Restrict getMessage() method to small messages.

.idea/codeStyles/Project.xml

@@ -31,15 +31,6 @@
       <option name="PACKAGES_TO_USE_STAR_IMPORTS">
         <value />
       </option>
-      <option name="PACKAGES_IMPORT_LAYOUT">
-        <value>
-          <package name="" alias="false" withSubpackages="true" />
-          <package name="java" alias="false" withSubpackages="true" />
-          <package name="javax" alias="false" withSubpackages="true" />
-          <package name="kotlin" alias="false" withSubpackages="true" />
-          <package name="" alias="true" withSubpackages="true" />
-        </value>
-      </option>
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT_FOR_MEMBERS" value="2147483647" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />

.idea/runConfigurations/All_tests.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.briar-android" />
+    <module name="briar-android" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />

.idea/runConfigurations/All_tests_in_bramble_android.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-android" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-android" />
+    <module name="bramble-android" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-android" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_api.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-api" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-api" />
+    <module name="bramble-api" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-api" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_core.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-core" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-core" />
+    <module name="bramble-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-core" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_java.xml

@@ -1,6 +1,8 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-java" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-java" />
+    <module name="bramble-java" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
@@ -8,8 +10,11 @@
     <option name="VM_PARAMETERS" value="-ea -Djava.library.path=libs" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-java" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_android.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-android" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.briar-android" />
+    <module name="briar-android" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-android" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_core.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-core" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.briar-core" />
+    <module name="briar-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-core" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_headless.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-headless" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.briar-headless" />
+    <module name="briar-headless" />
     <option name="PACKAGE_NAME" value="org.briarproject.briar.headless" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />

.idea/runConfigurations/H2_Performance_Test.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="H2 Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-core" />
+    <module name="bramble-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.H2DatabasePerformanceTest" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="class" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/HyperSQL_Performance_Test.xml

@@ -1,14 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="HyperSQL Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar.bramble-core" />
+    <module name="bramble-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.HyperSqlDatabasePerformanceTest" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="class" />
+    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <patterns />
+    <method />
   </configuration>
 </component>

.idea/runConfigurations/briar_headless.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="briar-headless" type="JetRunConfigurationType" singleton="true">
-    <module name="briar.briar-headless" />
+  <configuration default="false" name="briar-headless" type="JetRunConfigurationType" factoryName="Kotlin" singleton="true">
+    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
     <option name="VM_PARAMETERS" value="" />
     <option name="PROGRAM_PARAMETERS" value="-v" />
     <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
@@ -8,8 +8,9 @@
     <option name="PASS_PARENT_ENVS" value="true" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.briar.headless.MainKt" />
     <option name="WORKING_DIRECTORY" value="" />
-    <method v="2">
-      <option name="Make" enabled="true" />
+    <module name="briar-headless" />
+    <envs />
+    <method>
       <option name="Gradle.BeforeRunTask" enabled="true" tasks="jar" externalProjectPath="$PROJECT_DIR$/briar-headless" vmOptions="" scriptParameters="" />
     </method>
   </configuration>

bramble-android/build.gradle

@@ -38,7 +38,7 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.12@zip'
+	tor 'org.briarproject:tor-android:0.3.5.10@zip'
 	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

