/**
 	 * Removes the given transport keys, which must not have been bound, from
 	 * the manager and the database.
 	 */
 	void removeKeys(Transaction txn, Map<TransportId, KeySetId> keys)
 			throws DbException;
 	/**
 	 * Returns true if we have keys that can be used for outgoing streams to
 	 * the given contact over the given transport.
 	 */
 	boolean canSendOutgoingStreams(ContactId c, TransportId t);
 	/**
 	 * Returns a {@link StreamContext} for sending a stream to the given
 	 * contact over the given transport, or null if an error occurs or the
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySet.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySet.java
@@ -1,51 +0,0 @@
 package org.briarproject.bramble.api.transport;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 /**
 * A set of transport keys for communicating with a contact. If the keys have
 * not yet been bound to a contact, {@link #getContactId()}} returns null.
 */
@Immutable
@NotNullByDefault
 public class KeySet {
 	private final KeySetId keySetId;
 	@Nullable
 	private final ContactId contactId;
 	private final TransportKeys transportKeys;
 	public KeySet(KeySetId keySetId, @Nullable ContactId contactId,
 			TransportKeys transportKeys) {
 		this.keySetId = keySetId;
 		this.contactId = contactId;
 		this.transportKeys = transportKeys;
 	}
 	public KeySetId getKeySetId() {
 		return keySetId;
 	}
 	@Nullable
 	public ContactId getContactId() {
 		return contactId;
 	}
 	public TransportKeys getTransportKeys() {
 		return transportKeys;
 	}
 	@Override
 	public int hashCode() {
 		return keySetId.hashCode();
 	}
 	@Override
 	public boolean equals(Object o) {
 		return o instanceof KeySet && keySetId.equals(((KeySet) o).keySetId);
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySetId.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySetId.java
@@ -1,36 +0,0 @@
 package org.briarproject.bramble.api.transport;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 /**
 * Type-safe wrapper for an integer that uniquely identifies a set of transport
 * keys within the scope of the local device.
 * <p/>
 * Key sets created on a given device must have increasing identifiers.
 */
@Immutable
@NotNullByDefault
 public class KeySetId {
 	private final int id;
 	public KeySetId(int id) {
 		this.id = id;
 	}
 	public int getInt() {
 		return id;
 	}
 	@Override
 	public int hashCode() {
 		return id;
 	}
 	@Override
 	public boolean equals(Object o) {
 		return o instanceof KeySetId && id == ((KeySetId) o).id;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/transport/OutgoingKeys.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/transport/OutgoingKeys.java
@@ -10,20 +10,18 @@ public class OutgoingKeys {
 	private final SecretKey tagKey, headerKey;
 	private final long rotationPeriod, streamCounter;
 	private final boolean active;
 	public OutgoingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod, boolean active) {
+			long rotationPeriod) {
-		this(tagKey, headerKey, rotationPeriod, 0, active);
+		this(tagKey, headerKey, rotationPeriod, 0);
 	}
 	public OutgoingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod, long streamCounter, boolean active) {
+			long rotationPeriod, long streamCounter) {
 		this.tagKey = tagKey;
 		this.headerKey = headerKey;
 		this.rotationPeriod = rotationPeriod;
 		this.streamCounter = streamCounter;
 		this.active = active;
 	}
 	public SecretKey getTagKey() {
@@ -41,8 +39,4 @@ public class OutgoingKeys {
 	public long getStreamCounter() {
 		return streamCounter;
 	}
 	public boolean isActive() {
 		return active;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/versioning/ClientMajorVersion.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/versioning/ClientMajorVersion.java
@@ -1,50 +0,0 @@
 package org.briarproject.bramble.api.versioning;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.ClientId;
 import javax.annotation.concurrent.Immutable;
@Immutable
@NotNullByDefault
 public class ClientMajorVersion implements Comparable<ClientMajorVersion> {
 	private final ClientId clientId;
 	private final int majorVersion;
 	public ClientMajorVersion(ClientId clientId, int majorVersion) {
 		this.clientId = clientId;
 		this.majorVersion = majorVersion;
 	}
 	public ClientId getClientId() {
 		return clientId;
 	}
 	public int getMajorVersion() {
 		return majorVersion;
 	}
 	@Override
 	public boolean equals(Object o) {
 		if (o instanceof ClientMajorVersion) {
 			ClientMajorVersion cv = (ClientMajorVersion) o;
 			return clientId.equals(cv.clientId)
 					&& majorVersion == cv.majorVersion;
 		}
 		return false;
 	}
 	@Override
 	public int hashCode() {
 		return (clientId.hashCode() << 16) + majorVersion;
 	}
 	@Override
 	public int compareTo(ClientMajorVersion cv) {
 		int compare = clientId.compareTo(cv.clientId);
 		if (compare != 0) return compare;
 		return majorVersion - cv.majorVersion;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/versioning/ClientVersioningManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/versioning/ClientVersioningManager.java
@@ -1,45 +0,0 @@
 package org.briarproject.bramble.api.versioning;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.ClientId;
 import org.briarproject.bramble.api.sync.Group.Visibility;
@NotNullByDefault
 public interface ClientVersioningManager {
 	/**
 	 * The unique ID of the versioning client.
 	 */
 	ClientId CLIENT_ID = new ClientId("org.briarproject.bramble.versioning");
 	/**
 	 * The current major version of the versioning client.
 	 */
 	int MAJOR_VERSION = 0;
 	/**
 	 * Registers a client that will be advertised to contacts. The hook will
 	 * be called when the visibility of the client changes. This method should
 	 * be called before {@link LifecycleManager#startServices(String)}.
 	 */
 	void registerClient(ClientId clientId, int majorVersion, int minorVersion,
 			ClientVersioningHook hook);
 	/**
 	 * Returns the visibility of the given client with respect to the given
 	 * contact.
 	 */
 	Visibility getClientVisibility(Transaction txn, ContactId contactId,
 			ClientId clientId, int majorVersion) throws DbException;
 	interface ClientVersioningHook {
 		void onClientVisibilityChanging(Transaction txn, Contact c,
 				Visibility v) throws DbException;
 	}
 }
--- a/bramble-api/src/main/java/org/briarproject/bramble/util/StringUtils.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/util/StringUtils.java
@@ -146,6 +146,14 @@ public class StringUtils {
 		return s.toString();
 	}
 	public static String ipToString(int ip) {
 		int ip1 = ip & 0xFF;
 		int ip2 = (ip >> 8) & 0xFF;
 		int ip3 = (ip >> 16) & 0xFF;
 		int ip4 = (ip >> 24) & 0xFF;
 		return ip1 + "." + ip2 + "." + ip3 + "." + ip4;
 	}
 	public static String getRandomString(int length) {
 		char[] c = new char[length];
 		for (int i = 0; i < length; i++)
--- a/bramble-api/src/test/java/org/briarproject/bramble/test/TestUtils.java
+++ b/bramble-api/src/test/java/org/briarproject/bramble/test/TestUtils.java
@@ -5,8 +5,6 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.ClientId;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.GroupId;
@@ -18,18 +16,13 @@ import java.io.File;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.plugin.TransportId.MAX_TRANSPORT_ID_LENGTH;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTY_LENGTH;
 import static org.briarproject.bramble.api.sync.ClientId.MAX_CLIENT_ID_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
@@ -61,33 +54,6 @@ public class TestUtils {
 		return getRandomBytes(UniqueId.LENGTH);
 	}
 	public static ClientId getClientId() {
 		return new ClientId(getRandomString(MAX_CLIENT_ID_LENGTH));
 	}
 	public static TransportId getTransportId() {
 		return new TransportId(getRandomString(MAX_TRANSPORT_ID_LENGTH));
 	}
 	public static TransportProperties getTransportProperties(int number) {
 		TransportProperties tp = new TransportProperties();
 		for (int i = 0; i < number; i++) {
 			tp.put(getRandomString(1 + random.nextInt(MAX_PROPERTY_LENGTH)),
 					getRandomString(1 + random.nextInt(MAX_PROPERTY_LENGTH))
 			);
 		}
 		return tp;
 	}
 	public static Map<TransportId, TransportProperties> getTransportPropertiesMap(
 			int number) {
 		Map<TransportId, TransportProperties> map = new HashMap<>();
 		for (int i = 0; i < number; i++) {
 			map.put(getTransportId(), getTransportProperties(number));
 		}
 		return map;
 	}
 	public static SecretKey getSecretKey() {
 		return new SecretKey(getRandomBytes(SecretKey.LENGTH));
 	}
@@ -117,16 +83,15 @@ public class TestUtils {
 		return new Author(id, FORMAT_VERSION, name, publicKey);
 	}
-	public static Group getGroup(ClientId clientId, int majorVersion) {
+	public static Group getGroup(ClientId clientId) {
 		int descriptorLength = 1 + random.nextInt(MAX_GROUP_DESCRIPTOR_LENGTH);
-		return getGroup(clientId, majorVersion, descriptorLength);
+		return getGroup(clientId, descriptorLength);
 	}
-	public static Group getGroup(ClientId clientId, int majorVersion,
+	public static Group getGroup(ClientId clientId, int descriptorLength) {
 			int descriptorLength) {
 		GroupId groupId = new GroupId(getRandomId());
 		byte[] descriptor = getRandomBytes(descriptorLength);
-		return new Group(groupId, clientId, majorVersion, descriptor);
+		return new Group(groupId, clientId, descriptor);
 	}
 	public static Message getMessage(GroupId groupId) {
--- a/bramble-core/build.gradle
+++ b/bramble-core/build.gradle
@@ -31,6 +31,7 @@ dependencies {
 dependencyVerification {
 	verify = [
 			'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
 			'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
 			'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
 			'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
 			'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
--- a/bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreEagerSingletons.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreEagerSingletons.java
@@ -1,7 +1,7 @@
 package org.briarproject.bramble;
 import org.briarproject.bramble.contact.ContactModule;
-import org.briarproject.bramble.crypto.CryptoExecutorModule;
+import org.briarproject.bramble.crypto.CryptoModule;
 import org.briarproject.bramble.db.DatabaseExecutorModule;
 import org.briarproject.bramble.identity.IdentityModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
@@ -10,13 +10,12 @@ import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 public interface BrambleCoreEagerSingletons {
 	void inject(ContactModule.EagerSingletons init);
-	void inject(CryptoExecutorModule.EagerSingletons init);
+	void inject(CryptoModule.EagerSingletons init);
 	void inject(DatabaseExecutorModule.EagerSingletons init);
@@ -33,6 +32,4 @@ public interface BrambleCoreEagerSingletons {
 	void inject(SystemModule.EagerSingletons init);
 	void inject(TransportModule.EagerSingletons init);
 	void inject(VersioningModule.EagerSingletons init);
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java
@@ -2,7 +2,6 @@ package org.briarproject.bramble;
 import org.briarproject.bramble.client.ClientModule;
 import org.briarproject.bramble.contact.ContactModule;
 import org.briarproject.bramble.crypto.CryptoExecutorModule;
 import org.briarproject.bramble.crypto.CryptoModule;
 import org.briarproject.bramble.data.DataModule;
 import org.briarproject.bramble.db.DatabaseExecutorModule;
@@ -13,7 +12,6 @@ import org.briarproject.bramble.keyagreement.KeyAgreementModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.record.RecordModule;
 import org.briarproject.bramble.reliability.ReliabilityModule;
 import org.briarproject.bramble.reporting.ReportingModule;
 import org.briarproject.bramble.settings.SettingsModule;
@@ -21,7 +19,6 @@ import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 import dagger.Module;
@@ -29,7 +26,6 @@ import dagger.Module;
 		ClientModule.class,
 		ContactModule.class,
 		CryptoModule.class,
 		CryptoExecutorModule.class,
 		DataModule.class,
 		DatabaseModule.class,
 		DatabaseExecutorModule.class,
@@ -39,21 +35,19 @@ import dagger.Module;
 		LifecycleModule.class,
 		PluginModule.class,
 		PropertiesModule.class,
 		RecordModule.class,
 		ReliabilityModule.class,
 		ReportingModule.class,
 		SettingsModule.class,
 		SocksModule.class,
 		SyncModule.class,
 		SystemModule.class,
-		TransportModule.class,
+		TransportModule.class
 		VersioningModule.class
 })
 public class BrambleCoreModule {
 	public static void initEagerSingletons(BrambleCoreEagerSingletons c) {
 		c.inject(new ContactModule.EagerSingletons());
-		c.inject(new CryptoExecutorModule.EagerSingletons());
+		c.inject(new CryptoModule.EagerSingletons());
 		c.inject(new DatabaseExecutorModule.EagerSingletons());
 		c.inject(new IdentityModule.EagerSingletons());
 		c.inject(new LifecycleModule.EagerSingletons());
@@ -62,6 +56,5 @@ public class BrambleCoreModule {
 		c.inject(new SyncModule.EagerSingletons());
 		c.inject(new SystemModule.EagerSingletons());
 		c.inject(new TransportModule.EagerSingletons());
 		c.inject(new VersioningModule.EagerSingletons());
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java
@@ -18,8 +18,6 @@ import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
@@ -39,8 +37,6 @@ import javax.inject.Inject;
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTIES_PER_TRANSPORT;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
@@ -328,20 +324,6 @@ class ClientHelperImpl implements ClientHelper {
 		}
 	}
 	@Override
 	public BdfDictionary toDictionary(TransportProperties transportProperties) {
 		return new BdfDictionary(transportProperties);
 	}
 	@Override
 	public BdfDictionary toDictionary(
 			Map<TransportId, TransportProperties> map) {
 		BdfDictionary d = new BdfDictionary();
 		for (Entry<TransportId, TransportProperties> e : map.entrySet())
 			d.put(e.getKey().getString(), new BdfDictionary(e.getValue()));
 		return d;
 	}
 	@Override
 	public BdfList toList(byte[] b, int off, int len) throws FormatException {
 		ByteArrayInputStream in = new ByteArrayInputStream(b, off, len);
@@ -381,10 +363,9 @@ class ClientHelperImpl implements ClientHelper {
 	}
 	@Override
-	public void verifySignature(byte[] signature, String label, BdfList signed,
+	public void verifySignature(String label, byte[] sig, byte[] publicKey,
-			byte[] publicKey) throws FormatException, GeneralSecurityException {
+			BdfList signed) throws FormatException, GeneralSecurityException {
-		if (!crypto.verifySignature(signature, label, toByteArray(signed),
+		if (!crypto.verify(label, toByteArray(signed), publicKey, sig)) {
 				publicKey)) {
 			throw new GeneralSecurityException("Invalid signature");
 		}
 	}
@@ -401,33 +382,4 @@ class ClientHelperImpl implements ClientHelper {
 		checkLength(publicKey, 1, MAX_PUBLIC_KEY_LENGTH);
 		return authorFactory.createAuthor(formatVersion, name, publicKey);
 	}
 	@Override
 	public TransportProperties parseAndValidateTransportProperties(
 			BdfDictionary properties) throws FormatException {
 		checkSize(properties, 0, MAX_PROPERTIES_PER_TRANSPORT);
 		TransportProperties p = new TransportProperties();
 		for (String key : properties.keySet()) {
 			checkLength(key, 1, MAX_PROPERTY_LENGTH);
 			String value = properties.getString(key);
 			checkLength(value, 1, MAX_PROPERTY_LENGTH);
 			p.put(key, value);
 		}
 		return p;
 	}
 	@Override
 	public Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException {
 		Map<TransportId, TransportProperties> tpMap = new HashMap<>();
 		for (String key : properties.keySet()) {
 			TransportId transportId = new TransportId(key);
 			TransportProperties transportProperties =
 					parseAndValidateTransportProperties(
 							properties.getDictionary(key));
 			tpMap.put(transportId, transportProperties);
 		}
 		return tpMap;
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/client/ContactGroupFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/client/ContactGroupFactoryImpl.java
@@ -32,25 +32,25 @@ class ContactGroupFactoryImpl implements ContactGroupFactory {
 	}
 	@Override
-	public Group createLocalGroup(ClientId clientId, int majorVersion) {
+	public Group createLocalGroup(ClientId clientId, int clientVersion) {
-		return groupFactory.createGroup(clientId, majorVersion,
+		return groupFactory.createGroup(clientId, clientVersion,
 				LOCAL_GROUP_DESCRIPTOR);
 	}
 	@Override
-	public Group createContactGroup(ClientId clientId, int majorVersion,
+	public Group createContactGroup(ClientId clientId, int clientVersion,
 			Contact contact) {
 		AuthorId local = contact.getLocalAuthorId();
 		AuthorId remote = contact.getAuthor().getId();
 		byte[] descriptor = createGroupDescriptor(local, remote);
-		return groupFactory.createGroup(clientId, majorVersion, descriptor);
+		return groupFactory.createGroup(clientId, clientVersion, descriptor);
 	}
 	@Override
-	public Group createContactGroup(ClientId clientId, int majorVersion,
+	public Group createContactGroup(ClientId clientId, int clientVersion,
 			AuthorId authorId1, AuthorId authorId2) {
 		byte[] descriptor = createGroupDescriptor(authorId1, authorId2);
-		return groupFactory.createGroup(clientId, majorVersion, descriptor);
+		return groupFactory.createGroup(clientId, clientVersion, descriptor);
 	}
 	private byte[] createGroupDescriptor(AuthorId local, AuthorId remote) {
--- a/bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeTaskImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeTaskImpl.java
@@ -1,20 +1,23 @@
 package org.briarproject.bramble.contact;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.contact.ContactExchangeListener;
 import org.briarproject.bramble.api.contact.ContactExchangeTask;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
 import org.briarproject.bramble.api.data.BdfWriter;
 import org.briarproject.bramble.api.data.BdfWriterFactory;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -23,30 +26,30 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.record.Record;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.StreamReaderFactory;