bramble-android/witness.gradle

@@ -1,36 +1,33 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:27.1.1:protos-27.1.1.jar:13f77e73762e58ab372d140b3a6be6903aea9775b62dd14fbc62d4cc7069c9a4',
-        'com.android.tools.analytics-library:shared:27.1.1:shared-27.1.1.jar:82930a52001410e97d809930b670f4de3002286975f046b9de5f6b777b06d366',
-        'com.android.tools.analytics-library:tracker:27.1.1:tracker-27.1.1.jar:31bc5a00be0055bac89c9b2f34751883e987cd89e3ac1783720645c164f591d9',
-        'com.android.tools.build:aapt2-proto:4.1.0-alpha01-6193524:aapt2-proto-4.1.0-alpha01-6193524.jar:17e75523e1e92dd4f222c7368ee41df9e964a508232f591e265d0c499baf9dca',
-        'com.android.tools.build:apksig:4.1.1:apksig-4.1.1.jar:e0a69da9e5a03986d608b45bbf954ef0e6a0b3f58c1b8315bd169ec08b279e72',
-        'com.android.tools.build:apkzlib:4.1.1:apkzlib-4.1.1.jar:ba4b5e419b6be0130eae7f8301c3a551ad3976f487d2e0c6852ebb175ac41127',
-        'com.android.tools.build:builder-model:4.1.1:builder-model-4.1.1.jar:e95c99cc298ad67b8deb6ced99c51abc8f59afebedad044b1a10dde14646a4dd',
-        'com.android.tools.build:builder-test-api:4.1.1:builder-test-api-4.1.1.jar:464f596ab261c051c3847406748e843770dea123f6fa5fee8a9390644e709b7a',
-        'com.android.tools.build:builder:4.1.1:builder-4.1.1.jar:0f78d4759d2f7b57b95865522ec34596ba419b9982f3b25e3449213f9c98b80d',
-        'com.android.tools.build:gradle-api:4.1.1:gradle-api-4.1.1.jar:d42e6b539e4c1353ad3546e75ec8ce11a017b97481023e8ea18577eefe374358',
-        'com.android.tools.build:manifest-merger:27.1.1:manifest-merger-27.1.1.jar:7a45fa143687859bb2e5a961dcf6ee88094d3853de0cb543dc03dbcb0f4b554b',
-        'com.android.tools.ddms:ddmlib:27.1.1:ddmlib-27.1.1.jar:da6e4bd834b6a85dae8019039849d8bd96933347dfbf460df74913ddade6e40a',
-        'com.android.tools.external.com-intellij:intellij-core:27.1.1:intellij-core-27.1.1.jar:2591a7363c4443c59bf9f793730acafce9d6ec3076e2f46716edaf53a41b6fb6',
-        'com.android.tools.external.com-intellij:kotlin-compiler:27.1.1:kotlin-compiler-27.1.1.jar:5054ae770ba788f110303c65abd6b1fa28eccf52dee1274510e201b2b81885c8',
-        'com.android.tools.external.org-jetbrains:uast:27.1.1:uast-27.1.1.jar:54cd8f6886a9d2f5641659dd5c91f626629672cd48301f7f0bd6aad9bd448714',
-        'com.android.tools.layoutlib:layoutlib-api:27.1.1:layoutlib-api-27.1.1.jar:8a9a22e3b309521ea83b724e5a89cfdac6076f52d675c0e17d77b05527bc0f8c',
-        'com.android.tools.lint:lint-api:27.1.1:lint-api-27.1.1.jar:c1d8176094cb0478786070d40533efb578ebc53529a82f6ef5bee879bdca418b',
-        'com.android.tools.lint:lint-checks:27.1.1:lint-checks-27.1.1.jar:3899c91e00bd059b40c31a9ca00cd0f8303191947608735ae1b657323693fb61',
-        'com.android.tools.lint:lint-gradle-api:27.1.1:lint-gradle-api-27.1.1.jar:26aa89d38b9825cc73229daa82a68875801c8b8491f30497ce62aff1f206eb0d',
-        'com.android.tools.lint:lint-gradle:27.1.1:lint-gradle-27.1.1.jar:f7355823ead869f4d28184ba28b7a0c693b507519a2d3705bb9848a0f35b3756',
-        'com.android.tools.lint:lint-model:27.1.1:lint-model-27.1.1.jar:bc23c0c413bdfca59dac2cd56b870d8360d009e9ec0d365e71f774bcf127971d',
-        'com.android.tools.lint:lint:27.1.1:lint-27.1.1.jar:2f6038a5398a42bd591883c3f5e5894f4ec52ca1c3683bf94fa8553c1700af81',
-        'com.android.tools:annotations:27.1.1:annotations-27.1.1.jar:ff28c504d2acb9fd1a5ffbd97ae85cf59ee18c76927525aad250509bccf2cab1',
-        'com.android.tools:common:27.1.1:common-27.1.1.jar:63d9a2a9ad6d278db319f3749b9f50bdf5457ef7020074a1bebe124e714b535c',
-        'com.android.tools:dvlib:27.1.1:dvlib-27.1.1.jar:998a54201fc1cefee5f2399215e95c42b1f64f9e1d8f4452eb8255c68ba5440f',
-        'com.android.tools:repository:27.1.1:repository-27.1.1.jar:d25b74ccabf4d876903efb375e9af6fb380d8ae0445bb74bbdcc225c1e37fa1d',
-        'com.android.tools:sdk-common:27.1.1:sdk-common-27.1.1.jar:4473ae97d0ef7061ee1de61041d5aa97405ae08e44c09cf7bb278b42e4b97c7c',
-        'com.android.tools:sdklib:27.1.1:sdklib-27.1.1.jar:08e6b83961ac9724b3c1e3d0eff971f13be6701292c77914b8794480f3391250',
-        'com.android:signflinger:4.1.1:signflinger-4.1.1.jar:0c66825988873ec2d51057fa463f54a8f18fc7326ff4530b9da363b71e97ce60',
-        'com.android:zipflinger:4.1.1:zipflinger-4.1.1.jar:0a8c3e52ac13dd031236f9fb5ba4408b1d5dcd12325a05440b36da09d8881446',
+        'com.android.tools.analytics-library:protos:26.5.1:protos-26.5.1.jar:8dde1130725461fe827f2a343d353f2b51e8870661fc860d7d5ebddb097ead4e',
+        'com.android.tools.analytics-library:shared:26.5.1:shared-26.5.1.jar:ccc2f3b00ec17b11401610ba68553544fc8fc517120e84439ac6eb86b875e18d',
+        'com.android.tools.analytics-library:tracker:26.5.1:tracker-26.5.1.jar:3a76984c0fe2e847ca7a8b35b4780ef0447a9d1666946cb8e60466318e0ab5ae',
+        'com.android.tools.build:aapt2-proto:0.4.0:aapt2-proto-0.4.0.jar:fac0435e08898f89eeeb9ca236bea707155ff816c12205ced285ad53604133ca',
+        'com.android.tools.build:apksig:3.5.1:apksig-3.5.1.jar:1fd33e7f009a2a0da766cfeec4211a09f548034b015c289a66d75dd8a9302f4a',
+        'com.android.tools.build:apkzlib:3.5.1:apkzlib-3.5.1.jar:9f330167cbe973b7db407692f74f4f6453b7ffa5f2048934b06280c2ceee60fa',
+        'com.android.tools.build:builder-model:3.5.1:builder-model-3.5.1.jar:39ea3c82b76b6e0c9f9fa88d93e0edc1dd4a0f1dfae0ef6fbf2d451da47e5450',
+        'com.android.tools.build:builder-test-api:3.5.1:builder-test-api-3.5.1.jar:a1b59305584cbcaa078fdc9cfb80871012755b822dd32e8da19add6f7bbcb762',
+        'com.android.tools.build:builder:3.5.1:builder-3.5.1.jar:e3a8d382434c5f60990730c4719fc814e85a898a33a1e96c1df8d627d3c6eea6',
+        'com.android.tools.build:gradle-api:3.5.1:gradle-api-3.5.1.jar:be9b41859bace11998f66b04ed944f87e413f3ad6da3c4665587699da125addc',
+        'com.android.tools.build:manifest-merger:26.5.1:manifest-merger-26.5.1.jar:dcad9ecb967251f4d750f55a4204a2b400e8fbfe5cb930a1d0d5dbe10ae8bdfc',
+        'com.android.tools.ddms:ddmlib:26.5.1:ddmlib-26.5.1.jar:b081aef2a4ed3f4d47cae4cdb128469735f25a114e026d37123bf9ffdec742a8',
+        'com.android.tools.external.com-intellij:intellij-core:26.5.1:intellij-core-26.5.1.jar:20eced30adc124805bd93488d9cd9d3e33e6bf7b48e9fe5a703d4983f894d450',
+        'com.android.tools.external.com-intellij:kotlin-compiler:26.5.1:kotlin-compiler-26.5.1.jar:5aed762dd54875b77ae7018d97c05756ff0c5b9fd02ec595dd396ccd14cc22cb',
+        'com.android.tools.external.org-jetbrains:uast:26.5.1:uast-26.5.1.jar:4bc8653d6c0943f40fee963a149e36c6baa45683d2530968a13f5007e3c40740',
+        'com.android.tools.layoutlib:layoutlib-api:26.5.1:layoutlib-api-26.5.1.jar:88732f11396c427273e515d23042e35633f4fe4295528a99b866aa2adf0efd9c',
+        'com.android.tools.lint:lint-api:26.5.1:lint-api-26.5.1.jar:ec33fcd72bfaf70dd841e03fbfd93f109c2e575aec146067c606689c3972f0de',
+        'com.android.tools.lint:lint-checks:26.5.1:lint-checks-26.5.1.jar:a1b9607d484aaae7a71dcecdc76f8003d8239af226c776894a2cf63f9e6c60d7',
+        'com.android.tools.lint:lint-gradle-api:26.5.1:lint-gradle-api-26.5.1.jar:82453fd98a8394cc84ed995c04d2cd744abd1d6589403427ba7eef53115406f3',
+        'com.android.tools.lint:lint-gradle:26.5.1:lint-gradle-26.5.1.jar:59465b56cf7db77c656d5f8195d721c3d48b6bdd0502d774de335bfe4baff00b',
+        'com.android.tools.lint:lint:26.5.1:lint-26.5.1.jar:336e4b04ec6f8b0f25879131b7a7862d77df83a1879ee5b71be26128755f8e2e',
+        'com.android.tools:annotations:26.5.1:annotations-26.5.1.jar:2c43c82f8c59d8f7a61e3239e1a2dc9f69dc342ec09af9b7c9f69b25337c0b6e',
+        'com.android.tools:common:26.5.1:common-26.5.1.jar:eccfa54486ed54c4e3123cc42195d023bd0dd21bcd2f0e4868e8c6fc70f8ef6b',
+        'com.android.tools:dvlib:26.5.1:dvlib-26.5.1.jar:46f93ad498b4756e7d867d2fe38c38890a80e7407a4ae459e4a8c8d5c5aeacfe',
+        'com.android.tools:repository:26.5.1:repository-26.5.1.jar:2b3ee791aa4c3e8ce60498c161a27ca7228816fc630eed4d9f25f2f36a106dce',
+        'com.android.tools:sdk-common:26.5.1:sdk-common-26.5.1.jar:365f749676c3574676fd465177c8a492f340816db2b520d6ed114d3b6e77bea7',
+        'com.android.tools:sdklib:26.5.1:sdklib-26.5.1.jar:007da104afb27c8c682a1628023fe9ec438249c8d15ef0fd6624c5bb8e23b696',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
         'com.google.code.gson:gson:2.8.5:gson-2.8.5.jar:233a0149fc365c9f6edbd683cfe266b19bdc773be98eabdaf6b3c924b48e7d81',
         'com.google.dagger:dagger-compiler:2.24:dagger-compiler-2.24.jar:3c5afb955fb188da485cb2c048eff37dce0e1530b9780a0f2f7187d16d1ccc1f',
@@ -38,30 +35,27 @@ dependencyVerification {
         'com.google.dagger:dagger-spi:2.24:dagger-spi-2.24.jar:c038445d14dbcb4054e61bf49e05009edf26fce4fdc7ec1a9db544784f68e718',
         'com.google.dagger:dagger:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
         'com.google.errorprone:error_prone_annotations:2.2.0:error_prone_annotations-2.2.0.jar:6ebd22ca1b9d8ec06d41de8d64e0596981d9607b42035f9ed374f9de271a481a',
-        'com.google.errorprone:error_prone_annotations:2.3.2:error_prone_annotations-2.3.2.jar:357cd6cfb067c969226c442451502aee13800a24e950fdfde77bcdb4565a668d',
         'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
         'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
         'com.google.guava:failureaccess:1.0.1:failureaccess-1.0.1.jar:a171ee4c734dd2da837e4b16be9df4661afab72a41adaf31eb84dfdaf936ca26',
+        'com.google.guava:guava:27.0.1-jre:guava-27.0.1-jre.jar:e1c814fd04492a27c38e0317eabeaa1b3e950ec8010239e400fe90ad6c9107b4',
         'com.google.guava:guava:27.1-jre:guava-27.1-jre.jar:4a5aa70cc968a4d137e599ad37553e5cfeed2265e8c193476d7119036c536fe7',
-        'com.google.guava:guava:28.1-jre:guava-28.1-jre.jar:30beb8b8527bd07c6e747e77f1a92122c2f29d57ce347461a4a55eb26e382da4',
         'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava:listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
-        'com.google.j2objc:j2objc-annotations:1.3:j2objc-annotations-1.3.jar:21af30c92267bd6122c0e0b4d20cccb6641a37eaf956c6540ec471d584e64a7b',
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
-        'com.google.protobuf:protobuf-java:3.10.0:protobuf-java-3.10.0.jar:161d7d61a8cb3970891c299578702fd079646e032329d6c2cabf998d191437c9',
+        '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:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
         '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:3.0.7:istack-commons-runtime-3.0.7.jar:6443e10ba2e259fb821d9b6becf10db5316285fc30c53cec9d7b19a3877e7fdf',
-        'com.sun.xml.fastinfoset:FastInfoset:1.2.15:FastInfoset-1.2.15.jar:785861db11ca1bd0d1956682b974ad73eb19cd3e01a4b3fa82d62eca97210aec',
+        '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:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
         'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
         'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
-        'javax.activation:javax.activation-api:1.2.0:javax.activation-api-1.2.0.jar:43fdef0b5b6ceb31b0424b208b930c74ab58fac2ceeb7b3f6fd3aeb8b5ca4393',
         '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:2.3.1:jaxb-api-2.3.1.jar:88b955a0df57880a26a74708bc34f74dcaf8ebf4e78843a28b50eae945732b06',
+        'javax.xml.bind:jaxb-api:2.2.12-b140109.1041:jaxb-api-2.2.12-b140109.1041.jar:b5e60cd8b7b5ff01ce4a74c5dd008f4fbd14ced3495d0b47b85cfedc182211f2',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'net.ltgt.gradle.incap:incap:0.2:incap-0.2.jar:b625b9806b0f1e4bc7a2e3457119488de3cd57ea20feedd513db070a573a4ffd',
         'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
@@ -76,35 +70,34 @@ dependencyVerification {
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
         'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
-        'org.briarproject:tor-android:0.3.5.12:tor-android-0.3.5.12.zip:db71fb3290acff79d572af0752570eaf6aad7c4d88c9b9aa0b4d5afe2b9ead9c',
+        'org.briarproject:tor-android:0.3.5.10:tor-android-0.3.5.10.zip:edd83bf557fcff2105eaa0bdb3f607a6852ebe7360920929ae3039dd5f4774c5',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
-        'org.checkerframework:checker-qual:2.8.1:checker-qual-2.8.1.jar:9103499008bcecd4e948da29b17864abb64304e15706444ae209d17ebe0575df',
         'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
-        'org.codehaus.mojo:animal-sniffer-annotations:1.18:animal-sniffer-annotations-1.18.jar:47f05852b48ee9baefef80fa3d8cea60efa4753c0013121dd7fe5eef2e5c729d',
-        'org.glassfish.jaxb:jaxb-runtime:2.3.1:jaxb-runtime-2.3.1.jar:45fecfa5c8217ce1f3652ab95179790ec8cc0dec0384bca51cbeb94a293d9f2f',
-        'org.glassfish.jaxb:txw2:2.3.1:txw2-2.3.1.jar:34975dde1c6920f1a39791142235689bc3cd357e24d05edd8ff93b885bd68d60',
+        '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.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.72:kotlin-reflect-1.3.72.jar:a188d9367de1c4ee9479db630985c0597b20709c83161b1430d24edb27e38c40',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.72:kotlin-stdlib-common-1.3.72.jar:5e7d1552863e480c1628b1cc39ce230ef829f5b7230106215a05acda5172203a',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.72:kotlin-stdlib-jdk7-1.3.72.jar:40566c0c08d414b9413ba556ff7f8a0b04b98b9f0f424d122dd2088510efccc4',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72:kotlin-stdlib-jdk8-1.3.72.jar:133da70cfc07b56094282eac5c59bccd59f167ee2ead22e5282876d8bc10bf95',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.72:kotlin-stdlib-1.3.72.jar:3856a7349ebacd6d1be6802b2fed9c4dc2c5a564ea92b6b945ac988243d4b16b',
+        'org.jetbrains.kotlin:kotlin-reflect:1.3.50:kotlin-reflect-1.3.50.jar:64583199ea5a54aefd1bd1595288925f784226ee562d1dd279011c6075b3d7a4',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.50:kotlin-stdlib-common-1.3.50.jar:8ce678e88e4ba018b66dacecf952471e4d7dfee156a8a819760a5a5ff29d323c',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.50:kotlin-stdlib-jdk7-1.3.50.jar:9a026639e76212f8d57b86d55b075394c2e009f1979110751d34c05c5f75d57b',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.50:kotlin-stdlib-jdk8-1.3.50.jar:1b351fb6e09c14b55525c74c1f4cf48942eae43c348b7bc764a5e6e423d4da0c',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.3.50:kotlin-stdlib-1.3.50.jar:e6f05746ee0366d0b52825a090fac474dcf44082c9083bbb205bd16976488d6c',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
         'org.jmock:jmock-legacy:2.8.2:jmock-legacy-2.8.2.jar:f2b985a5c08a9edb7f37612330c058809da3f6a6d63ce792426ebf8ff0d6d31b',
         'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
         'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
-        'org.jvnet.staxex:stax-ex:1.8:stax-ex-1.8.jar:95b05d9590af4154c6513b9c5dc1fb2e55b539972ba0a9ef28e9a0c01d83ad77',
+        'org.jvnet.staxex:stax-ex:1.7.7:stax-ex-1.7.7.jar:a31ff7d77163c0deb09e7fee59ad35ae44c2cee2cc8552a116ccd1583d813fb4',
         'org.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
-        'org.ow2.asm:asm-analysis:7.0:asm-analysis-7.0.jar:e981f8f650c4d900bb033650b18e122fa6b161eadd5f88978d08751f72ee8474',
-        'org.ow2.asm:asm-commons:7.0:asm-commons-7.0.jar:fed348ef05958e3e846a3ac074a12af5f7936ef3d21ce44a62c4fa08a771927d',
-        'org.ow2.asm:asm-tree:7.0:asm-tree-7.0.jar:cfd7a0874f9de36a999c127feeadfbfe6e04d4a71ee954d7af3d853f0be48a6c',
-        'org.ow2.asm:asm-util:7.0:asm-util-7.0.jar:75fbbca440ef463f41c2b0ab1a80abe67e910ac486da60a7863cbcb5bae7e145',
+        'org.ow2.asm:asm-analysis:6.0:asm-analysis-6.0.jar:2f1a6387219c3a6cc4856481f221b03bd9f2408a326d416af09af5d6f608c1f4',
+        'org.ow2.asm:asm-commons:6.0:asm-commons-6.0.jar:f1bce5c648a96a017bdcd01fe5d59af9845297fd7b79b81c015a6fbbd9719abf',
+        'org.ow2.asm:asm-tree:6.0:asm-tree-6.0.jar:887998fb69727c8759e4d253f856822801e33f9fd4caa566b3ac58ee92106215',
+        'org.ow2.asm:asm-util:6.0:asm-util-6.0.jar:356afebdb0f870175262e5188f8709a3b17aa2a5a6a4b0340b04d4b449bca5f6',
         'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
-        'org.ow2.asm:asm:7.0:asm-7.0.jar:b88ef66468b3c978ad0c97fd6e90979e56155b4ac69089ba7a44e9aa7ffe9acf',
+        'org.ow2.asm:asm:6.0:asm-6.0.jar:dd8971c74a4e697899a8e95caae4ea8760ea6c486dc6b97b1795e75760420461',
     ]
 }

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.api.client;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -36,24 +35,24 @@ public interface ClientHelper {
 
 	Message createMessageForStoringMetadata(GroupId g);
 
-	Message getMessage(MessageId m) throws DbException;
+	Message getSmallMessage(MessageId m) throws DbException;
 
-	Message getMessage(Transaction txn, MessageId m) throws DbException;
+	Message getSmallMessage(Transaction txn, MessageId m) throws DbException;
 
-	BdfList getMessageAsList(MessageId m) throws DbException, FormatException;
+	BdfList getSmallMessageAsList(MessageId m)
+			throws DbException, FormatException;
 
-	BdfList getMessageAsList(Transaction txn, MessageId m) throws DbException,
-			FormatException;
+	BdfList getSmallMessageAsList(Transaction txn, MessageId m)
+			throws DbException, FormatException;
 
-	BdfDictionary getGroupMetadataAsDictionary(GroupId g) throws DbException,
-			FormatException;
+	BdfDictionary getGroupMetadataAsDictionary(GroupId g)
+			throws DbException, FormatException;
 
 	BdfDictionary getGroupMetadataAsDictionary(Transaction txn, GroupId g)
 			throws DbException, FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(MessageId m)
-			throws DbException,
-			FormatException;
+			throws DbException, FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(Transaction txn, MessageId m)
 			throws DbException, FormatException;
@@ -68,8 +67,8 @@ public interface ClientHelper {
 			BdfDictionary query) throws DbException, FormatException;
 
 	Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
-			Transaction txn, GroupId g, BdfDictionary query) throws DbException,
-			FormatException;
+			Transaction txn, GroupId g, BdfDictionary query)
+			throws DbException, FormatException;
 
 	void mergeGroupMetadata(GroupId g, BdfDictionary metadata)
 			throws DbException, FormatException;
@@ -120,17 +119,4 @@ public interface ClientHelper {
 	Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException;
 