 import org.briarproject.bramble.api.transport.StreamWriterFactory;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.security.GeneralSecurityException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.logging.Logger;
 import javax.inject.Inject;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.api.contact.RecordTypes.CONTACT_INFO;
+import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
-import static org.briarproject.bramble.util.ValidationUtils.checkLength;
+import static org.briarproject.bramble.api.plugin.TransportId.MAX_TRANSPORT_ID_LENGTH;
-import static org.briarproject.bramble.util.ValidationUtils.checkSize;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTIES_PER_TRANSPORT;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTY_LENGTH;
@MethodsNotNullByDefault
@ParametersNotNullByDefault
@@ -59,9 +62,9 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			"org.briarproject.briar.contact/EXCHANGE";
 	private final DatabaseComponent db;
-	private final ClientHelper clientHelper;
+	private final AuthorFactory authorFactory;
-	private final RecordReaderFactory recordReaderFactory;
+	private final BdfReaderFactory bdfReaderFactory;
-	private final RecordWriterFactory recordWriterFactory;
+	private final BdfWriterFactory bdfWriterFactory;
 	private final Clock clock;
 	private final ConnectionManager connectionManager;
 	private final ContactManager contactManager;
@@ -78,17 +81,17 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private volatile boolean alice;
 	@Inject
-	ContactExchangeTaskImpl(DatabaseComponent db, ClientHelper clientHelper,
+	ContactExchangeTaskImpl(DatabaseComponent db,
-			RecordReaderFactory recordReaderFactory,
+			AuthorFactory authorFactory, BdfReaderFactory bdfReaderFactory,
-			RecordWriterFactory recordWriterFactory, Clock clock,
+			BdfWriterFactory bdfWriterFactory, Clock clock,
 			ConnectionManager connectionManager, ContactManager contactManager,
 			TransportPropertyManager transportPropertyManager,
 			CryptoComponent crypto, StreamReaderFactory streamReaderFactory,
 			StreamWriterFactory streamWriterFactory) {
 		this.db = db;
-		this.clientHelper = clientHelper;
+		this.authorFactory = authorFactory;
-		this.recordReaderFactory = recordReaderFactory;
+		this.bdfReaderFactory = bdfReaderFactory;
-		this.recordWriterFactory = recordWriterFactory;
+		this.bdfWriterFactory = bdfWriterFactory;
 		this.clock = clock;
 		this.connectionManager = connectionManager;
 		this.contactManager = contactManager;
@@ -123,18 +126,18 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			listener.contactExchangeFailed();
-			tryToClose(conn);
+			tryToClose(conn, true);
 			return;
 		}
 		// Get the local transport properties
-		Map<TransportId, TransportProperties> localProperties;
+		Map<TransportId, TransportProperties> localProperties, remoteProperties;
 		try {
 			localProperties = transportPropertyManager.getLocalProperties();
 		} catch (DbException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			listener.contactExchangeFailed();
-			tryToClose(conn);
+			tryToClose(conn, true);
 			return;
 		}
@@ -148,138 +151,158 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		InputStream streamReader =
 				streamReaderFactory.createContactExchangeStreamReader(in,
 						alice ? bobHeaderKey : aliceHeaderKey);
-		RecordReader recordReader =
+		BdfReader r = bdfReaderFactory.createReader(streamReader);
 				recordReaderFactory.createRecordReader(streamReader);
 		// Create the writers
 		OutputStream streamWriter =
 				streamWriterFactory.createContactExchangeStreamWriter(out,
 						alice ? aliceHeaderKey : bobHeaderKey);
-		RecordWriter recordWriter =
+		BdfWriter w = bdfWriterFactory.createWriter(streamWriter);
 				recordWriterFactory.createRecordWriter(streamWriter);
 		// Derive the nonces to be signed
 		byte[] aliceNonce = crypto.mac(ALICE_NONCE_LABEL, masterSecret,
 				new byte[] {PROTOCOL_VERSION});
 		byte[] bobNonce = crypto.mac(BOB_NONCE_LABEL, masterSecret,
 				new byte[] {PROTOCOL_VERSION});
 		byte[] localNonce = alice ? aliceNonce : bobNonce;
 		byte[] remoteNonce = alice ? bobNonce : aliceNonce;
-		// Sign the nonce
+		// Exchange pseudonyms, signed nonces, and timestamps
 		byte[] localSignature = sign(localAuthor, localNonce);
 		// Exchange contact info
 		long localTimestamp = clock.currentTimeMillis();
-		ContactInfo remoteInfo;
+		Author remoteAuthor;
 		long remoteTimestamp;
 		try {
 			if (alice) {
-				sendContactInfo(recordWriter, localAuthor, localProperties,
+				sendPseudonym(w, aliceNonce);
-						localSignature, localTimestamp);
+				sendTimestamp(w, localTimestamp);
-				recordWriter.flush();
+				sendTransportProperties(w, localProperties);
-				remoteInfo = receiveContactInfo(recordReader);
+				w.flush();
 				remoteAuthor = receivePseudonym(r, bobNonce);
 				remoteTimestamp = receiveTimestamp(r);
 				remoteProperties = receiveTransportProperties(r);
 			} else {
-				remoteInfo = receiveContactInfo(recordReader);
+				remoteAuthor = receivePseudonym(r, aliceNonce);
-				sendContactInfo(recordWriter, localAuthor, localProperties,
+				remoteTimestamp = receiveTimestamp(r);
-						localSignature, localTimestamp);
+				remoteProperties = receiveTransportProperties(r);
-				recordWriter.flush();
+				sendPseudonym(w, bobNonce);
 				sendTimestamp(w, localTimestamp);
 				sendTransportProperties(w, localProperties);
 				w.flush();
 			}
-			// Close the outgoing stream
+			// Close the outgoing stream and expect EOF on the incoming stream
-			recordWriter.close();
+			w.close();
-			// Skip any remaining records from the incoming stream
+			if (!r.eof()) LOG.warning("Unexpected data at end of connection");
-			try {
+		} catch (GeneralSecurityException | IOException e) {
 				while (true) recordReader.readRecord();
 			} catch (EOFException expected) {
 				LOG.info("End of stream");
 			}
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			listener.contactExchangeFailed();
-			tryToClose(conn);
+			tryToClose(conn, true);
 			return;
 		}
 		// Verify the contact's signature
 		if (!verify(remoteInfo.author, remoteNonce, remoteInfo.signature)) {
 			LOG.warning("Invalid signature");
 			listener.contactExchangeFailed();
 			tryToClose(conn);
 			return;
 		}
 		// The agreed timestamp is the minimum of the peers' timestamps
-		long timestamp = Math.min(localTimestamp, remoteInfo.timestamp);
+		long timestamp = Math.min(localTimestamp, remoteTimestamp);
 		try {
 			// Add the contact
-			ContactId contactId = addContact(remoteInfo.author, timestamp,
+			ContactId contactId = addContact(remoteAuthor, timestamp,
-					remoteInfo.properties);
+					remoteProperties);
 			// Reuse the connection as a transport connection
 			connectionManager.manageOutgoingConnection(contactId, transportId,
 					conn);
 			// Pseudonym exchange succeeded
 			LOG.info("Pseudonym exchange succeeded");
-			listener.contactExchangeSucceeded(remoteInfo.author);
+			listener.contactExchangeSucceeded(remoteAuthor);
 		} catch (ContactExistsException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			tryToClose(conn);
+			tryToClose(conn, true);
-			listener.duplicateContact(remoteInfo.author);
+			listener.duplicateContact(remoteAuthor);
 		} catch (DbException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			tryToClose(conn);
+			tryToClose(conn, true);
 			listener.contactExchangeFailed();
 		}
 	}
-	private byte[] sign(LocalAuthor author, byte[] nonce) {
+	private void sendPseudonym(BdfWriter w, byte[] nonce)
-		try {
+			throws GeneralSecurityException, IOException {
-			return crypto.sign(SIGNING_LABEL_EXCHANGE, nonce,
+		// Sign the nonce
-					author.getPrivateKey());
+		byte[] privateKey = localAuthor.getPrivateKey();
-		} catch (GeneralSecurityException e) {
+		byte[] sig = crypto.sign(SIGNING_LABEL_EXCHANGE, nonce, privateKey);
-			throw new AssertionError();
+
 		// Write the name, public key and signature
 		w.writeListStart();
 		w.writeLong(localAuthor.getFormatVersion());
 		w.writeString(localAuthor.getName());
 		w.writeRaw(localAuthor.getPublicKey());
 		w.writeRaw(sig);
 		w.writeListEnd();
 		LOG.info("Sent pseudonym");
 	}
 	private Author receivePseudonym(BdfReader r, byte[] nonce)
 			throws GeneralSecurityException, IOException {
 		// Read the format version, name, public key and signature
 		r.readListStart();
 		int formatVersion = (int) r.readLong();
 		if (formatVersion != FORMAT_VERSION) throw new FormatException();
 		String name = r.readString(MAX_AUTHOR_NAME_LENGTH);
 		if (name.isEmpty()) throw new FormatException();
 		byte[] publicKey = r.readRaw(MAX_PUBLIC_KEY_LENGTH);
 		if (publicKey.length == 0) throw new FormatException();
 		byte[] sig = r.readRaw(MAX_SIGNATURE_LENGTH);
 		if (sig.length == 0) throw new FormatException();
 		r.readListEnd();
 		LOG.info("Received pseudonym");
 		// Verify the signature
 		if (!crypto.verify(SIGNING_LABEL_EXCHANGE, nonce, publicKey, sig)) {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Invalid signature");
 			throw new GeneralSecurityException();
 		}
 		return authorFactory.createAuthor(formatVersion, name, publicKey);
 	}
-	private boolean verify(Author author, byte[] nonce, byte[] signature) {
+	private void sendTimestamp(BdfWriter w, long timestamp)
 		try {
 			return crypto.verifySignature(signature, SIGNING_LABEL_EXCHANGE,
 					nonce, author.getPublicKey());
 		} catch (GeneralSecurityException e) {
 			return false;
 		}
 	}
 	private void sendContactInfo(RecordWriter recordWriter, Author author,
 			Map<TransportId, TransportProperties> properties, byte[] signature,
 			long timestamp) throws IOException {
 		BdfList authorList = clientHelper.toList(author);
 		BdfDictionary props = clientHelper.toDictionary(properties);
 		BdfList payload = BdfList.of(authorList, props, signature, timestamp);
 		recordWriter.writeRecord(new Record(PROTOCOL_VERSION, CONTACT_INFO,
 				clientHelper.toByteArray(payload)));
 		LOG.info("Sent contact info");
 	}
 	private ContactInfo receiveContactInfo(RecordReader recordReader)
 			throws IOException {
-		Record record;
+		w.writeLong(timestamp);
-		do {
+		LOG.info("Sent timestamp");
-			record = recordReader.readRecord();
+	}
-			if (record.getProtocolVersion() != PROTOCOL_VERSION)
+
-				throw new FormatException();
+	private long receiveTimestamp(BdfReader r) throws IOException {
-		} while (record.getRecordType() != CONTACT_INFO);
+		long timestamp = r.readLong();
 		LOG.info("Received contact info");
 		BdfList payload = clientHelper.toList(record.getPayload());
 		checkSize(payload, 4);
 		Author author = clientHelper.parseAndValidateAuthor(payload.getList(0));
 		BdfDictionary props = payload.getDictionary(1);
 		Map<TransportId, TransportProperties> properties =
 				clientHelper.parseAndValidateTransportPropertiesMap(props);
 		byte[] signature = payload.getRaw(2);
 		checkLength(signature, 1, MAX_SIGNATURE_LENGTH);
 		long timestamp = payload.getLong(3);
 		if (timestamp < 0) throw new FormatException();
-		return new ContactInfo(author, properties, signature, timestamp);
+		LOG.info("Received timestamp");
 		return timestamp;
 	}
 	private void sendTransportProperties(BdfWriter w,
 			Map<TransportId, TransportProperties> local) throws IOException {
 		w.writeListStart();
 		for (Entry<TransportId, TransportProperties> e : local.entrySet())
 			w.writeList(BdfList.of(e.getKey().getString(), e.getValue()));
 		w.writeListEnd();
 	}
 	private Map<TransportId, TransportProperties> receiveTransportProperties(
 			BdfReader r) throws IOException {
 		Map<TransportId, TransportProperties> remote = new HashMap<>();
 		r.readListStart();
 		while (!r.hasListEnd()) {
 			r.readListStart();
 			String id = r.readString(MAX_TRANSPORT_ID_LENGTH);
 			if (id.isEmpty()) throw new FormatException();
 			TransportProperties p = new TransportProperties();
 			r.readDictionaryStart();
 			while (!r.hasDictionaryEnd()) {
 				if (p.size() == MAX_PROPERTIES_PER_TRANSPORT)
 					throw new FormatException();
 				String key = r.readString(MAX_PROPERTY_LENGTH);
 				String value = r.readString(MAX_PROPERTY_LENGTH);
 				p.put(key, value);
 			}
 			r.readDictionaryEnd();
 			r.readListEnd();
 			remote.put(new TransportId(id), p);
 		}
 		r.readListEnd();
 		return remote;
 	}
 	private ContactId addContact(Author remoteAuthor, long timestamp,
@@ -300,30 +323,13 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		return contactId;
 	}
-	private void tryToClose(DuplexTransportConnection conn) {
+	private void tryToClose(DuplexTransportConnection conn, boolean exception) {
 		try {
 			LOG.info("Closing connection");
-			conn.getReader().dispose(true, true);
+			conn.getReader().dispose(exception, true);
-			conn.getWriter().dispose(true);
+			conn.getWriter().dispose(exception);
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 		}
 	}
 	private static class ContactInfo {
 		private final Author author;
 		private final Map<TransportId, TransportProperties> properties;
 		private final byte[] signature;
 		private final long timestamp;
 		private ContactInfo(Author author,
 				Map<TransportId, TransportProperties> properties,
 				byte[] signature, long timestamp) {
 			this.author = author;
 			this.properties = properties;
 			this.signature = signature;
 			this.timestamp = timestamp;
 		}
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java
@@ -27,37 +27,36 @@ class ContactManagerImpl implements ContactManager {
 	private final DatabaseComponent db;
 	private final KeyManager keyManager;
-	private final List<ContactHook> hooks;
+	private final List<AddContactHook> addHooks;
 	private final List<RemoveContactHook> removeHooks;
 	@Inject
 	ContactManagerImpl(DatabaseComponent db, KeyManager keyManager) {
 		this.db = db;
 		this.keyManager = keyManager;
-		hooks = new CopyOnWriteArrayList<>();
+		addHooks = new CopyOnWriteArrayList<>();
 		removeHooks = new CopyOnWriteArrayList<>();
 	}
 	@Override
-	public void registerContactHook(ContactHook hook) {
+	public void registerAddContactHook(AddContactHook hook) {
-		hooks.add(hook);
+		addHooks.add(hook);
 	}
 	@Override
 	public void registerRemoveContactHook(RemoveContactHook hook) {
 		removeHooks.add(hook);
 	}
 	@Override
 	public ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			SecretKey master, long timestamp, boolean alice, boolean verified,
+			SecretKey master,long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException {
 		ContactId c = db.addContact(txn, remote, local, verified, active);
 		keyManager.addContact(txn, c, master, timestamp, alice);
 		Contact contact = db.getContact(txn, c);
-		for (ContactHook hook : hooks) hook.addingContact(txn, contact);
+		for (AddContactHook hook : addHooks)
-		return c;
+			hook.addingContact(txn, contact);
 	}
 	@Override
 	public ContactId addContact(Transaction txn, Author remote, AuthorId local,
 			boolean verified, boolean active) throws DbException {
 		ContactId c = db.addContact(txn, remote, local, verified, active);
 		Contact contact = db.getContact(txn, c);
 		for (ContactHook hook : hooks) hook.addingContact(txn, contact);
 		return c;
 	}
@@ -157,7 +156,7 @@ class ContactManagerImpl implements ContactManager {
 	@Override
 	public boolean contactExists(AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException {
-		boolean exists;
+		boolean exists = false;
 		Transaction txn = db.startTransaction(true);
 		try {
 			exists = contactExists(txn, remoteAuthorId, localAuthorId);
@@ -172,7 +171,8 @@ class ContactManagerImpl implements ContactManager {
 	public void removeContact(Transaction txn, ContactId c)
 			throws DbException {
 		Contact contact = db.getContact(txn, c);
-		for (ContactHook hook : hooks) hook.removingContact(txn, contact);
+		for (RemoveContactHook hook : removeHooks)
 			hook.removingContact(txn, contact);
 		db.removeContact(txn, c);
 	}
--- a/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java
@@ -205,12 +205,12 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 	@Override
-	public boolean verifySignature(byte[] signature, String label,
+	public boolean verify(String label, byte[] signedData, byte[] publicKey,
-			byte[] signed, byte[] publicKey) throws GeneralSecurityException {
+			byte[] signature) throws GeneralSecurityException {
 		PublicKey key = signatureKeyParser.parsePublicKey(publicKey);
 		Signature sig = new EdSignature();
 		sig.initVerify(key);
-		updateSignature(sig, label, signed);
+		updateSignature(sig, label, signedData);
 		return sig.verify(signature);
 	}
@@ -262,17 +262,6 @@ class CryptoComponentImpl implements CryptoComponent {
 		return output;
 	}
 	@Override
 	public boolean verifyMac(byte[] mac, String label, SecretKey macKey,
 			byte[]... inputs) {
 		byte[] expected = mac(label, macKey, inputs);
 		if (mac.length != expected.length) return false;
 		// Constant-time comparison
 		int cmp = 0;
 		for (int i = 0; i < mac.length; i++) cmp |= mac[i] ^ expected[i];
 		return cmp == 0;
 	}
 	@Override
 	public byte[] encryptWithPassword(byte[] input, String password) {
 		AuthenticatedCipher cipher = new XSalsa20Poly1305AuthenticatedCipher();
--- a/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoExecutorModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoExecutorModule.java
@@ -1,67 +0,0 @@
 package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.TimeLoggingExecutor;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionHandler;
 import java.util.concurrent.ThreadPoolExecutor;
 import javax.inject.Inject;
 import javax.inject.Singleton;
 import dagger.Module;
 import dagger.Provides;
 import static java.util.concurrent.TimeUnit.SECONDS;
@Module
 public class CryptoExecutorModule {
 	public static class EagerSingletons {
 		@Inject
 		@CryptoExecutor
 		ExecutorService cryptoExecutor;
 	}
 	/**
 	 * The maximum number of executor threads.
 	 * <p>
 	 * The number of available processors can change during the lifetime of the
 	 * JVM, so this is just a reasonable guess.
 	 */
 	private static final int MAX_EXECUTOR_THREADS =
 			Math.max(1, Runtime.getRuntime().availableProcessors() - 1);
 	private final ExecutorService cryptoExecutor;
 	public CryptoExecutorModule() {
 		// Use an unbounded queue
 		BlockingQueue<Runnable> queue = new LinkedBlockingQueue<>();
 		// Discard tasks that are submitted during shutdown
 		RejectedExecutionHandler policy =
 				new ThreadPoolExecutor.DiscardPolicy();
 		// Create a limited # of threads and keep them in the pool for 60 secs
 		cryptoExecutor = new TimeLoggingExecutor("CryptoExecutor", 0,
 				MAX_EXECUTOR_THREADS, 60, SECONDS, queue, policy);
 	}
 	@Provides
 	@Singleton
 	@CryptoExecutor
 	ExecutorService provideCryptoExecutorService(
 			LifecycleManager lifecycleManager) {
 		lifecycleManager.registerForShutdown(cryptoExecutor);
 		return cryptoExecutor;
 	}
 	@Provides
 	@CryptoExecutor
 	Executor provideCryptoExecutor() {
 		return cryptoExecutor;
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoModule.java
@@ -1,24 +1,64 @@
 package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.TimeLoggingExecutor;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
 import org.briarproject.bramble.api.crypto.StreamDecrypterFactory;
 import org.briarproject.bramble.api.crypto.StreamEncrypterFactory;
 import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
 import java.security.SecureRandom;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionHandler;
 import java.util.concurrent.ThreadPoolExecutor;
 import javax.inject.Inject;
 import javax.inject.Provider;
 import javax.inject.Singleton;
 import dagger.Module;
 import dagger.Provides;
 import static java.util.concurrent.TimeUnit.SECONDS;
@Module
 public class CryptoModule {
 	public static class EagerSingletons {
 		@Inject
 		@CryptoExecutor
 		ExecutorService cryptoExecutor;
 	}
 	/**
 	 * The maximum number of executor threads.
 	 * <p>
 	 * The number of available processors can change during the lifetime of the
 	 * JVM, so this is just a reasonable guess.
 	 */
 	private static final int MAX_EXECUTOR_THREADS =
 			Math.max(1, Runtime.getRuntime().availableProcessors() - 1);
 	private final ExecutorService cryptoExecutor;
 	public CryptoModule() {
 		// Use an unbounded queue
 		BlockingQueue<Runnable> queue = new LinkedBlockingQueue<>();
 		// Discard tasks that are submitted during shutdown
 		RejectedExecutionHandler policy =
 				new ThreadPoolExecutor.DiscardPolicy();
 		// Create a limited # of threads and keep them in the pool for 60 secs
 		cryptoExecutor = new TimeLoggingExecutor("CryptoExecutor", 0,
 				MAX_EXECUTOR_THREADS, 60, SECONDS, queue, policy);
 	}
 	@Provides
 	AuthenticatedCipher provideAuthenticatedCipher() {
 		return new XSalsa20Poly1305AuthenticatedCipher();
@@ -63,6 +103,21 @@ public class CryptoModule {
 		return keyAgreementCrypto;
 	}
 	@Provides
 	@Singleton
 	@CryptoExecutor
 	ExecutorService getCryptoExecutorService(
 			LifecycleManager lifecycleManager) {
 		lifecycleManager.registerForShutdown(cryptoExecutor);
 		return cryptoExecutor;
 	}
 	@Provides
 	@CryptoExecutor
 	Executor getCryptoExecutor() {
 		return cryptoExecutor;
 	}
 	@Provides
 	SecureRandom getSecureRandom(CryptoComponent crypto) {
 		return crypto.getSecureRandom();
--- a/bramble-core/src/main/java/org/briarproject/bramble/crypto/Signature.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/crypto/Signature.java
@@ -10,37 +10,37 @@ import java.security.GeneralSecurityException;
 interface Signature {
 	/**
-	 * @see java.security.Signature#initSign(java.security.PrivateKey)
+	 * @see {@link java.security.Signature#initSign(java.security.PrivateKey)}
 	 */
 	void initSign(PrivateKey k) throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#initVerify(java.security.PublicKey)
+	 * @see {@link java.security.Signature#initVerify(java.security.PublicKey)}
 	 */
 	void initVerify(PublicKey k) throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#update(byte)
+	 * @see {@link java.security.Signature#update(byte)}
 	 */
 	void update(byte b) throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#update(byte[])
+	 * @see {@link java.security.Signature#update(byte[])}
 	 */
 	void update(byte[] b) throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#update(byte[], int, int)
+	 * @see {@link java.security.Signature#update(byte[], int, int)}
 	 */
 	void update(byte[] b, int off, int len) throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#sign()}
+	 * @see {@link java.security.Signature#sign()}
 	 */
 	byte[] sign() throws GeneralSecurityException;
 	/**
-	 * @see java.security.Signature#verify(byte[])
+	 * @see {@link java.security.Signature#verify(byte[])}
 	 */
 	boolean verify(byte[] signature) throws GeneralSecurityException;
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java
@@ -36,8 +36,7 @@ class TransportCryptoImpl implements TransportCrypto {
 	@Override
 	public TransportKeys deriveTransportKeys(TransportId t,
-			SecretKey master, long rotationPeriod, boolean alice,
+			SecretKey master, long rotationPeriod, boolean alice) {
 			boolean active) {
 		// Keys for the previous period are derived from the master secret
 		SecretKey inTagPrev = deriveTagKey(master, t, !alice);
 		SecretKey inHeaderPrev = deriveHeaderKey(master, t, !alice);
@@ -58,7 +57,7 @@ class TransportCryptoImpl implements TransportCrypto {
 		IncomingKeys inNext = new IncomingKeys(inTagNext, inHeaderNext,
 				rotationPeriod + 1);
 		OutgoingKeys outCurr = new OutgoingKeys(outTagCurr, outHeaderCurr,
-				rotationPeriod, active);
+				rotationPeriod);
 		// Collect and return the keys
 		return new TransportKeys(t, inPrev, inCurr, inNext, outCurr);
 	}
@@ -72,7 +71,6 @@ class TransportCryptoImpl implements TransportCrypto {
 		IncomingKeys inNext = k.getNextIncomingKeys();
 		OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
 		long startPeriod = outCurr.getRotationPeriod();
 		boolean active = outCurr.isActive();
 		// Rotate the keys
 		for (long p = startPeriod + 1; p <= rotationPeriod; p++) {
 			inPrev = inCurr;
@@ -82,7 +80,7 @@ class TransportCryptoImpl implements TransportCrypto {
 			inNext = new IncomingKeys(inNextTag, inNextHeader, p + 1);
 			SecretKey outCurrTag = rotateKey(outCurr.getTagKey(), p);
 			SecretKey outCurrHeader = rotateKey(outCurr.getHeaderKey(), p);
-			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p, active);
+			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p);
 		}
 		// Collect and return the keys
 		return new TransportKeys(k.getTransportId(), inPrev, inCurr, inNext,
--- a/bramble-core/src/main/java/org/briarproject/bramble/db/Database.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/db/Database.java
@@ -21,8 +21,6 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.ValidationManager.State;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import java.util.Collection;
@@ -34,8 +32,8 @@ import javax.annotation.Nullable;
 * A low-level interface to the database (DatabaseComponent provides a
 * high-level interface). Most operations take a transaction argument, which is
 * obtained by calling {@link #startTransaction()}. Every transaction must be
- * terminated by calling either {@link #abortTransaction(Object) abortTransaction(T)} or
+ * terminated by calling either {@link #abortTransaction(T)} or
- * {@link #commitTransaction(Object) commitTransaction(T)}, even if an exception is thrown.
+ * {@link #commitTransaction(T)}, even if an exception is thrown.
 */
@NotNullByDefault
 interface Database<T> {
@@ -107,11 +105,10 @@ interface Database<T> {
 			@Nullable ContactId sender) throws DbException;
 	/**
-	 * Adds a dependency between two messages, where the dependent message is
+	 * Adds a dependency between two messages in the given group.
 	 * in the given state.
 	 */
-	void addMessageDependency(T txn, Message dependent, MessageId dependency,
+	void addMessageDependency(T txn, GroupId g, MessageId dependent,
-			State dependentState) throws DbException;
+			MessageId dependency) throws DbException;
 	/**
 	 * Records that a message has been offered by the given contact.
@@ -125,16 +122,9 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Stores the given transport keys, optionally binding them to the given
+	 * Stores transport keys for a newly added contact.
 	 * contact, and returns a key set ID.
 	 */
-	KeySetId addTransportKeys(T txn, @Nullable ContactId c, TransportKeys k)
+	void addTransportKeys(T txn, ContactId c, TransportKeys k)
 			throws DbException;
 	/**
 	 * Binds the given keys for the given transport to the given contact.
 	 */
 	void bindTransportKeys(T txn, ContactId c, TransportId t, KeySetId k)
 			throws DbException;
 	/**
@@ -266,8 +256,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<Group> getGroups(T txn, ClientId c, int majorVersion)
+	Collection<Group> getGroups(T txn, ClientId c) throws DbException;
 			throws DbException;
 	/**
 	 * Returns the given group's visibility to the given contact, or
@@ -303,8 +292,10 @@ interface Database<T> {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
-	 * For missing dependencies and dependencies in other groups, the state
+	 * Missing dependencies have the state {@link State UNKNOWN}.
-	 * {@link State UNKNOWN} is returned.
+	 * Dependencies in other groups have the state {@link State INVALID}.
 	 * Note that these states are not set on the dependencies themselves; the
 	 * returned states should only be taken in the context of the given message.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -312,9 +303,9 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Returns the IDs and states of all dependents of the given message.
+	 * Returns all IDs and states of all dependents of the given message.
-	 * Dependents in other groups are not returned. If the given message is
+	 * Messages in other groups that declare a dependency on the given message
-	 * missing, no dependents are returned.
+	 * will be returned even though such dependencies are invalid.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -322,16 +313,16 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Returns the IDs of all delivered messages in the given group.
+	 * Returns the IDs of all messages in the given group.
 	 * <p/>
 	 * Read-only.
 	 */
 	Collection<MessageId> getMessageIds(T txn, GroupId g) throws DbException;
 	/**
-	 * Returns the IDs of any delivered messages in the given group with
+	 * Returns the IDs of any messages in the given group with metadata
-	 * metadata that matches all entries in the given query. If the query is
+	 * matching all entries in the given query. If the query is empty, the IDs
-	 * empty, the IDs of all delivered messages are returned.
+	 * of all messages are returned.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -347,9 +338,9 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Returns the metadata for any delivered messages in the given group with
+	 * Returns the metadata for any messages in the given group with metadata
-	 * metadata that matches all entries in the given query. If the query is
+	 * matching all entries in the given query. If the query is empty, the
-	 * empty, the metadata for all delivered messages is returned.
+	 * metadata for all messages is returned.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -357,8 +348,7 @@ interface Database<T> {
 			Metadata query) throws DbException;
 	/**
-	 * Returns the metadata for the given delivered or pending message.
+	 * Returns the metadata for the given delivered message.
 	 * This is only meant to be used by the ValidationManager.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -366,7 +356,7 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Returns the metadata for the given delivered message.
+	 * Returns the metadata for the given message.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -380,8 +370,8 @@ interface Database<T> {
 	State getMessageState(T txn, MessageId m) throws DbException;
 	/**
-	 * Returns the status of all delivered messages in the given group with
+	 * Returns the status of all messages in the given group with respect
-	 * respect to the given contact.
+	 * to the given contact.
 	 * <p/>
 	 * Read-only.
 	 */
@@ -389,13 +379,11 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Returns the status of the given delivered message with respect to the
+	 * Returns the status of the given message with respect to the given
 	 * given contact, or null if the message's group is invisible to the
 	 * contact.
 	 * <p/>
 	 * Read-only.
 	 */
 	@Nullable
 	MessageStatus getMessageStatus(T txn, ContactId c, MessageId m)
 			throws DbException;
@@ -499,14 +487,15 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<KeySet> getTransportKeys(T txn, TransportId t)
+	Map<ContactId, TransportKeys> getTransportKeys(T txn, TransportId t)
 			throws DbException;
 	/**
-	 * Increments the outgoing stream counter for the given transport keys.
+	 * Increments the outgoing stream counter for the given contact and
 	 * transport in the given rotation period.
 	 */
-	void incrementStreamCounter(T txn, TransportId t, KeySetId k)
+	void incrementStreamCounter(T txn, ContactId c, TransportId t,
-			throws DbException;
+			long rotationPeriod) throws DbException;
 	/**
 	 * Marks the given messages as not needing to be acknowledged to the
@@ -596,12 +585,6 @@ interface Database<T> {
 	 */
 	void removeTransport(T txn, TransportId t) throws DbException;
 	/**
 	 * Removes the given transport keys from the database.
 	 */
 	void removeTransportKeys(T txn, TransportId t, KeySetId k)
 			throws DbException;
 	/**
 	 * Resets the transmission count and expiry time of the given message with
 	 * respect to the given contact.
@@ -637,18 +620,12 @@ interface Database<T> {
 	void setMessageState(T txn, MessageId m, State state) throws DbException;
 	/**
-	 * Sets the reordering window for the given key set and transport in the
+	 * Sets the reordering window for the given contact and transport in the
 	 * given rotation period.
 	 */
-	void setReorderingWindow(T txn, KeySetId k, TransportId t,
+	void setReorderingWindow(T txn, ContactId c, TransportId t,
 			long rotationPeriod, long base, byte[] bitmap) throws DbException;
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
 	void setTransportKeysActive(T txn, TransportId t, KeySetId k)
 		throws DbException;
 	/**
 	 * Updates the transmission count and expiry time of the given message
 	 * with respect to the given contact, using the latency of the transport
@@ -658,7 +635,8 @@ interface Database<T> {
 			throws DbException;
 	/**
-	 * Updates the given transport keys following key rotation.