-	/**
-	 * Retrieves the contact ID from the group metadata of the given contact
-	 * group.
-	 */
-	ContactId getContactId(Transaction txn, GroupId contactGroupId)
-		throws DbException, FormatException;
-
-	/**
-	 * Stores the given contact ID in the group metadata of the given contact
-	 * group.
-	 */
-	void setContactId(Transaction txn, GroupId contactGroupId, ContactId c)
-		throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupConstants.java

@@ -1,9 +0,0 @@
-package org.briarproject.bramble.api.client;
-
-public interface ContactGroupConstants {
-
-	/**
-	 * Group metadata key for associating a contact ID with a contact group.
-	 */
-	String GROUP_KEY_CONTACT_ID = "contactId";
-}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -163,19 +163,23 @@ public interface DatabaseComponent extends TransactionManager {
 	 * less than or equal to the given length, for transmission over a
 	 * transport with the given maximum latency. Returns null if there are no
 	 * sendable messages that fit in the given length.
+	 *
+	 * @param small True if only single-block messages should be sent
 	 */
 	@Nullable
 	Collection<Message> generateBatch(Transaction txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException;
+			int maxLength, int maxLatency, boolean small) throws DbException;
 
 	/**
 	 * Returns an offer for the given contact for transmission over a
 	 * transport with the given maximum latency, or null if there are no
 	 * messages to offer.
+	 *
+	 * @param small True if only single-block messages should be offered
 	 */
 	@Nullable
 	Offer generateOffer(Transaction txn, ContactId c, int maxMessages,
-			int maxLatency) throws DbException;
+			int maxLatency, boolean small) throws DbException;
 
 	/**
 	 * Returns a request for the given contact, or null if there are no
@@ -272,13 +276,14 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<Identity> getIdentities(Transaction txn) throws DbException;
 
 	/**
-	 * Returns the message with the given ID.
+	 * Returns the single-block message with the given ID.
 	 * <p/>
 	 * Read-only.
 	 *
 	 * @throws MessageDeletedException if the message has been deleted
+	 * @throws MessageTooLargeException if the message has more than one block
 	 */
-	Message getMessage(Transaction txn, MessageId m) throws DbException;
+	Message getSmallMessage(Transaction txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the IDs of all delivered messages in the given group.

bramble-api/src/main/java/org/briarproject/bramble/api/db/MessageTooLargeException.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when a multi-block message is requested from the database via a
+ * method that is only suitable for requesting single-block messages.
+ */
+public class MessageTooLargeException extends DbException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncConstants.java

@@ -29,10 +29,15 @@ public interface SyncConstants {
 	 */
 	int MESSAGE_HEADER_LENGTH = UniqueId.LENGTH + 8;
 
+	/**
+	 * The maximum length of a block in bytes.
+	 */
+	int MAX_BLOCK_LENGTH = 32 * 1024; // 32 KiB
+
 	/**
 	 * The maximum length of a message body in bytes.
 	 */
-	int MAX_MESSAGE_BODY_LENGTH = 32 * 1024; // 32 KiB
+	int MAX_MESSAGE_BODY_LENGTH = MAX_BLOCK_LENGTH;
 
 	/**
 	 * The maximum length of a message in bytes.

bramble-api/src/main/java/org/briarproject/bramble/util/ValidationUtils.java

@@ -6,9 +6,7 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.Immutable;
 
-@Immutable
 @NotNullByDefault
 public class ValidationUtils {
 
@@ -66,9 +64,4 @@ public class ValidationUtils {
 		if (dictionary != null && dictionary.size() != size)
 			throw new FormatException();
 	}
-
-	public static void checkRange(@Nullable Long l, long min, long max)
-			throws FormatException {
-		if (l != null && (l < min || l > max)) throw new FormatException();
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -2,13 +2,11 @@ package org.briarproject.bramble.client;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
-import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
-import org.briarproject.bramble.api.data.BdfEntry;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
@@ -41,7 +39,6 @@ import java.util.Map.Entry;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
-import static org.briarproject.bramble.api.client.ContactGroupConstants.GROUP_KEY_CONTACT_ID;
 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;
@@ -119,25 +116,27 @@ class ClientHelperImpl implements ClientHelper {
 	}
 
 	@Override
-	public Message getMessage(MessageId m) throws DbException {
-		return db.transactionWithResult(true, txn -> getMessage(txn, m));
+	public Message getSmallMessage(MessageId m) throws DbException {
+		return db.transactionWithResult(true, txn -> getSmallMessage(txn, m));
 	}
 
 	@Override
-	public Message getMessage(Transaction txn, MessageId m) throws DbException {
-		return db.getMessage(txn, m);
+	public Message getSmallMessage(Transaction txn, MessageId m)
+			throws DbException {
+		return db.getSmallMessage(txn, m);
 	}
 
 	@Override
-	public BdfList getMessageAsList(MessageId m) throws DbException,
-			FormatException {
-		return db.transactionWithResult(true, txn -> getMessageAsList(txn, m));
-	}
-
-	@Override
-	public BdfList getMessageAsList(Transaction txn, MessageId m)
+	public BdfList getSmallMessageAsList(MessageId m)
 			throws DbException, FormatException {
-		return toList(db.getMessage(txn, m).getBody());
+		return db.transactionWithResult(true, txn ->
+				getSmallMessageAsList(txn, m));
+	}
+
+	@Override
+	public BdfList getSmallMessageAsList(Transaction txn, MessageId m)
+			throws DbException, FormatException {
+		return toList(db.getSmallMessage(txn, m).getBody());
 	}
 
 	@Override
@@ -392,27 +391,4 @@ class ClientHelperImpl implements ClientHelper {
 		return tpMap;
 	}
 
-	@Override
-	public ContactId getContactId(Transaction txn, GroupId contactGroupId)
-			throws DbException {
-		try {
-			BdfDictionary meta =
-					getGroupMetadataAsDictionary(txn, contactGroupId);
-			return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
-		} catch (FormatException e) {
-			throw new DbException(e); // Invalid group metadata
-		}
-	}
-
-	@Override
-	public void setContactId(Transaction txn, GroupId contactGroupId,
-			ContactId c) throws DbException {
-		BdfDictionary meta = BdfDictionary.of(
-				new BdfEntry(GROUP_KEY_CONTACT_ID, c.getInt()));
-		try {
-			mergeGroupMetadata(txn, contactGroupId, meta);
-		} catch (FormatException e) {
-			throw new AssertionError(e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MessageDeletedException;
+import org.briarproject.bramble.api.db.MessageTooLargeException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
@@ -332,13 +333,14 @@ interface Database<T> {
 	Collection<Identity> getIdentities(T txn) throws DbException;
 
 	/**
-	 * Returns the message with the given ID.
+	 * Returns the single-block message with the given ID.
 	 * <p/>
 	 * Read-only.
 	 *
 	 * @throws MessageDeletedException if the message has been deleted
+	 * @throws MessageTooLargeException if the message has more than one block
 	 */
-	Message getMessage(T txn, MessageId m) throws DbException;
+	Message getSmallMessage(T txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
@@ -456,6 +458,15 @@ interface Database<T> {
 	Collection<MessageId> getMessagesToOffer(T txn, ContactId c,
 			int maxMessages, int maxLatency) throws DbException;
 
+	/**
+	 * Returns the IDs of some single-block messages that are eligible to be
+	 * offered to the given contact, up to the given number of messages.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getSmallMessagesToOffer(T txn, ContactId c,
+			int maxMessages, int maxLatency) throws DbException;
+
 	/**
 	 * Returns the IDs of some messages that are eligible to be requested from
 	 * the given contact, up to the given number of messages.
@@ -474,6 +485,15 @@ interface Database<T> {
 	Collection<MessageId> getMessagesToSend(T txn, ContactId c, int maxLength,
 			int maxLatency) throws DbException;
 
+	/**
+	 * Returns the IDs of some single-block messages that are eligible to be
+	 * sent to the given contact, up to the given total length.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getSmallMessagesToSend(T txn, ContactId c,
+			int maxLength, int maxLatency) throws DbException;
+
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -406,16 +406,19 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateBatch(Transaction transaction,
-			ContactId c, int maxLength, int maxLatency) throws DbException {
+			ContactId c, int maxLength, int maxLatency, boolean small)
+			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		Collection<MessageId> ids =
-				db.getMessagesToSend(txn, c, maxLength, maxLatency);
+		Collection<MessageId> ids;
+		if (small)
+			ids = db.getSmallMessagesToSend(txn, c, maxLength, maxLatency);
+		else ids = db.getMessagesToSend(txn, c, maxLength, maxLatency);
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getMessage(txn, m));
+			messages.add(db.getSmallMessage(txn, m));
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
 		if (ids.isEmpty()) return null;
@@ -427,13 +430,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Offer generateOffer(Transaction transaction, ContactId c,
-			int maxMessages, int maxLatency) throws DbException {
+			int maxMessages, int maxLatency, boolean small) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		Collection<MessageId> ids =
-				db.getMessagesToOffer(txn, c, maxMessages, maxLatency);
+		Collection<MessageId> ids;
+		if (small)
+			ids = db.getSmallMessagesToOffer(txn, c, maxMessages, maxLatency);
+		else ids = db.getMessagesToOffer(txn, c, maxMessages, maxLatency);
 		if (ids.isEmpty()) return null;
 		for (MessageId m : ids)
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
@@ -448,8 +453,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		Collection<MessageId> ids = db.getMessagesToRequest(txn, c,
-				maxMessages);
+		Collection<MessageId> ids =
+				db.getMessagesToRequest(txn, c, maxMessages);
 		if (ids.isEmpty()) return null;
 		db.removeOfferedMessages(txn, c, ids);
 		return new Request(ids);
@@ -467,7 +472,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 				db.getRequestedMessagesToSend(txn, c, maxLength, maxLatency);
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getMessage(txn, m));
+			messages.add(db.getSmallMessage(txn, m));
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
 		if (ids.isEmpty()) return null;
@@ -559,12 +564,12 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Message getMessage(Transaction transaction, MessageId m)
+	public Message getSmallMessage(Transaction transaction, MessageId m)
 			throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
-		return db.getMessage(txn, m);
+		return db.getSmallMessage(txn, m);
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseModule.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.sql.Connection;
@@ -22,9 +21,8 @@ public class DatabaseModule {
 
 	@Provides
 	@Singleton
-	Database<Connection> provideDatabase(DatabaseConfig config,
-			MessageFactory messageFactory, Clock clock) {
-		return new H2Database(config, messageFactory, clock);
+	Database<Connection> provideDatabase(DatabaseConfig config, Clock clock) {
+		return new H2Database(config, clock);
 	}
 
 	@Provides

bramble-core/src/main/java/org/briarproject/bramble/db/H2Database.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
 
@@ -51,9 +50,8 @@ class H2Database extends JdbcDatabase {
 	private volatile SecretKey key = null;
 
 	@Inject
-	H2Database(DatabaseConfig config, MessageFactory messageFactory,
-			Clock clock) {
-		super(dbTypes, messageFactory, clock);
+	H2Database(DatabaseConfig config, Clock clock) {
+		super(dbTypes, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();

bramble-core/src/main/java/org/briarproject/bramble/db/HyperSqlDatabase.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
 
@@ -51,9 +50,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 	private volatile SecretKey key = null;
 
 	@Inject
-	HyperSqlDatabase(DatabaseConfig config, MessageFactory messageFactory,
-			Clock clock) {
-		super(dbTypes, messageFactory, clock);
+	HyperSqlDatabase(DatabaseConfig config, Clock clock) {
+		super(dbTypes, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -16,6 +16,7 @@ import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MessageDeletedException;
+import org.briarproject.bramble.api.db.MessageTooLargeException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
@@ -30,7 +31,6 @@ 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.Message;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.validation.MessageState;
@@ -76,6 +76,7 @@ import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 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.SyncConstants.MAX_BLOCK_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
 import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
@@ -98,7 +99,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 47;
+	static final int CODE_SCHEMA_VERSION = 48;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -180,8 +181,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
 					+ " temporary BOOLEAN NOT NULL,"
-					+ " length INT NOT NULL,"
-					+ " raw BLOB," // Null if message has been deleted
+					+ " length INT NOT NULL," // Includes message header
+					+ " deleted BOOLEAN NOT NULL,"
+					+ " blockCount INT NOT NULL,"
 					+ " PRIMARY KEY (messageId),"
 					+ " FOREIGN KEY (groupId)"
 					+ " REFERENCES groups (groupId)"
@@ -227,6 +229,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " REFERENCES contacts (contactId)"
 					+ " ON DELETE CASCADE)";
 