+	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
-	void updateTransportKeys(T txn, KeySet ks) throws DbException;
+	void updateTransportKeys(T txn, Map<ContactId, TransportKeys> keys)
 			throws DbException;
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java
@@ -51,15 +51,15 @@ import org.briarproject.bramble.api.sync.event.MessageToAckEvent;
 import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.logging.Logger;
@@ -234,27 +234,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 	@Override
-	public KeySetId addTransportKeys(Transaction transaction,
+	public void addTransportKeys(Transaction transaction, ContactId c,
-			@Nullable ContactId c, TransportKeys k) throws DbException {
+			TransportKeys k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (c != null && !db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		if (!db.containsTransport(txn, k.getTransportId()))
 			throw new NoSuchTransportException();
 		return db.addTransportKeys(txn, c, k);
 	}
 	@Override
 	public void bindTransportKeys(Transaction transaction, ContactId c,
 			TransportId t, KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		if (!db.containsTransport(txn, t))
+		if (!db.containsTransport(txn, k.getTransportId()))
 			throw new NoSuchTransportException();
-		db.bindTransportKeys(txn, c, t, k);
+		db.addTransportKeys(txn, c, k);
 	}
 	@Override
@@ -435,10 +423,10 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 	@Override
-	public Collection<Group> getGroups(Transaction transaction, ClientId c,
+	public Collection<Group> getGroups(Transaction transaction, ClientId c)
-			int majorVersion) throws DbException {
+			throws DbException {
 		T txn = unbox(transaction);
-		return db.getGroups(txn, c, majorVersion);
+		return db.getGroups(txn, c);
 	}
 	@Override
@@ -466,15 +454,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getLocalAuthors(txn);
 	}
 	@Override
 	public Collection<MessageId> getMessageIds(Transaction transaction,
 			GroupId g) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsGroup(txn, g))
 			throw new NoSuchGroupException();
 		return db.getMessageIds(txn, g);
 	}
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Transaction transaction)
 			throws DbException {
@@ -560,13 +539,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchContactException();
 		if (!db.containsGroup(txn, g))
 			throw new NoSuchGroupException();
 		if (db.getGroupVisibility(txn, c, g) == INVISIBLE) {
 			// No status rows exist - return default statuses
 			Collection<MessageStatus> statuses = new ArrayList<>();
 			for (MessageId m : db.getMessageIds(txn, g))
 				statuses.add(new MessageStatus(m, c, false, false));
 			return statuses;
 		}
 		return db.getMessageStatus(txn, c, g);
 	}
@@ -578,9 +550,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchContactException();
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
-		MessageStatus status = db.getMessageStatus(txn, c, m);
+		return db.getMessageStatus(txn, c, m);
 		if (status == null) return new MessageStatus(m, c, false, false);
 		return status;
 	}
 	@Override
@@ -616,8 +586,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 	@Override
-	public Collection<KeySet> getTransportKeys(Transaction transaction,
+	public Map<ContactId, TransportKeys> getTransportKeys(
-			TransportId t) throws DbException {
+			Transaction transaction, TransportId t) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
 			throw new NoSuchTransportException();
@@ -625,13 +595,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 	@Override
-	public void incrementStreamCounter(Transaction transaction, TransportId t,
+	public void incrementStreamCounter(Transaction transaction, ContactId c,
-			KeySetId k) throws DbException {
+			TransportId t, long rotationPeriod) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		if (!db.containsTransport(txn, t))
 			throw new NoSuchTransportException();
-		db.incrementStreamCounter(txn, t, k);
+		db.incrementStreamCounter(txn, c, t, rotationPeriod);
 	}
 	@Override
@@ -793,7 +765,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
 		// TODO: Don't allow messages with dependents to be removed
 		db.removeMessage(txn, m);
 	}
@@ -807,16 +778,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.removeTransport(txn, t);
 	}
 	@Override
 	public void removeTransportKeys(Transaction transaction,
 			TransportId t, KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
 			throw new NoSuchTransportException();
 		db.removeTransportKeys(txn, t, k);
 	}
 	@Override
 	public void setContactVerified(Transaction transaction, ContactId c)
 			throws DbException {
@@ -889,41 +850,39 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, dependent.getId()))
 			throw new NoSuchMessageException();
 		State dependentState = db.getMessageState(txn, dependent.getId());
 		for (MessageId dependency : dependencies) {
-			db.addMessageDependency(txn, dependent, dependency, dependentState);
+			db.addMessageDependency(txn, dependent.getGroupId(),
 					dependent.getId(), dependency);
 		}
 	}
 	@Override
-	public void setReorderingWindow(Transaction transaction, KeySetId k,
+	public void setReorderingWindow(Transaction transaction, ContactId c,
 			TransportId t, long rotationPeriod, long base, byte[] bitmap)
 			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		if (!db.containsTransport(txn, t))
 			throw new NoSuchTransportException();
-		db.setReorderingWindow(txn, k, t, rotationPeriod, base, bitmap);
+		db.setReorderingWindow(txn, c, t, rotationPeriod, base, bitmap);
 	}
 	@Override
 	public void setTransportKeysActive(Transaction transaction, TransportId t,
 			KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
 			throw new NoSuchTransportException();
 		db.setTransportKeysActive(txn, t, k);
 	}
 	@Override
 	public void updateTransportKeys(Transaction transaction,
-			Collection<KeySet> keys) throws DbException {
+			Map<ContactId, TransportKeys> keys) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
-		for (KeySet ks : keys) {
+		Map<ContactId, TransportKeys> filtered = new HashMap<>();
-			TransportId t = ks.getTransportKeys().getTransportId();
+		for (Entry<ContactId, TransportKeys> e : keys.entrySet()) {
-			if (db.containsTransport(txn, t)) db.updateTransportKeys(txn, ks);
+			ContactId c = e.getKey();
 			TransportKeys k = e.getValue();
 			if (db.containsContact(txn, c)
 					&& db.containsTransport(txn, k.getTransportId())) {
 				filtered.put(c, k);
 			}
 		}
 		db.updateTransportKeys(txn, filtered);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java
@@ -25,8 +25,6 @@ import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.ValidationManager.State;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -52,7 +50,6 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import static java.sql.Types.INTEGER;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
@@ -60,6 +57,7 @@ import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
@@ -74,12 +72,7 @@ import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
 abstract class JdbcDatabase implements Database<Connection> {
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 38;
+	static final int CODE_SCHEMA_VERSION = 35;
 	// Rotation period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
 	private static final int OFFSET_CURR = 0;
 	private static final int OFFSET_NEXT = 1;
 	private static final String CREATE_SETTINGS =
 			"CREATE TABLE settings"
@@ -117,7 +110,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 			"CREATE TABLE groups"
 					+ " (groupId _HASH NOT NULL,"
 					+ " clientId _STRING NOT NULL,"
 					+ " majorVersion INT NOT NULL,"
 					+ " descriptor _BINARY NOT NULL,"
 					+ " PRIMARY KEY (groupId))";
@@ -178,10 +170,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " (groupId _HASH NOT NULL,"
 					+ " messageId _HASH NOT NULL,"
 					+ " dependencyId _HASH NOT NULL," // Not a foreign key
 					+ " messageState INT NOT NULL," // Denormalised
 					// Denormalised, null if dependency is missing or in a
 					// different group
 					+ " dependencyState INT,"
 					+ " FOREIGN KEY (groupId)"
 					+ " REFERENCES groups (groupId)"
 					+ " ON DELETE CASCADE,"
@@ -231,63 +219,51 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " maxLatency INT NOT NULL,"
 					+ " PRIMARY KEY (transportId))";
 	private static final String CREATE_OUTGOING_KEYS =
 			"CREATE TABLE outgoingKeys"
 					+ " (transportId _STRING NOT NULL,"
 					+ " keySetId _COUNTER,"
 					+ " rotationPeriod BIGINT NOT NULL,"
 					+ " contactId INT," // Null if keys are not bound
 					+ " tagKey _SECRET NOT NULL,"
 					+ " headerKey _SECRET NOT NULL,"
 					+ " stream BIGINT NOT NULL,"
 					+ " active BOOLEAN NOT NULL,"
 					+ " PRIMARY KEY (transportId, keySetId),"
 					+ " FOREIGN KEY (transportId)"
 					+ " REFERENCES transports (transportId)"
 					+ " ON DELETE CASCADE,"
 					+ " UNIQUE (keySetId),"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
 					+ " ON DELETE CASCADE)";
 	private static final String CREATE_INCOMING_KEYS =
 			"CREATE TABLE incomingKeys"
-					+ " (transportId _STRING NOT NULL,"
+					+ " (contactId INT NOT NULL,"
-					+ " keySetId INT NOT NULL,"
+					+ " transportId _STRING NOT NULL,"
 					+ " rotationPeriod BIGINT NOT NULL,"
 					+ " contactId INT," // Null if keys are not bound
 					+ " tagKey _SECRET NOT NULL,"
 					+ " headerKey _SECRET NOT NULL,"
 					+ " base BIGINT NOT NULL,"
 					+ " bitmap _BINARY NOT NULL,"
-					+ " periodOffset INT NOT NULL,"
+					+ " PRIMARY KEY (contactId, transportId, rotationPeriod),"
 					+ " PRIMARY KEY (transportId, keySetId, periodOffset),"
 					+ " FOREIGN KEY (transportId)"
 					+ " REFERENCES transports (transportId)"
 					+ " ON DELETE CASCADE,"
 					+ " FOREIGN KEY (keySetId)"
 					+ " REFERENCES outgoingKeys (keySetId)"
 					+ " ON DELETE CASCADE,"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
 					+ " ON DELETE CASCADE,"
 					+ " FOREIGN KEY (transportId)"
 					+ " REFERENCES transports (transportId)"
 					+ " ON DELETE CASCADE)";
 	private static final String CREATE_OUTGOING_KEYS =
 			"CREATE TABLE outgoingKeys"
 					+ " (contactId INT NOT NULL,"
 					+ " transportId _STRING NOT NULL,"
 					+ " rotationPeriod BIGINT NOT NULL,"
 					+ " tagKey _SECRET NOT NULL,"
 					+ " headerKey _SECRET NOT NULL,"
 					+ " stream BIGINT NOT NULL,"
 					+ " PRIMARY KEY (contactId, transportId),"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
 					+ " ON DELETE CASCADE,"
 					+ " FOREIGN KEY (transportId)"
 					+ " REFERENCES transports (transportId)"
 					+ " ON DELETE CASCADE)";
 	private static final String INDEX_CONTACTS_BY_AUTHOR_ID =
 			"CREATE INDEX IF NOT EXISTS contactsByAuthorId"
 					+ " ON contacts (authorId)";
-	private static final String INDEX_GROUPS_BY_CLIENT_ID_MAJOR_VERSION =
+	private static final String INDEX_GROUPS_BY_CLIENT_ID =
-			"CREATE INDEX IF NOT EXISTS groupsByClientIdMajorVersion"
+			"CREATE INDEX IF NOT EXISTS groupsByClientId"
-					+ " ON groups (clientId, majorVersion)";
+					+ " ON groups (clientId)";
 	private static final String INDEX_MESSAGE_METADATA_BY_GROUP_ID_STATE =
 			"CREATE INDEX IF NOT EXISTS messageMetadataByGroupIdState"
 					+ " ON messageMetadata (groupId, state)";
 	private static final String INDEX_MESSAGE_DEPENDENCIES_BY_DEPENDENCY_ID =
 			"CREATE INDEX IF NOT EXISTS messageDependenciesByDependencyId"
 					+ " ON messageDependencies (dependencyId)";
 	private static final String INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID =
 			"CREATE INDEX IF NOT EXISTS statusesByContactIdGroupId"
 					+ " ON statuses (contactId, groupId)";
@@ -431,8 +407,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(insertTypeNames(CREATE_OFFERS));
 			s.executeUpdate(insertTypeNames(CREATE_STATUSES));
 			s.executeUpdate(insertTypeNames(CREATE_TRANSPORTS));
 			s.executeUpdate(insertTypeNames(CREATE_OUTGOING_KEYS));
 			s.executeUpdate(insertTypeNames(CREATE_INCOMING_KEYS));
 			s.executeUpdate(insertTypeNames(CREATE_OUTGOING_KEYS));
 			s.close();
 		} catch (SQLException e) {
 			tryToClose(s);
@@ -445,9 +421,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			s = txn.createStatement();
 			s.executeUpdate(INDEX_CONTACTS_BY_AUTHOR_ID);
-			s.executeUpdate(INDEX_GROUPS_BY_CLIENT_ID_MAJOR_VERSION);
+			s.executeUpdate(INDEX_GROUPS_BY_CLIENT_ID);
 			s.executeUpdate(INDEX_MESSAGE_METADATA_BY_GROUP_ID_STATE);
 			s.executeUpdate(INDEX_MESSAGE_DEPENDENCIES_BY_DEPENDENCY_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP);
 			s.close();
@@ -613,14 +588,12 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public void addGroup(Connection txn, Group g) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "INSERT INTO groups"
+			String sql = "INSERT INTO groups (groupId, clientId, descriptor)"
-					+ " (groupId, clientId, majorVersion, descriptor)"
+					+ " VALUES (?, ?, ?)";
 					+ " VALUES (?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getId().getBytes());
 			ps.setString(2, g.getClientId().getString());
-			ps.setInt(3, g.getMajorVersion());
+			ps.setBytes(3, g.getDescriptor());
 			ps.setBytes(4, g.getDescriptor());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -742,17 +715,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 						m.getLength(), state, e.getValue(), messageShared,
 						false, seen);
 			}
 			// Update denormalised column in messageDependencies if dependency
 			// is in same group as dependent
 			sql = "UPDATE messageDependencies SET dependencyState = ?"
 					+ " WHERE groupId = ? AND dependencyId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			ps.setBytes(2, m.getGroupId().getBytes());
 			ps.setBytes(3, m.getId().getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -822,42 +784,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public void addMessageDependency(Connection txn, Message dependent,
+	public void addMessageDependency(Connection txn, GroupId g,
-			MessageId dependency, State dependentState) throws DbException {
+			MessageId dependent, MessageId dependency) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			// Get state of dependency if present and in same group as dependent
+			String sql = "INSERT INTO messageDependencies"
-			String sql = "SELECT state FROM messages"
+					+ " (groupId, messageId, dependencyId)"
-					+ " WHERE messageId = ? AND groupId = ?";
+					+ " VALUES (?, ?, ?)";
 			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, dependency.getBytes());
+			ps.setBytes(1, g.getBytes());
-			ps.setBytes(2, dependent.getGroupId().getBytes());
+			ps.setBytes(2, dependent.getBytes());
 			rs = ps.executeQuery();
 			State dependencyState = null;
 			if (rs.next()) {
 				dependencyState = State.fromValue(rs.getInt(1));
 				if (rs.next()) throw new DbStateException();
 			}
 			rs.close();
 			ps.close();
 			// Create messageDependencies row
 			sql = "INSERT INTO messageDependencies"
 					+ " (groupId, messageId, dependencyId, messageState,"
 					+ " dependencyState)"
 					+ " VALUES (?, ?, ?, ? ,?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, dependent.getGroupId().getBytes());
 			ps.setBytes(2, dependent.getId().getBytes());
 			ps.setBytes(3, dependency.getBytes());
 			ps.setInt(4, dependentState.getValue());
 			if (dependencyState == null) ps.setNull(5, INTEGER);
 			else ps.setInt(5, dependencyState.getValue());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(rs);
 			tryToClose(ps);
 			throw new DbException(e);
 		}
@@ -883,108 +824,60 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public KeySetId addTransportKeys(Connection txn, @Nullable ContactId c,
+	public void addTransportKeys(Connection txn, ContactId c, TransportKeys k)
-			TransportKeys k) throws DbException {
+			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			// Store the outgoing keys
+			// Store the incoming keys
-			String sql = "INSERT INTO outgoingKeys (contactId, transportId,"
+			String sql = "INSERT INTO incomingKeys (contactId, transportId,"
-					+ " rotationPeriod, tagKey, headerKey, stream, active)"
+					+ " rotationPeriod, tagKey, headerKey, base, bitmap)"
 					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
-			if (c == null) ps.setNull(1, INTEGER);
+			ps.setInt(1, c.getInt());
 			else ps.setInt(1, c.getInt());
 			ps.setString(2, k.getTransportId().getString());
 			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
 			ps.setLong(3, outCurr.getRotationPeriod());
 			ps.setBytes(4, outCurr.getTagKey().getBytes());
 			ps.setBytes(5, outCurr.getHeaderKey().getBytes());
 			ps.setLong(6, outCurr.getStreamCounter());
 			ps.setBoolean(7, outCurr.isActive());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 			// Get the new (highest) key set ID
 			sql = "SELECT keySetId FROM outgoingKeys"
 					+ " ORDER BY keySetId DESC LIMIT 1";
 			ps = txn.prepareStatement(sql);
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
 			KeySetId keySetId = new KeySetId(rs.getInt(1));
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
 			// Store the incoming keys
 			sql = "INSERT INTO incomingKeys (keySetId, contactId, transportId,"
 					+ " rotationPeriod, tagKey, headerKey, base, bitmap,"
 					+ " periodOffset)"
 					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, keySetId.getInt());
 			if (c == null) ps.setNull(2, INTEGER);
 			else ps.setInt(2, c.getInt());
 			ps.setString(3, k.getTransportId().getString());
 			// Previous rotation period
 			IncomingKeys inPrev = k.getPreviousIncomingKeys();
-			ps.setLong(4, inPrev.getRotationPeriod());
+			ps.setLong(3, inPrev.getRotationPeriod());
-			ps.setBytes(5, inPrev.getTagKey().getBytes());
+			ps.setBytes(4, inPrev.getTagKey().getBytes());
-			ps.setBytes(6, inPrev.getHeaderKey().getBytes());
+			ps.setBytes(5, inPrev.getHeaderKey().getBytes());
-			ps.setLong(7, inPrev.getWindowBase());
+			ps.setLong(6, inPrev.getWindowBase());
-			ps.setBytes(8, inPrev.getWindowBitmap());
+			ps.setBytes(7, inPrev.getWindowBitmap());
 			ps.setInt(9, OFFSET_PREV);
 			ps.addBatch();
 			// Current rotation period
 			IncomingKeys inCurr = k.getCurrentIncomingKeys();
-			ps.setLong(4, inCurr.getRotationPeriod());
+			ps.setLong(3, inCurr.getRotationPeriod());
-			ps.setBytes(5, inCurr.getTagKey().getBytes());
+			ps.setBytes(4, inCurr.getTagKey().getBytes());
-			ps.setBytes(6, inCurr.getHeaderKey().getBytes());
+			ps.setBytes(5, inCurr.getHeaderKey().getBytes());
-			ps.setLong(7, inCurr.getWindowBase());
+			ps.setLong(6, inCurr.getWindowBase());
-			ps.setBytes(8, inCurr.getWindowBitmap());
+			ps.setBytes(7, inCurr.getWindowBitmap());
 			ps.setInt(9, OFFSET_CURR);
 			ps.addBatch();
 			// Next rotation period
 			IncomingKeys inNext = k.getNextIncomingKeys();
-			ps.setLong(4, inNext.getRotationPeriod());
+			ps.setLong(3, inNext.getRotationPeriod());
-			ps.setBytes(5, inNext.getTagKey().getBytes());
+			ps.setBytes(4, inNext.getTagKey().getBytes());
-			ps.setBytes(6, inNext.getHeaderKey().getBytes());
+			ps.setBytes(5, inNext.getHeaderKey().getBytes());
-			ps.setLong(7, inNext.getWindowBase());
+			ps.setLong(6, inNext.getWindowBase());
-			ps.setBytes(8, inNext.getWindowBitmap());
+			ps.setBytes(7, inNext.getWindowBitmap());
 			ps.setInt(9, OFFSET_NEXT);
 			ps.addBatch();
 			int[] batchAffected = ps.executeBatch();
 			if (batchAffected.length != 3) throw new DbStateException();
 			for (int rows : batchAffected)
 				if (rows != 1) throw new DbStateException();
 			ps.close();
-			return keySetId;
+			// Store the outgoing keys
-		} catch (SQLException e) {
+			sql = "INSERT INTO outgoingKeys (contactId, transportId,"
-			tryToClose(rs);
+					+ " rotationPeriod, tagKey, headerKey, stream)"
-			tryToClose(ps);
+					+ " VALUES (?, ?, ?, ?, ?, ?)";
 			throw new DbException(e);
 		}
 	}
 	@Override
 	public void bindTransportKeys(Connection txn, ContactId c, TransportId t,
 			KeySetId k) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET contactId = ?"
 					+ " WHERE keySetId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
-			ps.setInt(2, k.getInt());
+			ps.setString(2, k.getTransportId().getString());
 			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
 			ps.setLong(3, outCurr.getRotationPeriod());
 			ps.setBytes(4, outCurr.getTagKey().getBytes());
 			ps.setBytes(5, outCurr.getHeaderKey().getBytes());
 			ps.setLong(6, outCurr.getStreamCounter());
 			int affected = ps.executeUpdate();
-			if (affected < 0) throw new DbStateException();
+			if (affected != 1) throw new DbStateException();
 			ps.close();
 			sql = "UPDATE incomingKeys SET contactId = ?"
 					+ " WHERE keySetId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setInt(2, k.getInt());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
@@ -1349,18 +1242,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT clientId, majorVersion, descriptor"
+			String sql = "SELECT clientId, descriptor FROM groups"
-					+ " FROM groups WHERE groupId = ?";
+					+ " WHERE groupId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
 			ClientId clientId = new ClientId(rs.getString(1));
-			int majorVersion = rs.getInt(2);
+			byte[] descriptor = rs.getBytes(2);
 			byte[] descriptor = rs.getBytes(3);
 			rs.close();
 			ps.close();
-			return new Group(g, clientId, majorVersion, descriptor);
+			return new Group(g, clientId, descriptor);
 		} catch (SQLException e) {
 			tryToClose(rs);
 			tryToClose(ps);
@@ -1369,22 +1261,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public Collection<Group> getGroups(Connection txn, ClientId c,
+	public Collection<Group> getGroups(Connection txn, ClientId c)
-			int majorVersion) throws DbException {
+			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT groupId, descriptor FROM groups"
-					+ " WHERE clientId = ? AND majorVersion = ?";
+					+ " WHERE clientId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, c.getString());
 			ps.setInt(2, majorVersion);
 			rs = ps.executeQuery();
 			List<Group> groups = new ArrayList<>();
 			while (rs.next()) {
 				GroupId id = new GroupId(rs.getBytes(1));
 				byte[] descriptor = rs.getBytes(2);
-				groups.add(new Group(id, c, majorVersion, descriptor));
+				groups.add(new Group(id, c, descriptor));
 			}
 			rs.close();
 			ps.close();
@@ -1516,11 +1407,32 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT messageId FROM messages"
+			String sql = "SELECT messageId FROM messages WHERE groupId = ?";
 					+ " WHERE groupId = ? AND state = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
-			ps.setInt(2, DELIVERED.getValue());
+			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
 			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
 			rs.close();
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
 			tryToClose(rs);
 			tryToClose(ps);
 			throw new DbException(e);
 		}
 	}
 	private Collection<MessageId> getMessageIds(Connection txn, GroupId g,
 			State state) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId FROM messages"
 					+ " WHERE state = ? AND groupId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			ps.setBytes(2, g.getBytes());
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
 			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
@@ -1538,7 +1450,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public Collection<MessageId> getMessageIds(Connection txn, GroupId g,
 			Metadata query) throws DbException {
 		// If there are no query terms, return all delivered messages
-		if (query.isEmpty()) return getMessageIds(txn, g);
+		if (query.isEmpty()) return getMessageIds(txn, g, DELIVERED);
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -1697,11 +1609,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId, txCount > 0, seen FROM statuses"
-					+ " WHERE groupId = ? AND contactId = ? AND state = ?";
+					+ " WHERE groupId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
 			ps.setInt(2, c.getInt());
 			ps.setInt(3, DELIVERED.getValue());
 			rs = ps.executeQuery();
 			List<MessageStatus> statuses = new ArrayList<>();
 			while (rs.next()) {
@@ -1721,29 +1632,24 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
 	@Nullable
 	public MessageStatus getMessageStatus(Connection txn, ContactId c,
 			MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT txCount > 0, seen FROM statuses"
-					+ " WHERE messageId = ? AND contactId = ? AND state = ?";
+					+ " WHERE messageId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
 			ps.setInt(3, DELIVERED.getValue());
 			rs = ps.executeQuery();
-			MessageStatus status = null;
+			if (!rs.next()) throw new DbStateException();
-			if (rs.next()) {
+			boolean sent = rs.getBoolean(1);
-				boolean sent = rs.getBoolean(1);
+			boolean seen = rs.getBoolean(2);
 				boolean seen = rs.getBoolean(2);
 				status = new MessageStatus(m, c, sent, seen);
 			}
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
-			return status;
+			return new MessageStatus(m, c, sent, seen);
 		} catch (SQLException e) {
 			tryToClose(rs);
 			tryToClose(ps);
@@ -1757,9 +1663,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT dependencyId, dependencyState"
+			String sql = "SELECT d.dependencyId, m.state, d.groupId, m.groupId"
-					+ " FROM messageDependencies"
+					+ " FROM messageDependencies AS d"
-					+ " WHERE messageId = ?";
+					+ " LEFT OUTER JOIN messages AS m"
 					+ " ON d.dependencyId = m.messageId"
 					+ " WHERE d.messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			rs = ps.executeQuery();
@@ -1767,8 +1675,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 			while (rs.next()) {
 				MessageId dependency = new MessageId(rs.getBytes(1));
 				State state = State.fromValue(rs.getInt(2));
-				if (rs.wasNull())
+				if (rs.wasNull()) {
-					state = UNKNOWN; // Missing or in a different group
+					state = UNKNOWN; // Missing dependency
 				} else {
 					GroupId dependentGroupId = new GroupId(rs.getBytes(3));
 					GroupId dependencyGroupId = new GroupId(rs.getBytes(4));
 					if (!dependentGroupId.equals(dependencyGroupId))
 						state = INVALID; // Dependency in another group
 				}
 				dependencies.put(dependency, state);
 			}
 			rs.close();
@@ -1787,12 +1701,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			// Exclude dependencies that are missing or in a different group
+			String sql = "SELECT d.messageId, m.state"
-			// from the dependent
+					+ " FROM messageDependencies AS d"
-			String sql = "SELECT messageId, messageState"
+					+ " JOIN messages AS m"
-					+ " FROM messageDependencies"
+					+ " ON d.messageId = m.messageId"
-					+ " WHERE dependencyId = ?"
+					+ " WHERE dependencyId = ?";
 					+ " AND dependencyState IS NOT NULL";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			rs = ps.executeQuery();
@@ -2131,8 +2044,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public Collection<KeySet> getTransportKeys(Connection txn, TransportId t)
+	public Map<ContactId, TransportKeys> getTransportKeys(Connection txn,
-			throws DbException {
+			TransportId t) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -2141,7 +2054,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " base, bitmap"
 					+ " FROM incomingKeys"
 					+ " WHERE transportId = ?"
-					+ " ORDER BY keySetId, periodOffset";
+					+ " ORDER BY contactId, rotationPeriod";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			rs = ps.executeQuery();
@@ -2158,34 +2071,29 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs.close();
 			ps.close();
 			// Retrieve the outgoing keys in the same order
-			sql = "SELECT keySetId, contactId, rotationPeriod,"
+			sql = "SELECT contactId, rotationPeriod, tagKey, headerKey, stream"
 					+ " tagKey, headerKey, stream, active"
 					+ " FROM outgoingKeys"
 					+ " WHERE transportId = ?"
-					+ " ORDER BY keySetId";
+					+ " ORDER BY contactId, rotationPeriod";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			rs = ps.executeQuery();
-			Collection<KeySet> keys = new ArrayList<>();
+			Map<ContactId, TransportKeys> keys = new HashMap<>();
 			for (int i = 0; rs.next(); i++) {
 				// There should be three times as many incoming keys
 				if (inKeys.size() < (i + 1) * 3) throw new DbStateException();
-				KeySetId keySetId = new KeySetId(rs.getInt(1));
+				ContactId contactId = new ContactId(rs.getInt(1));
-				ContactId contactId = new ContactId(rs.getInt(2));
+				long rotationPeriod = rs.getLong(2);
-				if (rs.wasNull()) contactId = null;
+				SecretKey tagKey = new SecretKey(rs.getBytes(3));
-				long rotationPeriod = rs.getLong(3);
+				SecretKey headerKey = new SecretKey(rs.getBytes(4));
-				SecretKey tagKey = new SecretKey(rs.getBytes(4));
+				long streamCounter = rs.getLong(5);
 				SecretKey headerKey = new SecretKey(rs.getBytes(5));
 				long streamCounter = rs.getLong(6);
 				boolean active = rs.getBoolean(7);
 				OutgoingKeys outCurr = new OutgoingKeys(tagKey, headerKey,
-						rotationPeriod, streamCounter, active);
+						rotationPeriod, streamCounter);
 				IncomingKeys inPrev = inKeys.get(i * 3);
 				IncomingKeys inCurr = inKeys.get(i * 3 + 1);
 				IncomingKeys inNext = inKeys.get(i * 3 + 2);
-				TransportKeys transportKeys = new TransportKeys(t, inPrev,
+				keys.put(contactId, new TransportKeys(t, inPrev, inCurr,
-						inCurr, inNext, outCurr);
+						inNext, outCurr));
 				keys.add(new KeySet(keySetId, contactId, transportKeys));
 			}
 			rs.close();
 			ps.close();
@@ -2198,15 +2106,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public void incrementStreamCounter(Connection txn, TransportId t,
+	public void incrementStreamCounter(Connection txn, ContactId c,
-			KeySetId k) throws DbException {
+			TransportId t, long rotationPeriod) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET stream = stream + 1"
-					+ " WHERE transportId = ? AND keySetId = ?";
+					+ " WHERE contactId = ? AND transportId = ?"
 					+ " AND rotationPeriod = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
+			ps.setInt(1, c.getInt());
-			ps.setInt(2, k.getInt());
+			ps.setString(2, t.getString());
 			ps.setLong(3, rotationPeriod);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -2563,14 +2473,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 			// Remove status rows for the messages in the group
-			sql = "DELETE FROM statuses"
+			for (MessageId m : getMessageIds(txn, g)) removeStatus(txn, c, m);
 					+ " WHERE contactId = ? AND groupId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setBytes(2, g.getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2654,14 +2557,15 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
-	@Override
+	private void removeStatus(Connection txn, ContactId c, MessageId m)
 	public void removeTransport(Connection txn, TransportId t)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "DELETE FROM transports WHERE transportId = ?";
+			String sql = "DELETE FROM statuses"
 					+ " WHERE messageId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
+			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -2672,19 +2576,15 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public void removeTransportKeys(Connection txn, TransportId t, KeySetId k)
+	public void removeTransport(Connection txn, TransportId t)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
-			// Delete any existing outgoing keys - this will also remove any
+			String sql = "DELETE FROM transports WHERE transportId = ?";
 			// incoming keys with the same key set ID
 			String sql = "DELETE FROM outgoingKeys"
 					+ " WHERE transportId = ? AND keySetId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			ps.setInt(2, k.getInt());
 			int affected = ps.executeUpdate();
-			if (affected < 0) throw new DbStateException();
+			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
@@ -2831,25 +2731,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in messageDependencies
 			sql = "UPDATE messageDependencies SET messageState = ?"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			ps.setBytes(2, m.getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in messageDependencies if dependency
 			// is present and in same group as dependent
 			sql = "UPDATE messageDependencies SET dependencyState = ?"
 					+ " WHERE dependencyId = ? AND dependencyState IS NOT NULL";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			ps.setBytes(2, m.getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2857,18 +2738,18 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public void setReorderingWindow(Connection txn, KeySetId k, TransportId t,
+	public void setReorderingWindow(Connection txn, ContactId c, TransportId t,
 			long rotationPeriod, long base, byte[] bitmap) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE incomingKeys SET base = ?, bitmap = ?"
-					+ " WHERE transportId = ? AND keySetId = ?"
+					+ " WHERE contactId = ? AND transportId = ?"
 					+ " AND rotationPeriod = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setLong(1, base);
 			ps.setBytes(2, bitmap);
-			ps.setString(3, t.getString());
+			ps.setInt(3, c.getInt());
-			ps.setInt(4, k.getInt());
+			ps.setString(4, t.getString());
 			ps.setLong(5, rotationPeriod);
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
@@ -2879,25 +2760,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 	@Override
 	public void setTransportKeysActive(Connection txn, TransportId t,
 			KeySetId k) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET active = true"
 					+ " WHERE transportId = ? AND keySetId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			ps.setInt(2, k.getInt());
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
 		}
 	}
 	@Override
 	public void updateExpiryTime(Connection txn, ContactId c, MessageId m,
 			int maxLatency) throws DbException {
@@ -2933,69 +2795,45 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 	@Override
-	public void updateTransportKeys(Connection txn, KeySet ks)
+	public void updateTransportKeys(Connection txn,
-			throws DbException {
+			Map<ContactId, TransportKeys> keys) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			// Update the outgoing keys
+			// Delete any existing incoming keys
-			String sql = "UPDATE outgoingKeys SET rotationPeriod = ?,"
+			String sql = "DELETE FROM incomingKeys"
-					+ " tagKey = ?, headerKey = ?, stream = ?"
+					+ " WHERE contactId = ?"
-					+ " WHERE transportId = ? AND keySetId = ?";
+					+ " AND transportId = ?";
 			ps = txn.prepareStatement(sql);
-			TransportKeys k = ks.getTransportKeys();
+			for (Entry<ContactId, TransportKeys> e : keys.entrySet()) {
-			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
+				ps.setInt(1, e.getKey().getInt());
-			ps.setLong(1, outCurr.getRotationPeriod());
+				ps.setString(2, e.getValue().getTransportId().getString());
-			ps.setBytes(2, outCurr.getTagKey().getBytes());
+				ps.addBatch();
-			ps.setBytes(3, outCurr.getHeaderKey().getBytes());
+			}
 			ps.setLong(4, outCurr.getStreamCounter());
 			ps.setString(5, k.getTransportId().getString());
 			ps.setInt(6, ks.getKeySetId().getInt());
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 			// Update the incoming keys
 			sql = "UPDATE incomingKeys SET rotationPeriod = ?,"
 					+ " tagKey = ?, headerKey = ?, base = ?, bitmap = ?"
 					+ " WHERE transportId = ? AND keySetId = ?"
 					+ " AND periodOffset = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setString(6, k.getTransportId().getString());
 			ps.setInt(7, ks.getKeySetId().getInt());
 			// Previous rotation period
 			IncomingKeys inPrev = k.getPreviousIncomingKeys();
 			ps.setLong(1, inPrev.getRotationPeriod());
 			ps.setBytes(2, inPrev.getTagKey().getBytes());
 			ps.setBytes(3, inPrev.getHeaderKey().getBytes());
 			ps.setLong(4, inPrev.getWindowBase());
 			ps.setBytes(5, inPrev.getWindowBitmap());
 			ps.setInt(8, OFFSET_PREV);
 			ps.addBatch();
 			// Current rotation period
 			IncomingKeys inCurr = k.getCurrentIncomingKeys();
 			ps.setLong(1, inCurr.getRotationPeriod());
 			ps.setBytes(2, inCurr.getTagKey().getBytes());
 			ps.setBytes(3, inCurr.getHeaderKey().getBytes());
 			ps.setLong(4, inCurr.getWindowBase());
 			ps.setBytes(5, inCurr.getWindowBitmap());
 			ps.setInt(8, OFFSET_CURR);
 			ps.addBatch();
 			// Next rotation period
 			IncomingKeys inNext = k.getNextIncomingKeys();
 			ps.setLong(1, inNext.getRotationPeriod());
 			ps.setBytes(2, inNext.getTagKey().getBytes());
 			ps.setBytes(3, inNext.getHeaderKey().getBytes());
 			ps.setLong(4, inNext.getWindowBase());
 			ps.setBytes(5, inNext.getWindowBitmap());
 			ps.setInt(8, OFFSET_NEXT);
 			ps.addBatch();
 			int[] batchAffected = ps.executeBatch();
-			if (batchAffected.length != 3) throw new DbStateException();
+			if (batchAffected.length != keys.size())
-			for (int rows : batchAffected)
+				throw new DbStateException();
-				if (rows < 0 || rows > 1) throw new DbStateException();
+			ps.close();
 			// Delete any existing outgoing keys
 			sql = "DELETE FROM outgoingKeys"
 					+ " WHERE contactId = ?"
 					+ " AND transportId = ?";
 			ps = txn.prepareStatement(sql);
 			for (Entry<ContactId, TransportKeys> e : keys.entrySet()) {
 				ps.setInt(1, e.getKey().getInt());
 				ps.setString(2, e.getValue().getTransportId().getString());
 				ps.addBatch();
 			}
 			batchAffected = ps.executeBatch();
 			if (batchAffected.length != keys.size())
 				throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
 		}
 		// Store the new keys
 		for (Entry<ContactId, TransportKeys> e : keys.entrySet()) {
 			addTransportKeys(txn, e.getKey(), e.getValue());
 		}
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementConnector.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementConnector.java
@@ -13,8 +13,6 @@ import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.IOException;
 import java.io.InputStream;
@@ -46,8 +44,6 @@ class KeyAgreementConnector {
 	private final KeyAgreementCrypto keyAgreementCrypto;
 	private final PluginManager pluginManager;
 	private final ConnectionChooser connectionChooser;
 	private final RecordReaderFactory recordReaderFactory;
 	private final RecordWriterFactory recordWriterFactory;
 	private final List<KeyAgreementListener> listeners =
 			new CopyOnWriteArrayList<>();
@@ -58,15 +54,11 @@ class KeyAgreementConnector {
 	KeyAgreementConnector(Callbacks callbacks,
 			KeyAgreementCrypto keyAgreementCrypto, PluginManager pluginManager,
-			ConnectionChooser connectionChooser,
+			ConnectionChooser connectionChooser) {
 			RecordReaderFactory recordReaderFactory,
 			RecordWriterFactory recordWriterFactory) {
 		this.callbacks = callbacks;
 		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.pluginManager = pluginManager;
 		this.connectionChooser = connectionChooser;
 		this.recordReaderFactory = recordReaderFactory;
 		this.recordWriterFactory = recordWriterFactory;
 	}
 	Payload listen(KeyPair localKeyPair) {
@@ -127,8 +119,7 @@ class KeyAgreementConnector {
 			KeyAgreementConnection chosen =
 					connectionChooser.poll(CONNECTION_TIMEOUT);
 			if (chosen == null) return null;
-			return new KeyAgreementTransport(recordReaderFactory,
+			return new KeyAgreementTransport(chosen);
 					recordWriterFactory, chosen);
 		} catch (InterruptedException e) {
 			LOG.info("Interrupted while waiting for connection");
 			Thread.currentThread().interrupt();
--- a/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskImpl.java
@@ -14,13 +14,10 @@ import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFailedEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStartedEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.IOException;
 import java.util.logging.Logger;
@@ -51,17 +48,14 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 	KeyAgreementTaskImpl(CryptoComponent crypto,
 			KeyAgreementCrypto keyAgreementCrypto, EventBus eventBus,
 			PayloadEncoder payloadEncoder, PluginManager pluginManager,
-			ConnectionChooser connectionChooser,
+			ConnectionChooser connectionChooser) {
 			RecordReaderFactory recordReaderFactory,
 			RecordWriterFactory recordWriterFactory) {
 		this.crypto = crypto;
 		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.eventBus = eventBus;
 		this.payloadEncoder = payloadEncoder;
 		localKeyPair = crypto.generateAgreementKeyPair();
 		connector = new KeyAgreementConnector(this, keyAgreementCrypto,
-				pluginManager, connectionChooser, recordReaderFactory,
+				pluginManager, connectionChooser);
 				recordWriterFactory);
 	}
 	@Override
@@ -77,7 +71,6 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 		if (localPayload != null) {
 			if (remotePayload == null) connector.stopListening();
 			else interrupt();
 			eventBus.broadcast(new KeyAgreementStoppedListeningEvent());
 		}
 	}
--- a/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTransport.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTransport.java
@@ -4,12 +4,9 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.record.Record;
+import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -17,6 +14,8 @@ import java.util.logging.Logger;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.RECORD_HEADER_LENGTH;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.RECORD_HEADER_PAYLOAD_LENGTH_OFFSET;
 import static org.briarproject.bramble.api.keyagreement.RecordTypes.ABORT;
 import static org.briarproject.bramble.api.keyagreement.RecordTypes.CONFIRM;
 import static org.briarproject.bramble.api.keyagreement.RecordTypes.KEY;
@@ -31,17 +30,14 @@ class KeyAgreementTransport {
 			Logger.getLogger(KeyAgreementTransport.class.getName());
 	private final KeyAgreementConnection kac;
-	private final RecordReader reader;
+	private final InputStream in;
-	private final RecordWriter writer;
+	private final OutputStream out;
-	KeyAgreementTransport(RecordReaderFactory recordReaderFactory,
+	KeyAgreementTransport(KeyAgreementConnection kac)
 			RecordWriterFactory recordWriterFactory, KeyAgreementConnection kac)
 			throws IOException {
 		this.kac = kac;
-		InputStream in = kac.getConnection().getReader().getInputStream();
+		in = kac.getConnection().getReader().getInputStream();
-		reader = recordReaderFactory.createRecordReader(in);
+		out = kac.getConnection().getWriter().getOutputStream();
 		OutputStream out = kac.getConnection().getWriter().getOutputStream();
 		writer = recordWriterFactory.createRecordWriter(out);
 	}
 	public DuplexTransportConnection getConnection() {
@@ -78,8 +74,9 @@ class KeyAgreementTransport {
 		tryToClose(exception);
 	}
-	private void tryToClose(boolean exception) {
+	public void tryToClose(boolean exception) {
 		try {
 			LOG.info("Closing connection");
 			kac.getConnection().getReader().dispose(exception, true);
 			kac.getConnection().getWriter().dispose(exception);
 		} catch (IOException e) {
@@ -88,27 +85,59 @@ class KeyAgreementTransport {
 	}
 	private void writeRecord(byte type, byte[] payload) throws IOException {
-		writer.writeRecord(new Record(PROTOCOL_VERSION, type, payload));
+		byte[] recordHeader = new byte[RECORD_HEADER_LENGTH];
-		writer.flush();
+		recordHeader[0] = PROTOCOL_VERSION;
 		recordHeader[1] = type;
 		ByteUtils.writeUint16(payload.length, recordHeader,
 				RECORD_HEADER_PAYLOAD_LENGTH_OFFSET);
 		out.write(recordHeader);
 		out.write(payload);
 		out.flush();
 	}
 	private byte[] readRecord(byte expectedType) throws AbortException {
 		while (true) {
 			byte[] header = readHeader();
 			byte version = header[0], type = header[1];
 			int len = ByteUtils.readUint16(header,
 					RECORD_HEADER_PAYLOAD_LENGTH_OFFSET);
 			// Reject unrecognised protocol version
 			if (version != PROTOCOL_VERSION) throw new AbortException(false);
 			if (type == ABORT) throw new AbortException(true);
 			if (type == expectedType) {
 				try {
 					return readData(len);
 				} catch (IOException e) {
 					throw new AbortException(e);
 				}
 			}
 			// Reject recognised but unexpected record type
 			if (type == KEY || type == CONFIRM) throw new AbortException(false);
 			// Skip unrecognised record type
 			try {
-				Record record = reader.readRecord();
+				readData(len);
 				// Reject unrecognised protocol version
 				if (record.getProtocolVersion() != PROTOCOL_VERSION)
 					throw new AbortException(false);
 				byte type = record.getRecordType();
 				if (type == ABORT) throw new AbortException(true);
 				if (type == expectedType) return record.getPayload();
 				// Reject recognised but unexpected record type
 				if (type == KEY || type == CONFIRM)
 					throw new AbortException(false);
 				// Skip unrecognised record type
 			} catch (IOException e) {
 				throw new AbortException(e);
 			}
 		}
 	}
 	private byte[] readHeader() throws AbortException {
 		try {
 			return readData(RECORD_HEADER_LENGTH);
 		} catch (IOException e) {
 			throw new AbortException(e);
 		}
 	}
 	private byte[] readData(int len) throws IOException {
 		byte[] data = new byte[len];
 		int offset = 0;
 		while (offset < data.length) {
 			int read = in.read(data, offset, data.length - offset);
 			if (read == -1) throw new EOFException();
 			offset += read;
 		}
 		return data;
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionLimiter.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionLimiter.java
@@ -1,47 +0,0 @@
 package org.briarproject.bramble.plugin.bluetooth;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
@NotNullByDefault
 interface BluetoothConnectionLimiter {
 	/**
 	 * Informs the limiter that key agreement has started.