+	private static final String CREATE_BLOCKS =
+			"CREATE TABLE blocks"
+					+ " (messageId _HASH NOT NULL,"
+					+ " blockNumber INT NOT NULL,"
+					+ " blockLength INT NOT NULL," // Excludes block header
+					+ " data BLOB," // Null if message has been deleted
+					+ " PRIMARY KEY (messageId, blockNumber),"
+					+ " FOREIGN KEY (messageId)"
+					+ " REFERENCES messages (messageId)"
+					+ " ON DELETE CASCADE)";
+
 	private static final String CREATE_STATUSES =
 			"CREATE TABLE statuses"
 					+ " (messageId _HASH NOT NULL,"
@@ -339,7 +352,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final Logger LOG =
 			getLogger(JdbcDatabase.class.getName());
 
-	private final MessageFactory messageFactory;
 	private final Clock clock;
 	private final DatabaseTypes dbTypes;
 
@@ -359,10 +371,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	protected abstract void compactAndClose() throws DbException;
 
-	JdbcDatabase(DatabaseTypes databaseTypes, MessageFactory messageFactory,
-			Clock clock) {
+	JdbcDatabase(DatabaseTypes databaseTypes, Clock clock) {
 		this.dbTypes = databaseTypes;
-		this.messageFactory = messageFactory;
 		this.clock = clock;
 	}
 
@@ -440,10 +450,12 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Migrating from schema " + start + " to " + end);
 				if (listener != null) listener.onDatabaseMigration();
+				long startTime = now();
 				// Apply the migration
 				m.migrate(txn);
 				// Store the new schema version
 				storeSchemaVersion(txn, end);
+				logDuration(LOG, "Migration", startTime);
 				dataSchemaVersion = end;
 			}
 		}
@@ -463,7 +475,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration43_44(dbTypes),
 				new Migration44_45(),
 				new Migration45_46(),
-				new Migration46_47(dbTypes)
+				new Migration46_47(dbTypes),
+				new Migration47_48(dbTypes)
 		);
 	}
 
@@ -509,6 +522,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_MESSAGE_METADATA));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_MESSAGE_DEPENDENCIES));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_OFFERS));
+			s.executeUpdate(dbTypes.replaceTypes(CREATE_BLOCKS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_STATUSES));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_TRANSPORTS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_PENDING_CONTACTS));
@@ -726,7 +740,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId, timestamp, state, shared,"
-					+ " length, raw IS NULL"
+					+ " length, deleted"
 					+ " FROM messages"
 					+ " WHERE groupId = ?";
 			ps = txn.prepareStatement(sql);
@@ -788,8 +802,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
-					+ " state, shared, temporary, length, raw)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
+					+ " state, shared, temporary, length, deleted, blockCount)"
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?, FALSE, 1)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getId().getBytes());
 			ps.setBytes(2, m.getGroupId().getBytes());
@@ -797,12 +811,20 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setInt(4, state.getValue());
 			ps.setBoolean(5, shared);
 			ps.setBoolean(6, temporary);
-			byte[] raw = messageFactory.getRawMessage(m);
-			ps.setInt(7, raw.length);
-			ps.setBytes(8, raw);
+			ps.setInt(7, m.getRawLength());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
+			sql = "INSERT INTO blocks (messageId, blockNumber, blockLength,"
+					+ " data)"
+					+ " VALUES (?, 0, ?, ?)";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getId().getBytes());
+			ps.setInt(2, m.getBody().length);
+			ps.setBytes(3, m.getBody());
+			affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
 			// Create a status row for each contact that can see the group
 			Map<ContactId, Boolean> visibility =
 					getGroupVisibility(txn, m.getGroupId());
@@ -811,7 +833,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				boolean offered = removeOfferedMessage(txn, c, m.getId());
 				boolean seen = offered || c.equals(sender);
 				addStatus(txn, m.getId(), c, m.getGroupId(), m.getTimestamp(),
-						raw.length, state, e.getValue(), shared, false, seen);
+						m.getRawLength(), state, e.getValue(), shared, false,
+						seen);
 			}
 			// Update denormalised column in messageDependencies if dependency
 			// is in same group as dependent
@@ -1290,12 +1313,18 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public void deleteMessage(Connection txn, MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET raw = NULL WHERE messageId = ?";
+			String sql = "UPDATE messages SET deleted = TRUE"
+					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+			sql = "UPDATE blocks SET data = NULL WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
-			if (affected > 1) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in statuses
 			sql = "UPDATE statuses SET deleted = TRUE WHERE messageId = ?";
@@ -1688,11 +1717,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Message getMessage(Connection txn, MessageId m) throws DbException {
+	public Message getSmallMessage(Connection txn, MessageId m)
+			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT groupId, timestamp, raw FROM messages"
+			String sql = "SELECT groupId, timestamp, deleted, blockCount"
+					+ " FROM messages"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
@@ -1700,15 +1731,25 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (!rs.next()) throw new DbStateException();
 			GroupId g = new GroupId(rs.getBytes(1));
 			long timestamp = rs.getLong(2);
-			byte[] raw = rs.getBytes(3);
+			boolean deleted = rs.getBoolean(3);
+			int blockCount = rs.getInt(4);
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
-			if (raw == null) throw new MessageDeletedException();
-			if (raw.length <= MESSAGE_HEADER_LENGTH) throw new AssertionError();
-			byte[] body = new byte[raw.length - MESSAGE_HEADER_LENGTH];
-			System.arraycopy(raw, MESSAGE_HEADER_LENGTH, body, 0, body.length);
-			return new Message(m, g, timestamp, body);
+			if (deleted) throw new MessageDeletedException();
+			if (blockCount > 1) throw new MessageTooLargeException();
+			sql = "SELECT data FROM blocks"
+					+ " WHERE messageId = ? AND blockNumber = 0";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			byte[] data = rs.getBytes(1);
+			if (data == null) throw new DbStateException();
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return new Message(m, g, timestamp, data);
 		} catch (SQLException e) {
 			tryToClose(rs, LOG, WARNING);
 			tryToClose(ps, LOG, WARNING);
@@ -2100,6 +2141,42 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Collection<MessageId> getSmallMessagesToOffer(Connection txn,
+			ContactId c, int maxMessages, int maxLatency) throws DbException {
+		long now = clock.currentTimeMillis();
+		long eta = now + maxLatency;
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND length <= ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
+					+ " AND seen = FALSE AND requested = FALSE"
+					+ " AND (expiry <= ? OR eta > ?)"
+					+ " ORDER BY timestamp LIMIT ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			ps.setInt(3, MESSAGE_HEADER_LENGTH + MAX_BLOCK_LENGTH);
+			ps.setLong(4, now);
+			ps.setLong(5, eta);
+			ps.setInt(6, maxMessages);
+			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, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToRequest(Connection txn,
 			ContactId c, int maxMessages) throws DbException {
@@ -2164,6 +2241,47 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Collection<MessageId> getSmallMessagesToSend(Connection txn,
+			ContactId c, int maxLength, int maxLatency) throws DbException {
+		long now = clock.currentTimeMillis();
+		long eta = now + maxLatency;
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT length, messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND length <= ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
+					+ " AND seen = FALSE"
+					+ " AND (expiry <= ? OR eta > ?)"
+					+ " ORDER BY timestamp";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			ps.setInt(3, MESSAGE_HEADER_LENGTH + MAX_BLOCK_LENGTH);
+			ps.setLong(4, now);
+			ps.setLong(5, eta);
+			rs = ps.executeQuery();
+			List<MessageId> ids = new ArrayList<>();
+			int total = 0;
+			while (rs.next()) {
+				int length = rs.getInt(1);
+				if (total + length > maxLength) break;
+				ids.add(new MessageId(rs.getBytes(2)));
+				total += length;
+			}
+			rs.close();
+			ps.close();
+			return ids;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Connection txn)
 			throws DbException {
@@ -2182,7 +2300,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId FROM messages"
-					+ " WHERE state = ? AND raw IS NOT NULL";
+					+ " WHERE state = ? AND deleted = FALSE";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			rs = ps.executeQuery();

bramble-core/src/main/java/org/briarproject/bramble/db/Migration38_39.java

@@ -37,6 +37,7 @@ class Migration38_39 implements Migration<Connection> {
 			s.execute("ALTER TABLE incomingKeys"
 					+ " ALTER COLUMN contactId"
 					+ " SET NOT NULL");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration39_40.java

@@ -36,6 +36,7 @@ class Migration39_40 implements Migration<Connection> {
 			s.execute("ALTER TABLE statuses"
 					+ " ALTER COLUMN eta"
 					+ " SET NOT NULL");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration40_41.java

@@ -38,6 +38,7 @@ class Migration40_41 implements Migration<Connection> {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE contacts"
 					+ dbTypes.replaceTypes(" ADD alias _STRING"));
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration41_42.java

@@ -89,6 +89,7 @@ class Migration41_42 implements Migration<Connection> {
 					+ " FOREIGN KEY (keySetId)"
 					+ " REFERENCES outgoingHandshakeKeys (keySetId)"
 					+ " ON DELETE CASCADE)"));
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration42_43.java

@@ -44,6 +44,7 @@ class Migration42_43 implements Migration<Connection> {
 					+ " ADD COLUMN handshakePublicKey _BINARY"));
 			s.execute("ALTER TABLE contacts"
 					+ " DROP COLUMN active");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration43_44.java

@@ -50,6 +50,7 @@ class Migration43_44 implements Migration<Connection> {
 					+ " ADD COLUMN rootKey _SECRET"));
 			s.execute("ALTER TABLE outgoingKeys"
 					+ " ADD COLUMN alice BOOLEAN");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration44_45.java

@@ -31,6 +31,7 @@ class Migration44_45 implements Migration<Connection> {
 		try {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE pendingContacts DROP COLUMN state");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration45_46.java

@@ -32,6 +32,7 @@ class Migration45_46 implements Migration<Connection> {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE messages"
 					+ " ADD COLUMN temporary BOOLEAN DEFAULT FALSE NOT NULL");
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration46_47.java

@@ -39,6 +39,7 @@ class Migration46_47 implements Migration<Connection> {
 			s.execute(dbTypes.replaceTypes("ALTER TABLE contacts"
 					+ " ADD COLUMN syncVersions"
 					+ " _BINARY DEFAULT '00' NOT NULL"));
+			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration47_48.java

@@ -0,0 +1,95 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.lang.System.arraycopy;
+import static java.sql.Types.BINARY;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration47_48 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration47_48.class.getName());
+
+	private final DatabaseTypes dbTypes;
+
+	Migration47_48(DatabaseTypes dbTypes) {
+		this.dbTypes = dbTypes;
+	}
+
+	@Override
+	public int getStartVersion() {
+		return 47;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 48;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		ResultSet rs = null;
+		PreparedStatement ps = null;
+		try {
+			s = txn.createStatement();
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN deleted BOOLEAN DEFAULT FALSE NOT NULL");
+			s.execute("UPDATE messages SET deleted = TRUE WHERE raw IS NULL");
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN blockCount INT DEFAULT 1 NOT NULL");
+			s.execute(dbTypes.replaceTypes("CREATE TABLE blocks"
+					+ " (messageId _HASH NOT NULL,"
+					+ " blockNumber INT NOT NULL,"
+					+ " blockLength INT NOT NULL," // Excludes block header
+					+ " data BLOB," // Null if message has been deleted
+					+ " PRIMARY KEY (messageId, blockNumber),"
+					+ " FOREIGN KEY (messageId)"
+					+ " REFERENCES messages (messageId)"
+					+ " ON DELETE CASCADE)"));
+			rs = s.executeQuery("SELECT messageId, length, raw FROM messages");
+			ps = txn.prepareStatement("INSERT INTO blocks"
+					+ " (messageId, blockNumber, blockLength, data)"
+					+ " VALUES (?, 0, ?, ?)");
+			int migrated = 0;
+			while (rs.next()) {
+				byte[] id = rs.getBytes(1);
+				int length = rs.getInt(2);
+				byte[] raw = rs.getBytes(3);
+				ps.setBytes(1, id);
+				ps.setInt(2, length - MESSAGE_HEADER_LENGTH);
+				if (raw == null) {
+					ps.setNull(3, BINARY);
+				} else {
+					byte[] data = new byte[raw.length - MESSAGE_HEADER_LENGTH];
+					arraycopy(raw, MESSAGE_HEADER_LENGTH, data, 0, data.length);
+					ps.setBytes(3, data);
+				}
+				if (ps.executeUpdate() != 1) throw new DbStateException();
+				migrated++;
+			}
+			ps.close();
+			rs.close();
+			s.execute("ALTER TABLE messages DROP COLUMN raw");
+			s.close();
+			if (LOG.isLoggable(INFO))
+				LOG.info("Migrated " + migrated + " messages");
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java