 	 */
 	void keyAgreementStarted();
 	/**
 	 * Informs the limiter that key agreement has ended.
 	 */
 	void keyAgreementEnded();
 	/**
 	 * Returns true if a contact connection can be opened. This method does not
 	 * need to be called for key agreement connections.
 	 */
 	boolean canOpenContactConnection();
 	/**
 	 * Informs the limiter that a contact connection has been opened. The
 	 * limiter may close the new connection if key agreement is in progress.
 	 * <p/>
 	 * Returns false if the limiter has closed the new connection.
 	 */
 	boolean contactConnectionOpened(DuplexTransportConnection conn);
 	/**
 	 * Informs the limiter that a key agreement connection has been opened.
 	 */
 	void keyAgreementConnectionOpened(DuplexTransportConnection conn);
 	/**
 	 * Informs the limiter that the given connection has been closed.
 	 */
 	void connectionClosed(DuplexTransportConnection conn);
 	/**
 	 * Informs the limiter that all connections have been closed.
 	 */
 	void allConnectionsClosed();
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionLimiterImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionLimiterImpl.java
@@ -1,115 +0,0 @@
 package org.briarproject.bramble.plugin.bluetooth;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.logging.Logger;
 import javax.annotation.concurrent.ThreadSafe;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@NotNullByDefault
@ThreadSafe
 class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	private static final Logger LOG =
 			Logger.getLogger(BluetoothConnectionLimiterImpl.class.getName());
 	private final Object lock = new Object();
 	// The following are locking: lock
 	private final LinkedList<DuplexTransportConnection> connections =
 			new LinkedList<>();
 	private boolean keyAgreementInProgress = false;
 	@Override
 	public void keyAgreementStarted() {
 		List<DuplexTransportConnection> close;
 		synchronized (lock) {
 			keyAgreementInProgress = true;
 			close = new ArrayList<>(connections);
 			connections.clear();
 		}
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("Key agreement started, closing " + close.size() +
 					" connections");
 		}
 		for (DuplexTransportConnection conn : close) tryToClose(conn);
 	}
 	@Override
 	public void keyAgreementEnded() {
 		synchronized (lock) {
 			keyAgreementInProgress = false;
 		}
 		LOG.info("Key agreement ended");
 	}
 	@Override
 	public boolean canOpenContactConnection() {
 		synchronized (lock) {
 			if (keyAgreementInProgress) {
 				LOG.info("Can't open contact connection during key agreement");
 				return false;
 			} else {
 				LOG.info("Can open contact connection");
 				return true;
 			}
 		}
 	}
 	@Override
 	public boolean contactConnectionOpened(DuplexTransportConnection conn) {
 		boolean accept = true;
 		synchronized (lock) {
 			if (keyAgreementInProgress) {
 				LOG.info("Refusing contact connection during key agreement");
 				accept = false;
 			} else {
 				LOG.info("Accepting contact connection");
 				connections.add(conn);
 			}
 		}
 		if (!accept) tryToClose(conn);
 		return accept;
 	}
 	@Override
 	public void keyAgreementConnectionOpened(DuplexTransportConnection conn) {
 		synchronized (lock) {
 			LOG.info("Accepting key agreement connection");
 			connections.add(conn);
 		}
 	}
 	private void tryToClose(DuplexTransportConnection conn) {
 		try {
 			conn.getWriter().dispose(false);
 			conn.getReader().dispose(false, false);
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 		}
 	}
 	@Override
 	public void connectionClosed(DuplexTransportConnection conn) {
 		synchronized (lock) {
 			connections.remove(conn);
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connection closed, " + connections.size() + " open");
 		}
 	}
 	@Override
 	public void allConnectionsClosed() {
 		synchronized (lock) {
 			connections.clear();
 			LOG.info("All connections closed");
 		}
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothPlugin.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothPlugin.java
@@ -7,8 +7,6 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -53,8 +51,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(BluetoothPlugin.class.getName());
 	final BluetoothConnectionLimiter connectionLimiter;
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
 	private final Backoff backoff;
@@ -95,10 +91,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection connectTo(String address, String uuid)
 			throws IOException;
-	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
+	BluetoothPlugin(Executor ioExecutor, SecureRandom secureRandom,
 			Executor ioExecutor, SecureRandom secureRandom,
 			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
 		this.connectionLimiter = connectionLimiter;
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
 		this.backoff = backoff;
@@ -116,7 +110,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	void onAdapterDisabled() {
 		LOG.info("Bluetooth disabled");
 		tryToClose(socket);
 		connectionLimiter.allConnectionsClosed();
 		callback.transportDisabled();
 	}
@@ -220,8 +213,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 				return;
 			}
 			backoff.reset();
-			if (connectionLimiter.contactConnectionOpened(conn))
+			callback.incomingConnectionCreated(conn);
 				callback.incomingConnectionCreated(conn);
 			if (!running) return;
 		}
 	}
@@ -265,12 +257,10 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			if (StringUtils.isNullOrEmpty(uuid)) continue;
 			ioExecutor.execute(() -> {
 				if (!isRunning() || !shouldAllowContactConnections()) return;
 				if (!connectionLimiter.canOpenContactConnection()) return;
 				DuplexTransportConnection conn = connect(address, uuid);
 				if (conn != null) {
 					backoff.reset();
-					if (connectionLimiter.contactConnectionOpened(conn))
+					callback.outgoingConnectionCreated(c, conn);
 						callback.outgoingConnectionCreated(c, conn);
 				}
 			});
 		}
@@ -310,16 +300,12 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public DuplexTransportConnection createConnection(ContactId c) {
 		if (!isRunning() || !shouldAllowContactConnections()) return null;
 		if (!connectionLimiter.canOpenContactConnection()) return null;
 		TransportProperties p = callback.getRemoteProperties(c);
 		String address = p.get(PROP_ADDRESS);
 		if (StringUtils.isNullOrEmpty(address)) return null;
 		String uuid = p.get(PROP_UUID);
 		if (StringUtils.isNullOrEmpty(uuid)) return null;
-		DuplexTransportConnection conn = connect(address, uuid);
+		return connect(address, uuid);
 		if (conn == null) return null;
 		// TODO: Why don't we reset the backoff here?
 		return connectionLimiter.contactConnectionOpened(conn) ? conn : null;
 	}
 	@Override
@@ -369,9 +355,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO))
 			LOG.info("Connecting to key agreement UUID " + uuid);
-		DuplexTransportConnection conn = connect(address, uuid);
+		return connect(address, uuid);
 		if (conn != null) connectionLimiter.keyAgreementConnectionOpened(conn);
 		return conn;
 	}
 	private String parseAddress(BdfList descriptor) throws FormatException {
@@ -392,10 +376,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
 			if (s.getNamespace().equals(ID.getString()))
 				ioExecutor.execute(this::onSettingsUpdated);
 		} else if (e instanceof KeyAgreementListeningEvent) {
 			ioExecutor.execute(connectionLimiter::keyAgreementStarted);
 		} else if (e instanceof KeyAgreementStoppedListeningEvent) {
 			ioExecutor.execute(connectionLimiter::keyAgreementEnded);
 		}
 	}
@@ -428,7 +408,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		public KeyAgreementConnection accept() throws IOException {
 			DuplexTransportConnection conn = acceptConnection(ss);
 			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
 			connectionLimiter.keyAgreementConnectionOpened(conn);
 			return new KeyAgreementConnection(conn, ID);
 		}
--- a/bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java
@@ -241,11 +241,10 @@ class LanTcpPlugin extends TcpPlugin {
 			}
 			return null;
 		}
 		Socket s = new Socket();
 		try {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
 			Socket s = createSocket();
 			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 			s.connect(remote);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
--- a/bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java
@@ -1,6 +1,5 @@
 package org.briarproject.bramble.plugin.tcp;
 import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
@@ -48,7 +47,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	private static final Logger LOG =
 			Logger.getLogger(TcpPlugin.class.getName());
-	protected final Executor ioExecutor, bindExecutor;
+	protected final Executor ioExecutor;
 	protected final Backoff backoff;
 	protected final DuplexPluginCallback callback;
 	protected final int maxLatency, maxIdleTime, socketTimeout;
@@ -91,8 +90,6 @@ abstract class TcpPlugin implements DuplexPlugin {
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
 		// Don't execute more than one bind operation at a time
 		bindExecutor = new PoliteExecutor("TcpPlugin", ioExecutor, 1);
 	}
 	@Override
@@ -113,9 +110,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 	protected void bind() {
-		bindExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			if (!running) return;
 			if (socket != null && !socket.isClosed()) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -247,11 +243,10 @@ abstract class TcpPlugin implements DuplexPlugin {
 				}
 				continue;
 			}
 			Socket s = new Socket();
 			try {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
 				Socket s = createSocket();
 				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 				s.connect(remote);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
@@ -266,10 +261,6 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return null;
 	}
 	protected Socket createSocket() throws IOException {
 		return new Socket();
 	}
 	@Nullable
 	InetSocketAddress parseSocketAddress(String ipPort) {
 		if (StringUtils.isNullOrEmpty(ipPort)) return null;
--- a/bramble-core/src/main/java/org/briarproject/bramble/properties/PropertiesModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/properties/PropertiesModule.java
@@ -7,7 +7,6 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -16,8 +15,6 @@ import dagger.Module;
 import dagger.Provides;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.CLIENT_ID;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.MAJOR_VERSION;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.MINOR_VERSION;
@Module
 public class PropertiesModule {
@@ -36,8 +33,7 @@ public class PropertiesModule {
 			Clock clock) {
 		TransportPropertyValidator validator = new TransportPropertyValidator(
 				clientHelper, metadataEncoder, clock);
-		validationManager.registerMessageValidator(CLIENT_ID, MAJOR_VERSION,
+		validationManager.registerMessageValidator(CLIENT_ID, validator);
 				validator);
 		return validator;
 	}
@@ -46,14 +42,12 @@ public class PropertiesModule {
 	TransportPropertyManager getTransportPropertyManager(
 			LifecycleManager lifecycleManager,
 			ValidationManager validationManager, ContactManager contactManager,
 			ClientVersioningManager clientVersioningManager,
 			TransportPropertyManagerImpl transportPropertyManager) {
 		lifecycleManager.registerClient(transportPropertyManager);
-		validationManager.registerIncomingMessageHook(CLIENT_ID, MAJOR_VERSION,
+		validationManager.registerIncomingMessageHook(CLIENT_ID,
 				transportPropertyManager);
-		contactManager.registerContactHook(transportPropertyManager);
+		contactManager.registerAddContactHook(transportPropertyManager);
-		clientVersioningManager.registerClient(CLIENT_ID, MAJOR_VERSION,
+		contactManager.registerRemoveContactHook(transportPropertyManager);
 				MINOR_VERSION, transportPropertyManager);
 		return transportPropertyManager;
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java
@@ -5,7 +5,8 @@ import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.client.ContactGroupFactory;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.ContactManager.ContactHook;
+import org.briarproject.bramble.api.contact.ContactManager.AddContactHook;
 import org.briarproject.bramble.api.contact.ContactManager.RemoveContactHook;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.MetadataParser;
@@ -19,15 +20,12 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.sync.Client;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.Group.Visibility;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
 import java.util.HashMap;
 import java.util.Map;
@@ -37,14 +35,15 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@Immutable
@NotNullByDefault
 class TransportPropertyManagerImpl implements TransportPropertyManager,
-		Client, ContactHook, ClientVersioningHook, IncomingMessageHook {
+		Client, AddContactHook, RemoveContactHook, IncomingMessageHook {
 	private final DatabaseComponent db;
 	private final ClientHelper clientHelper;
 	private final ClientVersioningManager clientVersioningManager;
 	private final MetadataParser metadataParser;
 	private final ContactGroupFactory contactGroupFactory;
 	private final Clock clock;
@@ -52,25 +51,22 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Inject
 	TransportPropertyManagerImpl(DatabaseComponent db,
-			ClientHelper clientHelper,
+			ClientHelper clientHelper, MetadataParser metadataParser,
 			ClientVersioningManager clientVersioningManager,
 			MetadataParser metadataParser,
 			ContactGroupFactory contactGroupFactory, Clock clock) {
 		this.db = db;
 		this.clientHelper = clientHelper;
 		this.clientVersioningManager = clientVersioningManager;
 		this.metadataParser = metadataParser;
 		this.contactGroupFactory = contactGroupFactory;
 		this.clock = clock;
 		localGroup = contactGroupFactory.createLocalGroup(CLIENT_ID,
-				MAJOR_VERSION);
+				CLIENT_VERSION);
 	}
 	@Override
 	public void createLocalState(Transaction txn) throws DbException {
 		if (db.containsGroup(txn, localGroup.getId())) return;
 		db.addGroup(txn, localGroup);
-		// Set things up for any pre-existing contacts
+		// Ensure we've set things up for any pre-existing contacts
 		for (Contact c : db.getContacts(txn)) addingContact(txn, c);
 	}
@@ -78,11 +74,11 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public void addingContact(Transaction txn, Contact c) throws DbException {
 		// Create a group to share with the contact
 		Group g = getContactGroup(c);
 		// Return if we've already set things up for this contact
 		if (db.containsGroup(txn, g.getId())) return;
 		// Store the group and share it with the contact
 		db.addGroup(txn, g);
-		// Apply the client's visibility to the contact group
+		db.setGroupVisibility(txn, c.getId(), g.getId(), SHARED);
 		Visibility client = clientVersioningManager.getClientVisibility(txn,
 				c.getId(), CLIENT_ID, MAJOR_VERSION);
 		db.setGroupVisibility(txn, c.getId(), g.getId(), client);
 		// Copy the latest local properties into the group
 		Map<TransportId, TransportProperties> local = getLocalProperties(txn);
 		for (Entry<TransportId, TransportProperties> e : local.entrySet()) {
@@ -96,14 +92,6 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		db.removeGroup(txn, getContactGroup(c));
 	}
 	@Override
 	public void onClientVisibilityChanging(Transaction txn, Contact c,
 			Visibility v) throws DbException {
 		// Apply the client's visibility to the contact group
 		Group g = getContactGroup(c);
 		db.setGroupVisibility(txn, c.getId(), g.getId(), v);
 	}
 	@Override
 	public boolean incomingMessage(Transaction txn, Message m, Metadata meta)
 			throws DbException, InvalidMessageException {
@@ -302,7 +290,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	private Group getContactGroup(Contact c) {
 		return contactGroupFactory.createContactGroup(CLIENT_ID,
-				MAJOR_VERSION, c);
+				CLIENT_VERSION, c);
 	}
 	private void storeMessage(Transaction txn, GroupId g, TransportId t,
@@ -360,7 +348,10 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			throws FormatException {
 		// Transport ID, version, properties
 		BdfDictionary dictionary = message.getDictionary(2);
-		return clientHelper.parseAndValidateTransportProperties(dictionary);
+		TransportProperties p = new TransportProperties();
 		for (String key : dictionary.keySet())
 			p.put(key, dictionary.getString(key));
 		return p;
 	}
 	private static class LatestUpdate {
--- a/bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyValidator.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyValidator.java
@@ -15,6 +15,8 @@ import org.briarproject.bramble.api.system.Clock;
 import javax.annotation.concurrent.Immutable;
 import static org.briarproject.bramble.api.plugin.TransportId.MAX_TRANSPORT_ID_LENGTH;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTIES_PER_TRANSPORT;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTY_LENGTH;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
@@ -40,7 +42,12 @@ class TransportPropertyValidator extends BdfMessageValidator {
 		if (version < 0) throw new FormatException();
 		// Properties
 		BdfDictionary dictionary = body.getDictionary(2);
-		clientHelper.parseAndValidateTransportProperties(dictionary);
+		checkSize(dictionary, 0, MAX_PROPERTIES_PER_TRANSPORT);
 		for (String key : dictionary.keySet()) {
 			checkLength(key, 0, MAX_PROPERTY_LENGTH);
 			String value = dictionary.getString(key);
 			checkLength(value, 0, MAX_PROPERTY_LENGTH);
 		}
 		// Return the metadata
 		BdfDictionary meta = new BdfDictionary();
 		meta.put("transportId", transportId);
--- a/bramble-core/src/main/java/org/briarproject/bramble/record/RecordModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/record/RecordModule.java
@@ -1,21 +0,0 @@
 package org.briarproject.bramble.record;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import dagger.Module;
 import dagger.Provides;
@Module
 public class RecordModule {
 	@Provides
 	RecordReaderFactory provideRecordReaderFactory() {
 		return new RecordReaderFactoryImpl();
 	}
 	@Provides
 	RecordWriterFactory provideRecordWriterFactory() {
 		return new RecordWriterFactoryImpl();
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/record/RecordReaderFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/record/RecordReaderFactoryImpl.java
@@ -1,14 +0,0 @@
 package org.briarproject.bramble.record;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import java.io.InputStream;
 class RecordReaderFactoryImpl implements RecordReaderFactory {
 	@Override
 	public RecordReader createRecordReader(InputStream in) {
 		return new RecordReaderImpl(in);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/record/RecordReaderImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/record/RecordReaderImpl.java
@@ -1,46 +0,0 @@
 package org.briarproject.bramble.record;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.Record;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.util.ByteUtils;
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import javax.annotation.concurrent.NotThreadSafe;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 import static org.briarproject.bramble.api.record.Record.RECORD_HEADER_BYTES;
@NotThreadSafe
@NotNullByDefault
 class RecordReaderImpl implements RecordReader {
 	private final DataInputStream in;
 	private final byte[] header = new byte[RECORD_HEADER_BYTES];
 	RecordReaderImpl(InputStream in) {
 		this.in = new DataInputStream(in);
 	}
 	@Override
 	public Record readRecord() throws IOException {
 		in.readFully(header);
 		byte protocolVersion = header[0];
 		byte recordType = header[1];
 		int payloadLength = ByteUtils.readUint16(header, 2);
 		if (payloadLength < 0 || payloadLength > MAX_RECORD_PAYLOAD_BYTES)
 			throw new FormatException();
 		byte[] payload = new byte[payloadLength];
 		in.readFully(payload);
 		return new Record(protocolVersion, recordType, payload);
 	}
 	@Override
 	public void close() throws IOException {
 		in.close();
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/record/RecordWriterFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/record/RecordWriterFactoryImpl.java
@@ -1,14 +0,0 @@
 package org.briarproject.bramble.record;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.OutputStream;
 class RecordWriterFactoryImpl implements RecordWriterFactory {
 	@Override
 	public RecordWriter createRecordWriter(OutputStream out) {
 		return new RecordWriterImpl(out);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/record/RecordWriterImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/record/RecordWriterImpl.java
@@ -1,45 +0,0 @@
 package org.briarproject.bramble.record;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.Record;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.util.ByteUtils;
 import java.io.IOException;
 import java.io.OutputStream;
 import javax.annotation.concurrent.NotThreadSafe;
 import static org.briarproject.bramble.api.record.Record.RECORD_HEADER_BYTES;
@NotThreadSafe
@NotNullByDefault
 class RecordWriterImpl implements RecordWriter {
 	private final OutputStream out;
 	private final byte[] header = new byte[RECORD_HEADER_BYTES];
 	RecordWriterImpl(OutputStream out) {
 		this.out = out;
 	}
 	@Override
 	public void writeRecord(Record r) throws IOException {
 		byte[] payload = r.getPayload();
 		header[0] = r.getProtocolVersion();
 		header[1] = r.getRecordType();
 		ByteUtils.writeUint16(payload.length, header, 2);
 		out.write(header);
 		out.write(payload);
 	}
 	@Override
 	public void flush() throws IOException {
 		out.flush();
 	}
 	@Override
 	public void close() throws IOException {
 		out.close();
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java
@@ -14,8 +14,8 @@ import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.RecordWriter;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
 import org.briarproject.bramble.api.sync.event.MessageRequestedEvent;
@@ -39,8 +39,8 @@ import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 /**
 * An outgoing {@link SyncSession} suitable for duplex transports. The session
@@ -67,7 +67,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private final Clock clock;
 	private final ContactId contactId;
 	private final int maxLatency, maxIdleTime;
-	private final SyncRecordWriter recordWriter;
+	private final RecordWriter recordWriter;
 	private final BlockingQueue<ThrowingRunnable<IOException>> writerTasks;
 	private final AtomicBoolean generateAckQueued = new AtomicBoolean(false);
@@ -81,7 +81,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	DuplexOutgoingSession(DatabaseComponent db, Executor dbExecutor,
 			EventBus eventBus, Clock clock, ContactId contactId, int maxLatency,
-			int maxIdleTime, SyncRecordWriter recordWriter) {
+			int maxIdleTime, RecordWriter recordWriter) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
@@ -273,7 +273,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 				Transaction txn = db.startTransaction(false);
 				try {
 					b = db.generateRequestedBatch(txn, contactId,
-							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
+							MAX_RECORD_PAYLOAD_LENGTH, maxLatency);
 					setNextSendTime(db.getNextSendTime(txn, contactId));
 					db.commitTransaction(txn);
 				} finally {
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/GroupFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/GroupFactoryImpl.java
@@ -12,17 +12,14 @@ import org.briarproject.bramble.util.StringUtils;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import static org.briarproject.bramble.api.sync.Group.FORMAT_VERSION;
 import static org.briarproject.bramble.api.sync.GroupId.LABEL;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
@Immutable
@NotNullByDefault
 class GroupFactoryImpl implements GroupFactory {
 	private static final byte[] FORMAT_VERSION_BYTES =
 			new byte[] {FORMAT_VERSION};
 	private final CryptoComponent crypto;
 	@Inject
@@ -31,12 +28,12 @@ class GroupFactoryImpl implements GroupFactory {
 	}
 	@Override
-	public Group createGroup(ClientId c, int majorVersion, byte[] descriptor) {
+	public Group createGroup(ClientId c, int clientVersion, byte[] descriptor) {
-		byte[] majorVersionBytes = new byte[INT_32_BYTES];
+		byte[] clientVersionBytes = new byte[INT_32_BYTES];
-		ByteUtils.writeUint32(majorVersion, majorVersionBytes, 0);
+		ByteUtils.writeUint32(clientVersion, clientVersionBytes, 0);
-		byte[] hash = crypto.hash(LABEL, FORMAT_VERSION_BYTES,
+		byte[] hash = crypto.hash(LABEL, new byte[] {PROTOCOL_VERSION},
-				StringUtils.toUtf8(c.getString()), majorVersionBytes,
+				StringUtils.toUtf8(c.getString()), clientVersionBytes,
 				descriptor);
-		return new Group(new GroupId(hash), c, majorVersion, descriptor);
+		return new Group(new GroupId(hash), c, descriptor);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java
@@ -16,8 +16,8 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.RecordReader;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
 import org.briarproject.bramble.api.sync.SyncSession;
 import java.io.IOException;
@@ -43,13 +43,13 @@ class IncomingSession implements SyncSession, EventListener {
 	private final Executor dbExecutor;
 	private final EventBus eventBus;
 	private final ContactId contactId;
-	private final SyncRecordReader recordReader;
+	private final RecordReader recordReader;
 	private volatile boolean interrupted = false;
 	IncomingSession(DatabaseComponent db, Executor dbExecutor,
 			EventBus eventBus, ContactId contactId,
-			SyncRecordReader recordReader) {
+			RecordReader recordReader) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/MessageFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/MessageFactoryImpl.java
@@ -12,21 +12,15 @@ import org.briarproject.bramble.util.ByteUtils;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
-import static org.briarproject.bramble.api.sync.Message.FORMAT_VERSION;
+import static org.briarproject.bramble.api.sync.MessageId.LABEL;
 import static org.briarproject.bramble.api.sync.MessageId.BLOCK_LABEL;
 import static org.briarproject.bramble.api.sync.MessageId.ID_LABEL;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
-import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
+import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
@Immutable
@NotNullByDefault
 class MessageFactoryImpl implements MessageFactory {
 	private static final byte[] FORMAT_VERSION_BYTES =
 			new byte[] {FORMAT_VERSION};
 	private final CryptoComponent crypto;
 	@Inject
@@ -38,7 +32,11 @@ class MessageFactoryImpl implements MessageFactory {
 	public Message createMessage(GroupId g, long timestamp, byte[] body) {
 		if (body.length > MAX_MESSAGE_BODY_LENGTH)
 			throw new IllegalArgumentException();
-		MessageId id = getMessageId(g, timestamp, body);
+		byte[] timeBytes = new byte[ByteUtils.INT_64_BYTES];
 		ByteUtils.writeUint64(timestamp, timeBytes, 0);
 		byte[] hash = crypto.hash(LABEL, new byte[] {PROTOCOL_VERSION},
 				g.getBytes(), timeBytes, body);
 		MessageId id = new MessageId(hash);
 		byte[] raw = new byte[MESSAGE_HEADER_LENGTH + body.length];
 		System.arraycopy(g.getBytes(), 0, raw, 0, UniqueId.LENGTH);
 		ByteUtils.writeUint64(timestamp, raw, UniqueId.LENGTH);
@@ -46,38 +44,10 @@ class MessageFactoryImpl implements MessageFactory {
 		return new Message(id, g, timestamp, raw);
 	}
 	private MessageId getMessageId(GroupId g, long timestamp, byte[] body) {
 		// There's only one block, so the root hash is the hash of the block
 		byte[] rootHash = crypto.hash(BLOCK_LABEL, FORMAT_VERSION_BYTES, body);
 		byte[] timeBytes = new byte[INT_64_BYTES];
 		ByteUtils.writeUint64(timestamp, timeBytes, 0);
 		byte[] idHash = crypto.hash(ID_LABEL, FORMAT_VERSION_BYTES,
 				g.getBytes(), timeBytes, rootHash);
 		return new MessageId(idHash);
 	}
 	@Override
 	public Message createMessage(byte[] raw) {
 		if (raw.length < MESSAGE_HEADER_LENGTH)
 			throw new IllegalArgumentException();
 		if (raw.length > MAX_MESSAGE_LENGTH)
 			throw new IllegalArgumentException();
 		byte[] groupId = new byte[UniqueId.LENGTH];
 		System.arraycopy(raw, 0, groupId, 0, UniqueId.LENGTH);
 		GroupId g = new GroupId(groupId);
 		long timestamp = ByteUtils.readUint64(raw, UniqueId.LENGTH);
 		byte[] body = new byte[raw.length - MESSAGE_HEADER_LENGTH];
 		System.arraycopy(raw, MESSAGE_HEADER_LENGTH, body, 0, body.length);
 		MessageId id = getMessageId(g, timestamp, body);
 		return new Message(id, g, timestamp, raw);
 	}
 	@Override
 	public Message createMessage(MessageId m, byte[] raw) {
 		if (raw.length < MESSAGE_HEADER_LENGTH)
 			throw new IllegalArgumentException();
 		if (raw.length > MAX_MESSAGE_LENGTH)
 			throw new IllegalArgumentException();
 		byte[] groupId = new byte[UniqueId.LENGTH];
 		System.arraycopy(raw, 0, groupId, 0, UniqueId.LENGTH);
 		long timestamp = ByteUtils.readUint64(raw, UniqueId.LENGTH);
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/RecordReaderFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/RecordReaderFactoryImpl.java
@@ -0,0 +1,28 @@
 package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.RecordReader;
 import org.briarproject.bramble.api.sync.RecordReaderFactory;
 import java.io.InputStream;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
@Immutable
@NotNullByDefault
 class RecordReaderFactoryImpl implements RecordReaderFactory {
 	private final MessageFactory messageFactory;
 	@Inject
 	RecordReaderFactoryImpl(MessageFactory messageFactory) {
 		this.messageFactory = messageFactory;
 	}
 	@Override
 	public RecordReader createRecordReader(InputStream in) {
 		return new RecordReaderImpl(messageFactory, in);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordReaderImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordReaderImpl.java
@@ -3,56 +3,82 @@ package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.Record;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.RecordReader;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
 import org.briarproject.bramble.util.ByteUtils;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 import static org.briarproject.bramble.api.sync.RecordTypes.ACK;
 import static org.briarproject.bramble.api.sync.RecordTypes.MESSAGE;
 import static org.briarproject.bramble.api.sync.RecordTypes.OFFER;
 import static org.briarproject.bramble.api.sync.RecordTypes.REQUEST;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.sync.SyncConstants.RECORD_HEADER_LENGTH;
@NotThreadSafe
@NotNullByDefault
-class SyncRecordReaderImpl implements SyncRecordReader {
+class RecordReaderImpl implements RecordReader {
 	private enum State {BUFFER_EMPTY, BUFFER_FULL, EOF}
 	private final MessageFactory messageFactory;
-	private final RecordReader reader;
+	private final InputStream in;
 	private final byte[] header, payload;
-	@Nullable
+	private State state = State.BUFFER_EMPTY;
-	private Record nextRecord = null;
+	private int payloadLength = 0;
 	private boolean eof = false;
-	SyncRecordReaderImpl(MessageFactory messageFactory, RecordReader reader) {
+	RecordReaderImpl(MessageFactory messageFactory, InputStream in) {
 		this.messageFactory = messageFactory;
-		this.reader = reader;
+		this.in = in;
 		header = new byte[RECORD_HEADER_LENGTH];
 		payload = new byte[MAX_RECORD_PAYLOAD_LENGTH];
 	}
 	private void readRecord() throws IOException {
-		assert nextRecord == null;
+		if (state != State.BUFFER_EMPTY) throw new IllegalStateException();
 		while (true) {
-			nextRecord = reader.readRecord();
+			// Read the header
 			int offset = 0;
 			while (offset < RECORD_HEADER_LENGTH) {
 				int read =
 						in.read(header, offset, RECORD_HEADER_LENGTH - offset);
 				if (read == -1) {
 					if (offset > 0) throw new FormatException();
 					state = State.EOF;
 					return;
 				}
 				offset += read;
 			}
 			byte version = header[0], type = header[1];
 			payloadLength = ByteUtils.readUint16(header, 2);
 			// Check the protocol version
 			byte version = nextRecord.getProtocolVersion();
 			if (version != PROTOCOL_VERSION) throw new FormatException();
-			byte type = nextRecord.getRecordType();
+			// Check the payload length
 			if (payloadLength > MAX_RECORD_PAYLOAD_LENGTH)
 				throw new FormatException();
 			// Read the payload
 			offset = 0;
 			while (offset < payloadLength) {
 				int read = in.read(payload, offset, payloadLength - offset);
 				if (read == -1) throw new FormatException();
 				offset += read;
 			}
 			state = State.BUFFER_FULL;
 			// Return if this is a known record type, otherwise continue
 			if (type == ACK || type == MESSAGE || type == OFFER ||
 					type == REQUEST) {
@@ -61,11 +87,6 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 		}
 	}
 	private byte getNextRecordType() {
 		assert nextRecord != null;
 		return nextRecord.getRecordType();
 	}
 	/**
 	 * Returns true if there's another record available or false if we've
 	 * reached the end of the input stream.