@@ -199,7 +199,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			Map<TransportId, LatestUpdate> latest = findLatestLocal(txn);
 			// Retrieve and parse the latest local properties
 			for (Entry<TransportId, LatestUpdate> e : latest.entrySet()) {
-				BdfList message = clientHelper.getMessageAsList(txn,
+				BdfList message = clientHelper.getSmallMessageAsList(txn,
 						e.getValue().messageId);
 				local.put(e.getKey(), parseProperties(message));
 			}
@@ -220,7 +220,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 						true);
 				if (latest != null) {
 					// Retrieve and parse the latest local properties
-					BdfList message = clientHelper.getMessageAsList(txn,
+					BdfList message = clientHelper.getSmallMessageAsList(txn,
 							latest.messageId);
 					p = parseProperties(message);
 				}
@@ -250,7 +250,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			if (latest == null) {
 				local = new TransportProperties();
 			} else {
-				BdfList message = clientHelper.getMessageAsList(txn,
+				BdfList message = clientHelper.getSmallMessageAsList(txn,
 						latest.messageId);
 				local = parseProperties(message);
 			}
@@ -271,8 +271,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 				remote = new TransportProperties();
 			} else {
 				// Retrieve and parse the latest remote properties
-				BdfList message =
-						clientHelper.getMessageAsList(txn, latest.messageId);
+				BdfList message = clientHelper.getSmallMessageAsList(txn,
+						latest.messageId);
 				remote = parseProperties(message);
 			}
 			// Merge in any discovered properties
@@ -315,7 +315,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 					}
 					changed = true;
 				} else {
-					BdfList message = clientHelper.getMessageAsList(txn,
+					BdfList message = clientHelper.getSmallMessageAsList(txn,
 							latest.messageId);
 					TransportProperties old = parseProperties(message);
 					merged = new TransportProperties(old);

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -340,7 +340,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			try {
 				Offer o = db.transactionWithNullableResult(false, txn -> {
 					Offer offer = db.generateOffer(txn, contactId,
-							MAX_MESSAGE_IDS, maxLatency);
+							MAX_MESSAGE_IDS, maxLatency, true);
 					setNextSendTime(db.getNextSendTime(txn, contactId));
 					return offer;
 				});

bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java

@@ -186,7 +186,8 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 				Collection<Message> b =
 						db.transactionWithNullableResult(false, txn ->
 								db.generateBatch(txn, contactId,
-										MAX_RECORD_PAYLOAD_BYTES, maxLatency));
+										MAX_RECORD_PAYLOAD_BYTES, maxLatency,
+										true));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b == null) decrementOutstandingQueries();

bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java

@@ -120,7 +120,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 			Pair<Message, Group> mg = db.transactionWithResult(true, txn -> {
 				MessageId id = unvalidated.poll();
 				if (id == null) throw new AssertionError();
-				Message m = db.getMessage(txn, id);
+				Message m = db.getSmallMessage(txn, id);
 				Group g = db.getGroup(txn, m.getGroupId());
 				return new Pair<>(m, g);
 			});
@@ -179,7 +179,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 						invalidateMessage(txn, id);
 						addDependentsToInvalidate(txn, id, invalidate);
 					} else if (allDelivered) {
-						Message m = db.getMessage(txn, id);
+						Message m = db.getSmallMessage(txn, id);
 						Group g = db.getGroup(txn, m.getGroupId());
 						ClientId c = g.getClientId();
 						int majorVersion = g.getMajorVersion();

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningConstants.java

@@ -5,5 +5,6 @@ interface ClientVersioningConstants {
 	// Metadata keys
 	String MSG_KEY_UPDATE_VERSION = "version";
 	String MSG_KEY_LOCAL = "local";
+	String GROUP_KEY_CONTACT_ID = "contactId";
 }
 

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningManagerImpl.java

@@ -50,6 +50,7 @@ import static java.util.Collections.emptyList;
 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.versioning.ClientVersioningConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_LOCAL;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_UPDATE_VERSION;
 
@@ -160,7 +161,13 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 		db.addGroup(txn, g);
 		db.setGroupVisibility(txn, c.getId(), g.getId(), SHARED);
 		// Attach the contact ID to the group
-		clientHelper.setContactId(txn, g.getId(), c.getId());
+		BdfDictionary meta = new BdfDictionary();
+		meta.put(GROUP_KEY_CONTACT_ID, c.getId().getInt());
+		try {
+			clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
+		} catch (FormatException e) {
+			throw new AssertionError(e);
+		}
 		// Create and store the first local update
 		List<ClientVersion> versions = new ArrayList<>(clients);
 		Collections.sort(versions);
@@ -222,7 +229,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 			Map<ClientMajorVersion, Visibility> after =
 					getVisibilities(newLocalStates, newRemoteStates);
 			// Call hooks for any visibilities that have changed
-			ContactId c = clientHelper.getContactId(txn, m.getGroupId());
+			ContactId c = getContactId(txn, m.getGroupId());
 			if (!before.equals(after)) {
 				Contact contact = db.getContact(txn, c);
 				callVisibilityHooks(txn, contact, before, after);
@@ -291,7 +298,8 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 	private List<ClientVersion> loadClientVersions(Transaction txn,
 			MessageId m) throws DbException {
 		try {
-			return parseClientVersions(clientHelper.getMessageAsList(txn, m));
+			return parseClientVersions(
+					clientHelper.getSmallMessageAsList(txn, m));
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -384,7 +392,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 
 	private Update loadUpdate(Transaction txn, MessageId m) throws DbException {
 		try {
-			return parseUpdate(clientHelper.getMessageAsList(txn, m));
+			return parseUpdate(clientHelper.getSmallMessageAsList(txn, m));
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -514,6 +522,17 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 		storeUpdate(txn, g, states, 1);
 	}
 
+	private ContactId getContactId(Transaction txn, GroupId g)
+			throws DbException {
+		try {
+			BdfDictionary meta =
+					clientHelper.getGroupMetadataAsDictionary(txn, g);
+			return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	private List<ClientState> updateStatesFromRemoteStates(
 			List<ClientState> oldLocalStates, List<ClientState> remoteStates) {
 		Set<ClientMajorVersion> remoteSet = new HashSet<>();

bramble-core/src/test/java/org/briarproject/bramble/client/ClientHelperImplTest.java

@@ -122,11 +122,11 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		expectToList(true);
 		context.checking(new DbExpectations() {{
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn, messageId);
+			oneOf(db).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 		}});
 
-		clientHelper.getMessageAsList(messageId);
+		clientHelper.getSmallMessageAsList(messageId);
 		context.assertIsSatisfied();
 	}
 

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseComponentImplTest.java

@@ -323,7 +323,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 
 		try {
 			db.transaction(false, transaction ->
-					db.generateBatch(transaction, contactId, 123, 456));
+					db.generateBatch(transaction, contactId, 123, 456, true));
 			fail();
 		} catch (NoSuchContactException expected) {
 			// Expected
@@ -331,7 +331,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 
 		try {
 			db.transaction(false, transaction ->
-					db.generateOffer(transaction, contactId, 123, 456));
+					db.generateOffer(transaction, contactId, 123, 456, true));
 			fail();
 		} catch (NoSuchContactException expected) {
 			// Expected
@@ -624,7 +624,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 
 		try {
 			db.transaction(false, transaction ->
-					db.getMessage(transaction, messageId));
+					db.getSmallMessage(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
 			// Expected
@@ -865,14 +865,14 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			will(returnValue(txn));
 			oneOf(database).containsContact(txn, contactId);
 			will(returnValue(true));
-			oneOf(database).getMessagesToSend(txn, contactId,
+			oneOf(database).getSmallMessagesToSend(txn, contactId,
 					MAX_MESSAGE_LENGTH * 2, maxLatency);
 			will(returnValue(ids));
-			oneOf(database).getMessage(txn, messageId);
+			oneOf(database).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 			oneOf(database).updateExpiryTimeAndEta(txn, contactId, messageId,
 					maxLatency);
-			oneOf(database).getMessage(txn, messageId1);
+			oneOf(database).getSmallMessage(txn, messageId1);
 			will(returnValue(message1));
 			oneOf(database).updateExpiryTimeAndEta(txn, contactId, messageId1,
 					maxLatency);
@@ -885,7 +885,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 
 		db.transaction(false, transaction ->
 				assertEquals(messages, db.generateBatch(transaction, contactId,
-						MAX_MESSAGE_LENGTH * 2, maxLatency)));
+						MAX_MESSAGE_LENGTH * 2, maxLatency, true)));
 	}
 
 	@Test
@@ -897,7 +897,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			will(returnValue(txn));
 			oneOf(database).containsContact(txn, contactId);
 			will(returnValue(true));
-			oneOf(database).getMessagesToOffer(txn, contactId, 123, maxLatency);
+			oneOf(database).getSmallMessagesToOffer(txn, contactId, 123,
+					maxLatency);
 			will(returnValue(ids));
 			oneOf(database).updateExpiryTimeAndEta(txn, contactId, messageId,
 					maxLatency);
@@ -909,7 +910,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 				eventExecutor, shutdownManager);
 
 		db.transaction(false, transaction -> {
-			Offer o = db.generateOffer(transaction, contactId, 123, maxLatency);
+			Offer o = db.generateOffer(transaction, contactId, 123, maxLatency,
+					true);
 			assertNotNull(o);
 			assertEquals(ids, o.getMessageIds());
 		});
@@ -951,11 +953,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			oneOf(database).getRequestedMessagesToSend(txn, contactId,
 					MAX_MESSAGE_LENGTH * 2, maxLatency);
 			will(returnValue(ids));
-			oneOf(database).getMessage(txn, messageId);
+			oneOf(database).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 			oneOf(database).updateExpiryTimeAndEta(txn, contactId, messageId,
 					maxLatency);
-			oneOf(database).getMessage(txn, messageId1);
+			oneOf(database).getSmallMessage(txn, messageId1);
 			will(returnValue(message1));
 			oneOf(database).updateExpiryTimeAndEta(txn, contactId, messageId1,
 					maxLatency);

bramble-core/src/test/java/org/briarproject/bramble/db/DatabasePerformanceComparisonTest.java

@@ -3,11 +3,9 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.system.SystemClock;
 import org.briarproject.bramble.test.TestDatabaseConfig;
-import org.briarproject.bramble.test.TestMessageFactory;
 import org.briarproject.bramble.test.UTest;
 
 import java.io.IOException;
@@ -32,8 +30,7 @@ public abstract class DatabasePerformanceComparisonTest
 	private SecretKey databaseKey = getSecretKey();
 
 	abstract Database<Connection> createDatabase(boolean conditionA,
-			DatabaseConfig databaseConfig, MessageFactory messageFactory,
-			Clock clock);
+			DatabaseConfig databaseConfig, Clock clock);
 
 	@Override
 	protected void benchmark(String name,
@@ -76,8 +73,7 @@ public abstract class DatabasePerformanceComparisonTest
 	private Database<Connection> openDatabase(boolean conditionA)
 			throws DbException {
 		Database<Connection> db = createDatabase(conditionA,
-				new TestDatabaseConfig(testDir), new TestMessageFactory(),
-				new SystemClock());
+				new TestDatabaseConfig(testDir), new SystemClock());
 		db.open(databaseKey, null);
 		return db;
 	}

bramble-core/src/test/java/org/briarproject/bramble/db/DatabasePerformanceTest.java

@@ -507,11 +507,11 @@ public abstract class DatabasePerformanceTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testGetMessage() throws Exception {
-		String name = "getMessage(T, MessageId)";
+	public void testGetSmallMessage() throws Exception {
+		String name = "getSmallMessage(T, MessageId)";
 		benchmark(name, db -> {
 			Connection txn = db.startTransaction();
-			db.getMessage(txn, pickRandom(messages).getId());
+			db.getSmallMessage(txn, pickRandom(messages).getId());
 			db.commitTransaction(txn);
 		});
 	}

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseTraceTest.java

@@ -3,11 +3,9 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.system.SystemClock;
 import org.briarproject.bramble.test.TestDatabaseConfig;
-import org.briarproject.bramble.test.TestMessageFactory;
 import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
@@ -26,7 +24,7 @@ public abstract class DatabaseTraceTest extends DatabasePerformanceTest {
 	private SecretKey databaseKey = getSecretKey();
 
 	abstract Database<Connection> createDatabase(DatabaseConfig databaseConfig,
-			MessageFactory messageFactory, Clock clock);
+			Clock clock);
 
 	@Nullable
 	protected abstract File getTraceFile();
@@ -48,8 +46,7 @@ public abstract class DatabaseTraceTest extends DatabasePerformanceTest {
 
 	private Database<Connection> openDatabase() throws DbException {
 		Database<Connection> db = createDatabase(
-				new TestDatabaseConfig(testDir), new TestMessageFactory(),
-				new SystemClock());
+				new TestDatabaseConfig(testDir), new SystemClock());
 		db.open(databaseKey, null);
 		return db;
 	}

bramble-core/src/test/java/org/briarproject/bramble/db/H2DatabasePerformanceTest.java

@@ -16,6 +16,6 @@ public class H2DatabasePerformanceTest extends SingleDatabasePerformanceTest {
 	@Override
 	protected JdbcDatabase createDatabase(DatabaseConfig config,
 			MessageFactory messageFactory, Clock clock) {
-		return new H2Database(config, messageFactory, clock);
+		return new H2Database(config, clock);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/H2DatabaseTest.java