@@ -76,21 +97,14 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 	 */
 	@Override
 	public boolean eof() throws IOException {
-		if (nextRecord != null) return false;
+		if (state == State.BUFFER_EMPTY) readRecord();
-		if (eof) return true;
+		if (state == State.BUFFER_EMPTY) throw new IllegalStateException();
-		try {
+		return state == State.EOF;
 			readRecord();
 			return false;
 		} catch (EOFException e) {
 			nextRecord = null;
 			eof = true;
 			return true;
 		}
 	}
 	@Override
 	public boolean hasAck() throws IOException {
-		return !eof() && getNextRecordType() == ACK;
+		return !eof() && header[1] == ACK;
 	}
 	@Override
@@ -100,41 +114,45 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 	}
 	private List<MessageId> readMessageIds() throws IOException {
-		assert nextRecord != null;
+		if (payloadLength == 0) throw new FormatException();
-		byte[] payload = nextRecord.getPayload();
+		if (payloadLength % UniqueId.LENGTH != 0) throw new FormatException();
-		if (payload.length == 0) throw new FormatException();
+		List<MessageId> ids = new ArrayList<>();
-		if (payload.length % UniqueId.LENGTH != 0) throw new FormatException();
+		for (int off = 0; off < payloadLength; off += UniqueId.LENGTH) {
 		List<MessageId> ids = new ArrayList<>(payload.length / UniqueId.LENGTH);
 		for (int off = 0; off < payload.length; off += UniqueId.LENGTH) {
 			byte[] id = new byte[UniqueId.LENGTH];
 			System.arraycopy(payload, off, id, 0, UniqueId.LENGTH);
 			ids.add(new MessageId(id));
 		}
-		nextRecord = null;
+		state = State.BUFFER_EMPTY;
 		return ids;
 	}
 	@Override
 	public boolean hasMessage() throws IOException {
-		return !eof() && getNextRecordType() == MESSAGE;
+		return !eof() && header[1] == MESSAGE;
 	}
 	@Override
 	public Message readMessage() throws IOException {
 		if (!hasMessage()) throw new FormatException();
-		assert nextRecord != null;
+		if (payloadLength <= MESSAGE_HEADER_LENGTH) throw new FormatException();
-		byte[] payload = nextRecord.getPayload();
+		// Group ID
-		if (payload.length < MESSAGE_HEADER_LENGTH) throw new FormatException();
+		byte[] id = new byte[UniqueId.LENGTH];
-		// Validate timestamp
+		System.arraycopy(payload, 0, id, 0, UniqueId.LENGTH);
 		GroupId groupId = new GroupId(id);
 		// Timestamp
 		long timestamp = ByteUtils.readUint64(payload, UniqueId.LENGTH);
 		if (timestamp < 0) throw new FormatException();
-		nextRecord = null;
+		// Body
-		return messageFactory.createMessage(payload);
+		byte[] body = new byte[payloadLength - MESSAGE_HEADER_LENGTH];
 		System.arraycopy(payload, MESSAGE_HEADER_LENGTH, body, 0,
 				payloadLength - MESSAGE_HEADER_LENGTH);
 		state = State.BUFFER_EMPTY;
 		return messageFactory.createMessage(groupId, timestamp, body);
 	}
 	@Override
 	public boolean hasOffer() throws IOException {
-		return !eof() && getNextRecordType() == OFFER;
+		return !eof() && header[1] == OFFER;
 	}
 	@Override
@@ -145,7 +163,7 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 	@Override
 	public boolean hasRequest() throws IOException {
-		return !eof() && getNextRecordType() == REQUEST;
+		return !eof() && header[1] == REQUEST;
 	}
 	@Override
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/RecordWriterFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/RecordWriterFactoryImpl.java
@@ -0,0 +1,16 @@
 package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.RecordWriter;
 import org.briarproject.bramble.api.sync.RecordWriterFactory;
 import java.io.OutputStream;
@NotNullByDefault
 class RecordWriterFactoryImpl implements RecordWriterFactory {
 	@Override
 	public RecordWriter createRecordWriter(OutputStream out) {
 		return new RecordWriterImpl(out);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordWriterImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordWriterImpl.java
@@ -1,67 +1,81 @@
 package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.Record;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.RecordTypes;
 import org.briarproject.bramble.api.sync.RecordWriter;
 import org.briarproject.bramble.api.sync.Request;
-import org.briarproject.bramble.api.sync.SyncRecordWriter;
+import org.briarproject.bramble.util.ByteUtils;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import javax.annotation.concurrent.NotThreadSafe;
 import static org.briarproject.bramble.api.sync.RecordTypes.ACK;
 import static org.briarproject.bramble.api.sync.RecordTypes.MESSAGE;
 import static org.briarproject.bramble.api.sync.RecordTypes.OFFER;
 import static org.briarproject.bramble.api.sync.RecordTypes.REQUEST;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.RECORD_HEADER_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
@NotThreadSafe
@NotNullByDefault
-class SyncRecordWriterImpl implements SyncRecordWriter {
+class RecordWriterImpl implements RecordWriter {
-	private final RecordWriter writer;
+	private final OutputStream out;
-	private final ByteArrayOutputStream payload = new ByteArrayOutputStream();
+	private final byte[] header;
 	private final ByteArrayOutputStream payload;
-	SyncRecordWriterImpl(RecordWriter writer) {
+	RecordWriterImpl(OutputStream out) {
-		this.writer = writer;
+		this.out = out;
 		header = new byte[RECORD_HEADER_LENGTH];
 		header[0] = PROTOCOL_VERSION;
 		payload = new ByteArrayOutputStream(MAX_RECORD_PAYLOAD_LENGTH);
 	}
 	private void writeRecord(byte recordType) throws IOException {
-		writer.writeRecord(new Record(PROTOCOL_VERSION, recordType,
+		header[1] = recordType;
-				payload.toByteArray()));
+		ByteUtils.writeUint16(payload.size(), header, 2);
 		out.write(header);
 		payload.writeTo(out);
 		payload.reset();
 	}
 	@Override
 	public void writeAck(Ack a) throws IOException {
 		if (payload.size() != 0) throw new IllegalStateException();
 		for (MessageId m : a.getMessageIds()) payload.write(m.getBytes());
 		writeRecord(ACK);
 	}
 	@Override
 	public void writeMessage(byte[] raw) throws IOException {
-		writer.writeRecord(new Record(PROTOCOL_VERSION, MESSAGE, raw));
+		header[1] = RecordTypes.MESSAGE;
 		ByteUtils.writeUint16(raw.length, header, 2);
 		out.write(header);
 		out.write(raw);
 	}
 	@Override
 	public void writeOffer(Offer o) throws IOException {
 		if (payload.size() != 0) throw new IllegalStateException();
 		for (MessageId m : o.getMessageIds()) payload.write(m.getBytes());
 		writeRecord(OFFER);
 	}
 	@Override
 	public void writeRequest(Request r) throws IOException {
 		if (payload.size() != 0) throw new IllegalStateException();
 		for (MessageId m : r.getMessageIds()) payload.write(m.getBytes());
 		writeRecord(REQUEST);
 	}
 	@Override
 	public void flush() throws IOException {
-		writer.flush();
+		out.flush();
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java
@@ -13,7 +13,7 @@ import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
-import org.briarproject.bramble.api.sync.SyncRecordWriter;
+import org.briarproject.bramble.api.sync.RecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
 import java.io.IOException;
@@ -29,8 +29,8 @@ import javax.annotation.concurrent.ThreadSafe;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 /**
 * An outgoing {@link SyncSession} suitable for simplex transports. The session
@@ -51,7 +51,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	private final EventBus eventBus;
 	private final ContactId contactId;
 	private final int maxLatency;
-	private final SyncRecordWriter recordWriter;
+	private final RecordWriter recordWriter;
 	private final AtomicInteger outstandingQueries;
 	private final BlockingQueue<ThrowingRunnable<IOException>> writerTasks;
@@ -59,7 +59,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	SimplexOutgoingSession(DatabaseComponent db, Executor dbExecutor,
 			EventBus eventBus, ContactId contactId,
-			int maxLatency, SyncRecordWriter recordWriter) {
+			int maxLatency, RecordWriter recordWriter) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
@@ -171,7 +171,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 				Transaction txn = db.startTransaction(false);
 				try {
 					b = db.generateBatch(txn, contactId,
-							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
+							MAX_RECORD_PAYLOAD_LENGTH, maxLatency);
 					db.commitTransaction(txn);
 				} finally {
 					db.endTransaction(txn);
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncModule.java
@@ -9,8 +9,8 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.sync.GroupFactory;
 import org.briarproject.bramble.api.sync.MessageFactory;
-import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
+import org.briarproject.bramble.api.sync.RecordReaderFactory;
-import org.briarproject.bramble.api.sync.SyncRecordWriterFactory;
+import org.briarproject.bramble.api.sync.RecordWriterFactory;
 import org.briarproject.bramble.api.sync.SyncSessionFactory;
 import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.system.Clock;
@@ -52,23 +52,22 @@ public class SyncModule {
 	}
 	@Provides
-	SyncRecordReaderFactory provideRecordReaderFactory(
+	RecordReaderFactory provideRecordReaderFactory(
-			SyncRecordReaderFactoryImpl recordReaderFactory) {
+			RecordReaderFactoryImpl recordReaderFactory) {
 		return recordReaderFactory;
 	}
 	@Provides
-	SyncRecordWriterFactory provideRecordWriterFactory(
+	RecordWriterFactory provideRecordWriterFactory() {
-			SyncRecordWriterFactoryImpl recordWriterFactory) {
+		return new RecordWriterFactoryImpl();
 		return recordWriterFactory;
 	}
 	@Provides
 	@Singleton
 	SyncSessionFactory provideSyncSessionFactory(DatabaseComponent db,
 			@DatabaseExecutor Executor dbExecutor, EventBus eventBus,
-			Clock clock, SyncRecordReaderFactory recordReaderFactory,
+			Clock clock, RecordReaderFactory recordReaderFactory,
-			SyncRecordWriterFactory recordWriterFactory) {
+			RecordWriterFactory recordWriterFactory) {
 		return new SyncSessionFactoryImpl(db, dbExecutor, eventBus, clock,
 				recordReaderFactory, recordWriterFactory);
 	}
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordReaderFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordReaderFactoryImpl.java
@@ -1,34 +0,0 @@
 package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.RecordReader;
 import org.briarproject.bramble.api.record.RecordReaderFactory;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
 import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
 import java.io.InputStream;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
@Immutable
@NotNullByDefault
 class SyncRecordReaderFactoryImpl implements SyncRecordReaderFactory {
 	private final MessageFactory messageFactory;
 	private final RecordReaderFactory recordReaderFactory;
 	@Inject
 	SyncRecordReaderFactoryImpl(MessageFactory messageFactory,
 			RecordReaderFactory recordReaderFactory) {
 		this.messageFactory = messageFactory;
 		this.recordReaderFactory = recordReaderFactory;
 	}
 	@Override
 	public SyncRecordReader createRecordReader(InputStream in) {
 		RecordReader reader = recordReaderFactory.createRecordReader(in);
 		return new SyncRecordReaderImpl(messageFactory, reader);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordWriterFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordWriterFactoryImpl.java
@@ -1,28 +0,0 @@
 package org.briarproject.bramble.sync;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.record.RecordWriter;
 import org.briarproject.bramble.api.record.RecordWriterFactory;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncRecordWriterFactory;
 import java.io.OutputStream;
 import javax.inject.Inject;
@NotNullByDefault
 class SyncRecordWriterFactoryImpl implements SyncRecordWriterFactory {
 	private final RecordWriterFactory recordWriterFactory;
 	@Inject
 	SyncRecordWriterFactoryImpl(RecordWriterFactory recordWriterFactory) {
 		this.recordWriterFactory = recordWriterFactory;
 	}
 	@Override
 	public SyncRecordWriter createRecordWriter(OutputStream out) {
 		RecordWriter writer = recordWriterFactory.createRecordWriter(out);
 		return new SyncRecordWriterImpl(writer);
 	}
 }
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncSessionFactoryImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/SyncSessionFactoryImpl.java
@@ -5,10 +5,10 @@ import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.SyncRecordReader;
+import org.briarproject.bramble.api.sync.RecordReader;
-import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
+import org.briarproject.bramble.api.sync.RecordReaderFactory;
-import org.briarproject.bramble.api.sync.SyncRecordWriter;
+import org.briarproject.bramble.api.sync.RecordWriter;
-import org.briarproject.bramble.api.sync.SyncRecordWriterFactory;
+import org.briarproject.bramble.api.sync.RecordWriterFactory;
 import org.briarproject.bramble.api.sync.SyncSession;
 import org.briarproject.bramble.api.sync.SyncSessionFactory;
 import org.briarproject.bramble.api.system.Clock;
@@ -28,14 +28,14 @@ class SyncSessionFactoryImpl implements SyncSessionFactory {
 	private final Executor dbExecutor;
 	private final EventBus eventBus;
 	private final Clock clock;
-	private final SyncRecordReaderFactory recordReaderFactory;
+	private final RecordReaderFactory recordReaderFactory;
-	private final SyncRecordWriterFactory recordWriterFactory;
+	private final RecordWriterFactory recordWriterFactory;
 	@Inject
 	SyncSessionFactoryImpl(DatabaseComponent db,
 			@DatabaseExecutor Executor dbExecutor, EventBus eventBus,
-			Clock clock, SyncRecordReaderFactory recordReaderFactory,
+			Clock clock, RecordReaderFactory recordReaderFactory,
-			SyncRecordWriterFactory recordWriterFactory) {
+			RecordWriterFactory recordWriterFactory) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
@@ -46,16 +46,14 @@ class SyncSessionFactoryImpl implements SyncSessionFactory {
 	@Override
 	public SyncSession createIncomingSession(ContactId c, InputStream in) {
-		SyncRecordReader recordReader =
+		RecordReader recordReader = recordReaderFactory.createRecordReader(in);
 				recordReaderFactory.createRecordReader(in);
 		return new IncomingSession(db, dbExecutor, eventBus, c, recordReader);
 	}
 	@Override
 	public SyncSession createSimplexOutgoingSession(ContactId c,
 			int maxLatency, OutputStream out) {
-		SyncRecordWriter recordWriter =
+		RecordWriter recordWriter = recordWriterFactory.createRecordWriter(out);
 				recordWriterFactory.createRecordWriter(out);
 		return new SimplexOutgoingSession(db, dbExecutor, eventBus, c,
 				maxLatency, recordWriter);
 	}
@@ -63,8 +61,7 @@ class SyncSessionFactoryImpl implements SyncSessionFactory {
 	@Override
 	public SyncSession createDuplexOutgoingSession(ContactId c, int maxLatency,
 			int maxIdleTime, OutputStream out) {
-		SyncRecordWriter recordWriter =
+		RecordWriter recordWriter = recordWriterFactory.createRecordWriter(out);
 				recordWriterFactory.createRecordWriter(out);
 		return new DuplexOutgoingSession(db, dbExecutor, eventBus, clock, c,
 				maxLatency, maxIdleTime, recordWriter);
 	}
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/ValidationManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/ValidationManagerImpl.java
@@ -20,7 +20,6 @@ import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.sync.event.MessageAddedEvent;
 import org.briarproject.bramble.api.versioning.ClientMajorVersion;
 import java.util.Collection;
 import java.util.LinkedList;
@@ -52,8 +51,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	private final DatabaseComponent db;
 	private final Executor dbExecutor, validationExecutor;
 	private final MessageFactory messageFactory;
-	private final Map<ClientMajorVersion, MessageValidator> validators;
+	private final Map<ClientId, MessageValidator> validators;
-	private final Map<ClientMajorVersion, IncomingMessageHook> hooks;
+	private final Map<ClientId, IncomingMessageHook> hooks;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 	@Inject
@@ -82,15 +81,14 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	}
 	@Override
-	public void registerMessageValidator(ClientId c, int majorVersion,
+	public void registerMessageValidator(ClientId c, MessageValidator v) {
-			MessageValidator v) {
+		validators.put(c, v);
 		validators.put(new ClientMajorVersion(c, majorVersion), v);
 	}
 	@Override
-	public void registerIncomingMessageHook(ClientId c, int majorVersion,
+	public void registerIncomingMessageHook(ClientId c,
 			IncomingMessageHook hook) {
-		hooks.put(new ClientMajorVersion(c, majorVersion), hook);
+		hooks.put(c, hook);
 	}
 	private void validateOutstandingMessagesAsync() {
@@ -201,11 +199,9 @@ class ValidationManagerImpl implements ValidationManager, Service,
 						Message m = messageFactory.createMessage(id, raw);
 						Group g = db.getGroup(txn, m.getGroupId());
 						ClientId c = g.getClientId();
 						int majorVersion = g.getMajorVersion();
 						Metadata meta =
 								db.getMessageMetadataForValidator(txn, id);
-						DeliveryResult result =
+						DeliveryResult result = deliverMessage(txn, m, c, meta);
 								deliverMessage(txn, m, c, majorVersion, meta);
 						if (result.valid) {
 							pending.addAll(getPendingDependents(txn, id));
 							if (result.share) {
@@ -241,16 +237,14 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@ValidationExecutor
 	private void validateMessage(Message m, Group g) {
-		ClientMajorVersion cv =
+		MessageValidator v = validators.get(g.getClientId());
 				new ClientMajorVersion(g.getClientId(), g.getMajorVersion());
 		MessageValidator v = validators.get(cv);
 		if (v == null) {
-			if (LOG.isLoggable(WARNING)) LOG.warning("No validator for " + cv);
+			if (LOG.isLoggable(WARNING))
 				LOG.warning("No validator for " + g.getClientId().getString());
 		} else {
 			try {
 				MessageContext context = v.validateMessage(m, g);
-				storeMessageContextAsync(m, g.getClientId(),
+				storeMessageContextAsync(m, g.getClientId(), context);
 						g.getMajorVersion(), context);
 			} catch (InvalidMessageException e) {
 				if (LOG.isLoggable(INFO))
 					LOG.log(INFO, e.toString(), e);
@@ -262,13 +256,12 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	}
 	private void storeMessageContextAsync(Message m, ClientId c,
-			int majorVersion, MessageContext result) {
+			MessageContext result) {
-		dbExecutor.execute(() ->
+		dbExecutor.execute(() -> storeMessageContext(m, c, result));
 				storeMessageContext(m, c, majorVersion, result));
 	}
 	@DatabaseExecutor
-	private void storeMessageContext(Message m, ClientId c, int majorVersion,
+	private void storeMessageContext(Message m, ClientId c,
 			MessageContext context) {
 		try {
 			MessageId id = m.getId();
@@ -299,8 +292,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 					Metadata meta = context.getMetadata();
 					db.mergeMessageMetadata(txn, id, meta);
 					if (allDelivered) {
-						DeliveryResult result =
+						DeliveryResult result = deliverMessage(txn, m, c, meta);
 								deliverMessage(txn, m, c, majorVersion, meta);
 						if (result.valid) {
 							pending = getPendingDependents(txn, id);
 							if (result.share) {
@@ -332,11 +324,10 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private DeliveryResult deliverMessage(Transaction txn, Message m,
-			ClientId c, int majorVersion, Metadata meta) throws DbException {
+			ClientId c, Metadata meta) throws DbException {
 		// Deliver the message to the client if it's registered a hook
 		boolean shareMsg = false;
-		ClientMajorVersion cv = new ClientMajorVersion(c, majorVersion);
+		IncomingMessageHook hook = hooks.get(c);
 		IncomingMessageHook hook = hooks.get(cv);
 		if (hook != null) {
 			try {
 				shareMsg = hook.incomingMessage(txn, m, meta);
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
akwizgran	f25b16e680	Listen for wifi AP state changes. We won't necessarily receive a connectivity change event when the wifi AP is enabled.	2018-03-26 17:19:17 +01:00
akwizgran	467fdb6468	Log active network info.	2018-03-26 11:49:03 +01:00
akwizgran	c0840dc332	Log a lot of information about the network state.	2018-03-22 17:41:07 +00:00