@@ -9,6 +9,6 @@ public class H2DatabaseTest extends JdbcDatabaseTest {
 	@Override
 	protected JdbcDatabase createDatabase(DatabaseConfig config,
 			MessageFactory messageFactory, Clock clock) {
-		return new H2Database(config, messageFactory, clock);
+		return new H2Database(config, clock);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/H2DatabaseTraceTest.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.db.DatabaseConfig;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.junit.Ignore;
 
@@ -15,8 +14,8 @@ public class H2DatabaseTraceTest extends DatabaseTraceTest {
 
 	@Override
 	Database<Connection> createDatabase(DatabaseConfig databaseConfig,
-			MessageFactory messageFactory, Clock clock) {
-		return new H2Database(databaseConfig, messageFactory, clock) {
+			Clock clock) {
+		return new H2Database(databaseConfig, clock) {
 			@Override
 			@Nonnull
 			String getUrl() {

bramble-core/src/test/java/org/briarproject/bramble/db/H2HyperSqlDatabasePerformanceComparisonTest.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.db.DatabaseConfig;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.junit.Ignore;
 
@@ -13,11 +12,11 @@ public class H2HyperSqlDatabasePerformanceComparisonTest
 
 	@Override
 	Database<Connection> createDatabase(boolean conditionA,
-			DatabaseConfig databaseConfig, MessageFactory messageFactory,
+			DatabaseConfig databaseConfig,
 			Clock clock) {
 		if (conditionA)
-			return new H2Database(databaseConfig, messageFactory, clock);
-		else return new HyperSqlDatabase(databaseConfig, messageFactory, clock);
+			return new H2Database(databaseConfig, clock);
+		else return new HyperSqlDatabase(databaseConfig, clock);
 	}
 
 	@Override

bramble-core/src/test/java/org/briarproject/bramble/db/H2MigrationTest.java

@@ -11,7 +11,7 @@ public class H2MigrationTest extends DatabaseMigrationTest {
 	@Override
 	Database<Connection> createDatabase(
 			List<Migration<Connection>> migrations) {
-		return new H2Database(config, messageFactory, clock) {
+		return new H2Database(config, clock) {
 			@Override
 			List<Migration<Connection>> getMigrations() {
 				return migrations;

bramble-core/src/test/java/org/briarproject/bramble/db/H2SelfDatabasePerformanceComparisonTest.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.db.DatabaseConfig;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.junit.Ignore;
 
@@ -18,9 +17,9 @@ public class H2SelfDatabasePerformanceComparisonTest
 
 	@Override
 	Database<Connection> createDatabase(boolean conditionA,
-			DatabaseConfig databaseConfig, MessageFactory messageFactory,
+			DatabaseConfig databaseConfig,
 			Clock clock) {
-		return new H2Database(databaseConfig, messageFactory, clock);
+		return new H2Database(databaseConfig, clock);
 	}
 
 	@Override

bramble-core/src/test/java/org/briarproject/bramble/db/H2SleepDatabasePerformanceComparisonTest.java

@@ -3,7 +3,6 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.junit.Ignore;
 
@@ -20,12 +19,11 @@ public class H2SleepDatabasePerformanceComparisonTest
 
 	@Override
 	Database<Connection> createDatabase(boolean conditionA,
-			DatabaseConfig databaseConfig, MessageFactory messageFactory,
-			Clock clock) {
+			DatabaseConfig databaseConfig, Clock clock) {
 		if (conditionA) {
-			return new H2Database(databaseConfig, messageFactory, clock);
+			return new H2Database(databaseConfig, clock);
 		} else {
-			return new H2Database(databaseConfig, messageFactory, clock) {
+			return new H2Database(databaseConfig, clock) {
 				@Override
 				@NotNullByDefault
 				public void commitTransaction(Connection txn)

bramble-core/src/test/java/org/briarproject/bramble/db/HyperSqlDatabasePerformanceTest.java

@@ -17,6 +17,6 @@ public class HyperSqlDatabasePerformanceTest
 	@Override
 	protected JdbcDatabase createDatabase(DatabaseConfig config,
 			MessageFactory messageFactory, Clock clock) {
-		return new HyperSqlDatabase(config, messageFactory, clock);
+		return new HyperSqlDatabase(config, clock);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/HyperSqlDatabaseTest.java

@@ -9,6 +9,6 @@ public class HyperSqlDatabaseTest extends JdbcDatabaseTest {
 	@Override
 	protected JdbcDatabase createDatabase(DatabaseConfig config,
 			MessageFactory messageFactory, Clock clock) {
-		return new HyperSqlDatabase(config, messageFactory ,clock);
+		return new HyperSqlDatabase(config, clock);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/HyperSqlMigrationTest.java

@@ -11,7 +11,7 @@ public class HyperSqlMigrationTest extends DatabaseMigrationTest {
 	@Override
 	Database<Connection> createDatabase(
 			List<Migration<Connection>> migrations) {
-		return new HyperSqlDatabase(config, messageFactory, clock) {
+		return new HyperSqlDatabase(config, clock) {
 			@Override
 			List<Migration<Connection>> getMigrations() {
 				return migrations;

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -166,7 +166,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(db.containsGroup(txn, groupId));
 		assertTrue(db.containsMessage(txn, messageId));
 		assertArrayEquals(message.getBody(),
-				db.getMessage(txn, messageId).getBody());
+				db.getSmallMessage(txn, messageId).getBody());
 
 		// Delete the records
 		db.removeMessage(txn, messageId);
@@ -1929,7 +1929,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(singletonList(messageId), ids);
 
 		// The message should be available
-		Message m = db.getMessage(txn, messageId);
+		Message m = db.getSmallMessage(txn, messageId);
 		assertEquals(messageId, m.getId());
 		assertEquals(groupId, m.getGroupId());
 		assertEquals(message.getTimestamp(), m.getTimestamp());
@@ -1949,7 +1949,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Requesting the message should throw an exception
 		try {
-			db.getMessage(txn, messageId);
+			db.getSmallMessage(txn, messageId);
 			fail();
 		} catch (MessageDeletedException expected) {
 			// Expected
@@ -2087,7 +2087,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		Connection txn = db.startTransaction();
 		try {
 			// Ask for a nonexistent message - an exception should be thrown
-			db.getMessage(txn, messageId);
+			db.getSmallMessage(txn, messageId);
 			fail();
 		} catch (DbException expected) {
 			// It should be possible to abort the transaction without error

bramble-core/src/test/java/org/briarproject/bramble/properties/TransportPropertyManagerImplTest.java

@@ -402,7 +402,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, fooUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, fooUpdateId);
 			will(returnValue(fooUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
@@ -469,7 +469,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup2.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, fooUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, fooUpdateId);
 			will(returnValue(fooUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
@@ -524,7 +524,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, updateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, updateId);
 			will(returnValue(update));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
@@ -562,7 +562,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, updateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, updateId);
 			will(returnValue(update));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
@@ -693,7 +693,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(localGroupMessageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localGroupUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localGroupUpdateId);
 			will(returnValue(oldUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					oldPropertiesDict);
@@ -758,7 +758,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(localGroupMessageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localGroupUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localGroupUpdateId);
 			will(returnValue(oldUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					oldPropertiesDict);
@@ -817,12 +817,12 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 					localGroup.getId());
 			will(returnValue(messageMetadata));
 			// Retrieve and parse the latest local properties
-			oneOf(clientHelper).getMessageAsList(txn, fooVersion999);
+			oneOf(clientHelper).getSmallMessageAsList(txn, fooVersion999);
 			will(returnValue(fooUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
 			will(returnValue(fooProperties));
-			oneOf(clientHelper).getMessageAsList(txn, barVersion3);
+			oneOf(clientHelper).getSmallMessageAsList(txn, barVersion3);
 			will(returnValue(barUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					barPropertiesDict);

bramble-core/src/test/java/org/briarproject/bramble/sync/SimplexOutgoingSessionTest.java

@@ -64,7 +64,7 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 			oneOf(db).transactionWithNullableResult(with(false),
 					withNullableDbCallable(noMsgTxn));
 			oneOf(db).generateBatch(with(noMsgTxn), with(contactId),
-					with(any(int.class)), with(MAX_LATENCY));
+					with(any(int.class)), with(MAX_LATENCY), with(true));
 			will(returnValue(null));
 			// Send the end of stream marker
 			oneOf(streamWriter).sendEndOfStream();
@@ -101,7 +101,7 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 			oneOf(db).transactionWithNullableResult(with(false),
 					withNullableDbCallable(msgTxn));
 			oneOf(db).generateBatch(with(msgTxn), with(contactId),
-					with(any(int.class)), with(MAX_LATENCY));
+					with(any(int.class)), with(MAX_LATENCY), with(true));
 			will(returnValue(singletonList(message)));
 			oneOf(recordWriter).writeMessage(message);
 			// No more acks
@@ -113,7 +113,7 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 			oneOf(db).transactionWithNullableResult(with(false),
 					withNullableDbCallable(noMsgTxn));
 			oneOf(db).generateBatch(with(noMsgTxn), with(contactId),
-					with(any(int.class)), with(MAX_LATENCY));
+					with(any(int.class)), with(MAX_LATENCY), with(true));
 			will(returnValue(null));
 			// Send the end of stream marker
 			oneOf(streamWriter).sendEndOfStream();

bramble-core/src/test/java/org/briarproject/bramble/sync/validation/ValidationManagerImplTest.java

@@ -99,7 +99,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		context.checking(new DbExpectations() {{
 			// Load the first raw message and group
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn, messageId);
+			oneOf(db).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
@@ -118,7 +118,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(emptyMap()));
 			// Load the second raw message and group
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
-			oneOf(db).getMessage(txn2, messageId1);
+			oneOf(db).getSmallMessage(txn2, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn2, groupId);
 			will(returnValue(group));
@@ -159,7 +159,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn, messageId);
 			will(returnValue(singletonMap(messageId1, DELIVERED)));
 			// Get the message and its metadata to deliver
-			oneOf(db).getMessage(txn, messageId);
+			oneOf(db).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
@@ -179,7 +179,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn1, messageId2);
 			will(returnValue(singletonMap(messageId1, DELIVERED)));
 			// Get the dependent and its metadata to deliver
-			oneOf(db).getMessage(txn1, messageId2);
+			oneOf(db).getSmallMessage(txn1, messageId2);
 			will(returnValue(message2));
 			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
@@ -276,11 +276,11 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		context.checking(new DbExpectations() {{
 			// Load the first raw message - *gasp* it's gone!
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn, messageId);
+			oneOf(db).getSmallMessage(txn, messageId);
 			will(throwException(new NoSuchMessageException()));
 			// Load the second raw message and group
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getMessage(txn1, messageId1);
+			oneOf(db).getSmallMessage(txn1, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
@@ -317,14 +317,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		context.checking(new DbExpectations() {{
 			// Load the first raw message
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn, messageId);
+			oneOf(db).getSmallMessage(txn, messageId);
 			will(returnValue(message));
 			// Load the group - *gasp* it's gone!
 			oneOf(db).getGroup(txn, groupId);
 			will(throwException(new NoSuchGroupException()));
 			// Load the second raw message and group
 			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getMessage(txn1, messageId1);
+			oneOf(db).getSmallMessage(txn1, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
@@ -614,7 +614,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn2, messageId1);
 			will(returnValue(singletonMap(messageId, DELIVERED)));
 			// Get message 1 and its metadata
-			oneOf(db).getMessage(txn2, messageId1);
+			oneOf(db).getSmallMessage(txn2, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn2, groupId);
 			will(returnValue(group));
@@ -634,7 +634,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn3, messageId2);
 			will(returnValue(singletonMap(messageId, DELIVERED)));
 			// Get message 2 and its metadata
-			oneOf(db).getMessage(txn3, messageId2);
+			oneOf(db).getSmallMessage(txn3, messageId2);
 			will(returnValue(message2));
 			oneOf(db).getGroup(txn3, groupId);
 			will(returnValue(group));
@@ -654,7 +654,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn4, messageId3);
 			will(returnValue(twoDependencies));
 			// Get message 3 and its metadata
-			oneOf(db).getMessage(txn4, messageId3);
+			oneOf(db).getSmallMessage(txn4, messageId3);
 			will(returnValue(message3));
 			oneOf(db).getGroup(txn4, groupId);
 			will(returnValue(group));
@@ -677,7 +677,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).getMessageDependencies(txn6, messageId4);
 			will(returnValue(singletonMap(messageId3, DELIVERED)));
 			// Get message 4 and its metadata
-			oneOf(db).getMessage(txn6, messageId4);
+			oneOf(db).getSmallMessage(txn6, messageId4);
 			will(returnValue(message4));
 			oneOf(db).getGroup(txn6, groupId);
 			will(returnValue(group));

bramble-core/src/test/java/org/briarproject/bramble/versioning/ClientVersioningManagerImplTest.java

@@ -38,6 +38,7 @@ import static org.briarproject.bramble.test.TestUtils.getContact;
 import static org.briarproject.bramble.test.TestUtils.getGroup;
 import static org.briarproject.bramble.test.TestUtils.getMessage;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.versioning.ClientVersioningConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_LOCAL;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_UPDATE_VERSION;
 import static org.junit.Assert.assertEquals;
@@ -59,6 +60,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 	private final ClientId clientId = getClientId();
 	private final long now = System.currentTimeMillis();
 	private final Transaction txn = new Transaction(null, false);
+	private final BdfDictionary groupMeta = BdfDictionary.of(
+			new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 	private ClientVersioningManagerImpl createInstance() {
 		context.checking(new Expectations() {{
@@ -120,8 +123,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).addGroup(txn, contactGroup);
 			oneOf(db).setGroupVisibility(txn, contact.getId(),
 					contactGroup.getId(), SHARED);
-			oneOf(clientHelper).setContactId(txn, contactGroup.getId(),
-					contact.getId());
+			oneOf(clientHelper).mergeGroupMetadata(txn, contactGroup.getId(),
+					groupMeta);
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(now));
 			oneOf(clientHelper).createMessage(contactGroup.getId(), now,
@@ -181,7 +184,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					contactGroup.getId());
 			will(returnValue(singletonMap(localUpdateId, localUpdateMeta)));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
 			// Latest local update is up-to-date, no visibilities have changed
 		}});
@@ -203,7 +206,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(localVersionsId)));
-			oneOf(clientHelper).getMessageAsList(txn, localVersionsId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localVersionsId);
 			will(returnValue(localVersionsBody));
 			// Client versions are up-to-date
 		}});
@@ -245,7 +248,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(oldLocalVersionsId)));
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalVersionsId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalVersionsId);
 			will(returnValue(oldLocalVersionsBody));
 			// Delete the old client versions
 			oneOf(db).removeMessage(txn, oldLocalVersionsId);
@@ -269,7 +272,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(singletonMap(oldLocalUpdateId,
 					oldLocalUpdateMeta)));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
 			// Delete the latest local update
 			oneOf(db).deleteMessage(txn, oldLocalUpdateId);
@@ -341,7 +344,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(oldLocalVersionsId)));
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalVersionsId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalVersionsId);
 			will(returnValue(oldLocalVersionsBody));
 			// Delete the old client versions
 			oneOf(db).removeMessage(txn, oldLocalVersionsId);
@@ -364,10 +367,10 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
 			// Load the latest remote update
-			oneOf(clientHelper).getMessageAsList(txn, oldRemoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldRemoteUpdateId);
 			will(returnValue(oldRemoteUpdateBody));
 			// Delete the latest local update
 			oneOf(db).deleteMessage(txn, oldLocalUpdateId);
@@ -448,17 +451,18 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
 			// Load the latest remote update
-			oneOf(clientHelper).getMessageAsList(txn, oldRemoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldRemoteUpdateId);
 			will(returnValue(oldRemoteUpdateBody));
 			// Delete the old remote update
 			oneOf(db).deleteMessage(txn, oldRemoteUpdateId);
 			oneOf(db).deleteMessageMetadata(txn, oldRemoteUpdateId);
 			// Get contact ID
-			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-			will(returnValue(contact.getId()));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(groupMeta));
 			// No states or visibilities have changed
 		}});
 
@@ -486,11 +490,12 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(singletonMap(oldLocalUpdateId,
 					oldLocalUpdateMeta)));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
-			// Get contact ID
-			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-			will(returnValue(contact.getId()));
+			// Get client ID
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(groupMeta));
 			// No states or visibilities have changed
 		}});
 
@@ -541,6 +546,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfDictionary newLocalUpdateMeta = BdfDictionary.of(
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
+		BdfDictionary groupMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 		context.checking(new Expectations() {{
 			oneOf(clientHelper).toList(newRemoteUpdate);
@@ -550,10 +557,10 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
 			// Load the latest remote update
-			oneOf(clientHelper).getMessageAsList(txn, oldRemoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldRemoteUpdateId);
 			will(returnValue(oldRemoteUpdateBody));
 			// Delete the old remote update
 			oneOf(db).deleteMessage(txn, oldRemoteUpdateId);
@@ -570,8 +577,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
 					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
-			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-			will(returnValue(contact.getId()));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(groupMeta));
 			oneOf(db).getContact(txn, contact.getId());
 			will(returnValue(contact));
 			oneOf(hook).onClientVisibilityChanging(txn, contact, visibility);
@@ -611,6 +619,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfDictionary newLocalUpdateMeta = BdfDictionary.of(
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
+		BdfDictionary groupMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 		context.checking(new Expectations() {{
 			oneOf(clientHelper).toList(newRemoteUpdate);
@@ -620,10 +630,10 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
 			// Load the latest local update
-			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
 			// Load the latest remote update
-			oneOf(clientHelper).getMessageAsList(txn, oldRemoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, oldRemoteUpdateId);
 			will(returnValue(oldRemoteUpdateBody));
 			// Delete the old remote update
 			oneOf(db).deleteMessage(txn, oldRemoteUpdateId);
@@ -640,8 +650,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
 					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
-			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-			will(returnValue(contact.getId()));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(groupMeta));
 			oneOf(db).getContact(txn, contact.getId());
 			will(returnValue(contact));
 			oneOf(hook).onClientVisibilityChanging(txn, contact, INVISIBLE);
@@ -723,9 +734,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -758,9 +769,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -793,9 +804,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -828,9 +839,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -890,7 +901,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -922,7 +933,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 
@@ -954,7 +965,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(clientHelper).getMessageAsList(txn, remoteUpdateId);
+			oneOf(clientHelper).getSmallMessageAsList(txn, remoteUpdateId);
 			will(returnValue(remoteUpdateBody));
 		}});
 

bramble-java/build.gradle

@@ -16,7 +16,7 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.12@zip'
+	tor 'org.briarproject:tor:0.3.5.10@zip'
 	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

bramble-java/witness.gradle

@@ -24,7 +24,7 @@ dependencyVerification {
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
-        'org.briarproject:tor:0.3.5.12:tor-0.3.5.12.zip:2f542c4befd216f2226bf7c76e3b8b2d99af6f146a8cb28bf727f42014587006',
+        'org.briarproject:tor:0.3.5.10:tor-0.3.5.10.zip:7b387d3523ae8af289c23be59dc4c64ec5d3721385d7825a09705095e3318d5c',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

briar-android/build.gradle

@@ -93,12 +93,12 @@ dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
 	implementation project(':bramble-android')
 
-	implementation 'androidx.preference:preference:1.1.1'
-	implementation 'androidx.exifinterface:exifinterface:1.3.1'
-	implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
-	implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
-	implementation 'com.google.android.material:material:1.2.1'
-	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc03'
+	implementation 'androidx.preference:preference:1.1.0'
+	implementation 'androidx.exifinterface:exifinterface:1.0.0'
+	implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
+	implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+	implementation 'com.google.android.material:material:1.1.0-beta01'
+	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc01'
 
 	implementation 'ch.acra:acra:4.11'
 	implementation 'info.guardianproject.panic:panic:1.0'
@@ -106,7 +106,7 @@ dependencies {
 	implementation 'de.hdodenhof:circleimageview:3.0.1'
 	implementation 'com.google.zxing:core:3.3.3'  // newer version need minSdk 24
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:3.0.0'
-	implementation 'com.vanniktech:emoji-google:0.6.0' // newer versions need minSdk 21
+	implementation 'com.vanniktech:emoji-google:0.6.0'
 	implementation 'com.github.kobakei:MaterialFabSpeedDial:1.2.1'
 	implementation 'com.github.chrisbanes:PhotoView:2.3.0'
 	def glideVersion = '4.10.0'
@@ -120,13 +120,13 @@ dependencies {
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
-	def espressoVersion = '3.3.0'
+	def espressoVersion = '3.2.0'
 	def jmockVersion = '2.8.2'
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
-	testImplementation 'androidx.test:runner:1.3.0'
-	testImplementation 'androidx.test.ext:junit:1.1.2'
-	testImplementation 'androidx.fragment:fragment-testing:1.2.5'
+	testImplementation 'androidx.test:runner:1.2.0'
+	testImplementation 'androidx.test.ext:junit:1.1.1'
+	testImplementation 'androidx.fragment:fragment-testing:1.1.0'
 	testImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
 	testImplementation 'org.robolectric:robolectric:4.3.1'
 	testImplementation 'org.mockito:mockito-core:3.1.0'
@@ -136,7 +136,7 @@ dependencies {
 	testImplementation "org.jmock:jmock-legacy:$jmockVersion"
 
 	androidTestImplementation project(path: ':bramble-api', configuration: 'testOutput')
-	androidTestImplementation 'androidx.test.ext:junit:1.1.2'
+	androidTestImplementation 'androidx.test.ext:junit:1.1.1'
 	androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
 	androidTestImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
 	androidTestImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"

briar-android/proguard-rules.txt

@@ -37,6 +37,3 @@
 
 # Glide
 -dontwarn com.bumptech.glide.load.engine.cache.DiskLruCacheWrapper
-
-# Dependency injection annotations, needed for UI tests on older API levels
--keep class javax.inject.**

briar-android/src/main/AndroidManifest.xml

@@ -141,16 +141,6 @@
 				android:value="org.briarproject.briar.android.conversation.ConversationActivity" />
 		</activity>
 
-		<activity
-			android:name=".android.conversation.ConversationSettingsActivity"
-			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity"
-			android:label="@string/disappearing_messages_title"
-			android:theme="@style/BriarTheme">
-			<meta-data
-				android:name="android.support.PARENT_ACTIVITY"
-				android:value="org.briarproject.briar.android.conversation.ConversationActivity" />
-		</activity>
-
 		<activity
 			android:name="org.briarproject.briar.android.privategroup.creation.CreateGroupActivity"
 			android:label="@string/groups_create_group_title"

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -14,7 +14,6 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
@@ -40,7 +39,6 @@ import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
 import org.briarproject.briar.api.android.LockManager;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
-import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogPostFactory;
 import org.briarproject.briar.api.blog.BlogSharingManager;
@@ -171,10 +169,6 @@ public interface AndroidComponent
 
 	AndroidWakeLockManager wakeLockManager();
 
-	TransactionManager transactionManager();
-
-	AutoDeleteManager autoDeleteManager();
-
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

briar-android/src/main/java/org/briarproject/briar/android/account/AuthorNameFragment.java

@@ -17,6 +17,7 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 
 import javax.annotation.Nullable;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.toUtf8;
 import static org.briarproject.briar.android.util.UiUtils.setError;
@@ -44,7 +45,7 @@ public class AuthorNameFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireActivity().setTitle(getString(R.string.setup_title));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_title));
 		View v = inflater.inflate(R.layout.fragment_setup_author_name,
 				container, false);
 		authorNameWrapper = v.findViewById(R.id.nickname_entry_wrapper);

briar-android/src/main/java/org/briarproject/briar/android/account/DozeFragment.java

@@ -20,6 +20,7 @@ import androidx.annotation.Nullable;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
@@ -49,10 +50,10 @@ public class DozeFragment extends SetupFragment
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireActivity().setTitle(getString(R.string.setup_doze_title));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_doze_title));
 		setHasOptionsMenu(false);
 		View v = inflater.inflate(R.layout.fragment_setup_doze, container,
-				false);
+						false);
 		dozeView = v.findViewById(R.id.dozeView);
 		dozeView.setOnCheckedChangedListener(this);
 		huaweiView = v.findViewById(R.id.huaweiView);
@@ -77,8 +78,7 @@ public class DozeFragment extends SetupFragment
 	}
 
 	@Override
-	public void onActivityResult(int request, int result,
-			@Nullable Intent data) {
+	public void onActivityResult(int request, int result, Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_DOZE_WHITELISTING) {
 			if (!dozeView.needsToBeShown() || secondAttempt) {
@@ -92,7 +92,11 @@ public class DozeFragment extends SetupFragment
 
 	@Override
 	public void onCheckedChanged() {
-		next.setEnabled(dozeView.isChecked() && huaweiView.isChecked());
+		if (dozeView.isChecked() && huaweiView.isChecked()) {
+			next.setEnabled(true);
+		} else {
+			next.setEnabled(false);
+		}
 	}
 
 	@SuppressLint("BatteryLife")

briar-android/src/main/java/org/briarproject/briar/android/account/SetPasswordFragment.java

@@ -24,6 +24,7 @@ import static android.content.Context.INPUT_METHOD_SERVICE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 import static org.briarproject.briar.android.util.UiUtils.setError;
 
@@ -54,7 +55,7 @@ public class SetPasswordFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireActivity().setTitle(getString(R.string.setup_password_intro));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_password_intro));
 		View v = inflater.inflate(R.layout.fragment_setup_password, container,
 						false);
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -28,8 +28,6 @@ import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
-import org.briarproject.briar.android.conversation.ConversationSettingsActivity;
-import org.briarproject.briar.android.conversation.ConversationSettingsFragment;
 import org.briarproject.briar.android.conversation.ImageActivity;
 import org.briarproject.briar.android.conversation.ImageFragment;
 import org.briarproject.briar.android.forum.CreateForumActivity;
@@ -186,8 +184,6 @@ public interface ActivityComponent {
 
 	void inject(PendingContactListActivity activity);
 
-	void inject(ConversationSettingsActivity activity);
-
 	// Fragments
 
 	void inject(AuthorNameFragment fragment);
@@ -238,6 +234,4 @@ public interface ActivityComponent {
 
 	void inject(ImageFragment imageFragment);
 
-	void inject(ConversationSettingsFragment conversationSettingsFragment);
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -25,6 +25,7 @@ import androidx.annotation.UiThread;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
@@ -54,7 +55,7 @@ abstract class BasePostFragment extends BaseFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		// retrieve MessageId of blog post from arguments
-		byte[] p = requireArguments().getByteArray(POST_ID);
+		byte[] p = requireNonNull(getArguments()).getByteArray(POST_ID);
 		if (p == null) throw new IllegalStateException("No post ID in args");
 		postId = new MessageId(p);
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -46,6 +46,7 @@ import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.widget.Toast.LENGTH_SHORT;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
@@ -96,14 +97,14 @@ public class BlogFragment extends BaseFragment
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		groupId = new GroupId(b);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(requireActivity(), this,
+		adapter = new BlogPostAdapter(requireNonNull(getActivity()), this,
 				getFragmentManager());
 		list = v.findViewById(R.id.postList);
 		layoutManager = new LinearLayoutManager(getActivity());
@@ -195,8 +196,7 @@ public class BlogFragment extends BaseFragment
 	}
 
 	@Override
-	public void onActivityResult(int request, int result,
-			@Nullable Intent data) {
+	public void onActivityResult(int request, int result, Intent data) {
 		super.onActivityResult(request, result, data);
 
 		if (request == REQUEST_WRITE_BLOG_POST && result == RESULT_OK) {

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -35,6 +35,7 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
@@ -78,7 +79,7 @@ public class FeedFragment extends BaseFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireActivity().setTitle(R.string.blogs_button);
+		requireNonNull(getActivity()).setTitle(R.string.blogs_button);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
@@ -102,8 +103,7 @@ public class FeedFragment extends BaseFragment implements
 	}
 
 	@Override
-	public void onActivityResult(int requestCode, int resultCode,
-			@Nullable Intent data) {
+	public void onActivityResult(int requestCode, int resultCode, Intent data) {
 		super.onActivityResult(requestCode, resultCode, data);
 
 		// The BlogPostAddedEvent arrives when the controller is not listening

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -18,6 +18,7 @@ import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @UiThread
@@ -53,7 +54,7 @@ public class FeedPostFragment extends BasePostFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		blogId = new GroupId(b);

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -74,7 +74,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		GroupId blogId =
 				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
 		MessageId postId =

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -62,6 +62,7 @@ import static android.os.Build.VERSION.SDK_INT;
 import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static androidx.core.view.ViewCompat.getTransitionName;
 import static com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -121,7 +122,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireActivity().setTitle(R.string.contact_list_button);
+		requireNonNull(getActivity()).setTitle(R.string.contact_list_button);
 
 		View contentView = inflater.inflate(R.layout.fragment_contact_list,
 				container, false);
@@ -273,8 +274,8 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 			removeItem(((ContactRemovedEvent) e).getContactId());
 		} else if (e instanceof ConversationMessageReceivedEvent) {
 			LOG.info("Conversation message received, updating item");
-			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent<?>) e;
+			ConversationMessageReceivedEvent p =
+					(ConversationMessageReceivedEvent) e;
 			ConversationMessageHeader h = p.getMessageHeader();
 			updateItem(p.getContactId(), h);
 		} else if (e instanceof PendingContactAddedEvent ||
@@ -316,7 +317,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 	@UiThread
 	private void showSnackBar() {
 		if (snackbar != null) return;
-		View v = requireView();
+		View v = requireNonNull(getView());
 		int stringRes = R.string.pending_contact_requests_snackbar;
 		snackbar = new BriarSnackbarBuilder()
 				.setAction(R.string.show, view -> showPendingContactList())

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/LinkExchangeFragment.java

@@ -33,6 +33,7 @@ import androidx.lifecycle.ViewModelProviders;
 
 import static android.content.Context.CLIPBOARD_SERVICE;
 import static android.widget.Toast.LENGTH_SHORT;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.contact.HandshakeLinkConstants.LINK_REGEX;
 import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 
@@ -82,8 +83,8 @@ public class LinkExchangeFragment extends BaseFragment
 			linkInput.setText(viewModel.getRemoteHandshakeLink());
 		}
 
-		clipboard = (ClipboardManager)
-				requireContext().getSystemService(CLIPBOARD_SERVICE);
+		clipboard = (ClipboardManager) requireNonNull(
+				getContext().getSystemService(CLIPBOARD_SERVICE));
 
 		Button pasteButton = v.findViewById(R.id.pasteButton);
 		pasteButton.setOnClickListener(view -> {
@@ -106,7 +107,7 @@ public class LinkExchangeFragment extends BaseFragment
 
 	@Override
 	public void onGlobalLayout() {
-		ScrollView scrollView = (ScrollView) requireView();
+		ScrollView scrollView = (ScrollView) requireNonNull(getView());
 		View layout = scrollView.getChildAt(0);
 		int scrollBy = layout.getHeight() - scrollView.getHeight();
 		if (scrollBy > 0) {
@@ -120,7 +121,7 @@ public class LinkExchangeFragment extends BaseFragment
 	}
 
 	private void onHandshakeLinkLoaded(String link) {
-		View v = requireView();
+		View v = requireNonNull(getView());
 
 		TextView linkView = v.findViewById(R.id.linkView);
 		linkView.setText(link);

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/NicknameFragment.java

@@ -31,7 +31,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.StringRes;
 import androidx.appcompat.app.AlertDialog.Builder;
-import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -118,8 +117,7 @@ public class NicknameFragment extends BaseFragment {
 		addButton.setVisibility(INVISIBLE);
 		progressBar.setVisibility(VISIBLE);
 
-		LifecycleOwner owner = getViewLifecycleOwner();
-		viewModel.getAddContactResult().observe(owner, result -> {
+		viewModel.getAddContactResult().observe(this, result -> {
 			if (result == null) return;
 			if (result.hasError())
 				handleException(name, requireNonNull(result.getException()));

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -26,6 +26,7 @@ import javax.annotation.Nullable;
 import androidx.annotation.CallSuper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.CONTACTS;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.getContactsFromIds;
@@ -54,7 +55,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No GroupId");
 		groupId = new GroupId(b);
@@ -73,7 +74,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 		list.setEmptyImage(R.drawable.ic_empty_state_contact_list);
 		list.setEmptyText(getString(R.string.no_contacts_selector));
 		list.setEmptyAction(getString(R.string.no_contacts_selector_action));
-		adapter = getAdapter(requireContext(), this);
+		adapter = getAdapter(requireNonNull(getContext()), this);
 		list.setAdapter(adapter);
 
 		// restore selected contacts if available

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -140,8 +140,6 @@ import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_ATTACHMENTS_PER_MESSAGE;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_PRIVATE_MESSAGE_TEXT_LENGTH;
-import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_IMAGES_AUTO_DELETE;
-import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_ONLY;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -275,11 +273,15 @@ public class ConversationActivity extends BriarActivity
 			ImagePreview imagePreview = findViewById(R.id.imagePreview);
 			sendController = new TextAttachmentController(textInputView,
 					imagePreview, this, viewModel);
-			observeOnce(viewModel.getPrivateMessageFormat(), this, format -> {
-				if (format != TEXT_ONLY) {
-					// TODO: remove cast when removing feature flag
-					((TextAttachmentController) sendController)
-							.setImagesSupported();
+			viewModel.hasImageSupport().observe(this, new Observer<Boolean>() {
+				@Override
+				public void onChanged(@Nullable Boolean hasSupport) {
+					if (hasSupport != null && hasSupport) {
+						// TODO: remove cast when removing feature flag
+						((TextAttachmentController) sendController)
+								.setImagesSupported();
+						viewModel.hasImageSupport().removeObserver(this);
+					}
 				}
 			});
 		} else {
@@ -382,12 +384,6 @@ public class ConversationActivity extends BriarActivity
 		// enable alias action if available
 		observeOnce(viewModel.getContact(), this, contact ->
 				menu.findItem(R.id.action_set_alias).setEnabled(true));
-		// show auto-delete timer setting only, if contacts supports it
-		observeOnce(viewModel.getPrivateMessageFormat(), this, format -> {
-			boolean visible = format == TEXT_IMAGES_AUTO_DELETE;
-			menu.findItem(R.id.action_conversation_settings)
-					.setVisible(visible);
-		});
 
 		return super.onCreateOptionsMenu(menu);
 	}
@@ -409,12 +405,6 @@ public class ConversationActivity extends BriarActivity
 				AliasDialogFragment.newInstance().show(
 						getSupportFragmentManager(), AliasDialogFragment.TAG);
 				return true;
-			case R.id.action_conversation_settings:
-				if (contactId == null) return false;
-				intent = new Intent(this, ConversationSettingsActivity.class);
-				intent.putExtra(CONTACT_ID, contactId.getInt());
-				startActivity(intent);
-				return true;
 			case R.id.action_delete_all_messages:
 				askToDeleteAllMessages();
 				return true;
@@ -667,8 +657,8 @@ public class ConversationActivity extends BriarActivity
 				supportFinishAfterTransition();
 			}
 		} else if (e instanceof ConversationMessageReceivedEvent) {
-			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent<?>) e;
+			ConversationMessageReceivedEvent p =
+					(ConversationMessageReceivedEvent) e;
 			if (p.getContactId().equals(contactId)) {
 				LOG.info("Message received, adding");
 				onNewConversationMessage(p.getMessageHeader());
@@ -766,10 +756,18 @@ public class ConversationActivity extends BriarActivity
 			List<AttachmentHeader> attachmentHeaders) {
 		if (isNullOrEmpty(text) && attachmentHeaders.isEmpty())
 			throw new AssertionError();
-		viewModel.sendMessage(text, attachmentHeaders);
+		long timestamp = System.currentTimeMillis();
+		timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
+		viewModel.sendMessage(text, attachmentHeaders, timestamp);
 		textInputView.clearText();
 	}
 
+	private long getMinTimestampForNewMessage() {
+		// Don't use an earlier timestamp than the newest message
+		ConversationItem item = adapter.getLastItem();
+		return item == null ? 0 : item.getTime() + 1;
+	}
+
 	private void onAddedPrivateMessage(@Nullable PrivateMessageHeader h) {
 		if (h == null) return;
 		addConversationItem(h.accept(visitor));
@@ -974,11 +972,13 @@ public class ConversationActivity extends BriarActivity
 			adapter.notifyItemChanged(position, item);
 		}
 		runOnDbThread(() -> {
+			long timestamp = System.currentTimeMillis();
+			timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
 			try {
 				switch (item.getRequestType()) {
 					case INTRODUCTION:
 						respondToIntroductionRequest(item.getSessionId(),
-								accept);
+								accept, timestamp);
 						break;
 					case FORUM:
 						respondToForumRequest(item.getSessionId(), accept);
@@ -1054,8 +1054,9 @@ public class ConversationActivity extends BriarActivity
 
 	@DatabaseExecutor
 	private void respondToIntroductionRequest(SessionId sessionId,
-			boolean accept) throws DbException {
-		introductionManager.respondToIntroduction(contactId, sessionId, accept);
+			boolean accept, long time) throws DbException {
+		introductionManager.respondToIntroduction(contactId, sessionId, time,
+				accept);
 	}
 
 	@DatabaseExecutor

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItem.java

@@ -22,7 +22,7 @@ abstract class ConversationItem {
 	protected String text;
 	private final MessageId id;
 	private final GroupId groupId;
-	private final long time, autoDeleteTimer;
+	private final long time;
 	private final boolean isIncoming;
 	private boolean read, sent, seen;
 
@@ -32,7 +32,6 @@ abstract class ConversationItem {
 		this.id = h.getId();
 		this.groupId = h.getGroupId();
 		this.time = h.getTimestamp();
-		this.autoDeleteTimer = h.getAutoDeleteTimer();
 		this.read = h.isRead();
 		this.sent = h.isSent();
 		this.seen = h.isSeen();
@@ -69,10 +68,6 @@ abstract class ConversationItem {
 		return time;
 	}
 
-	public long getAutoDeleteTimer() {
-		return autoDeleteTimer;
-	}
-
 	/**
 	 * Only useful for incoming messages.
 	 */

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItemViewHolder.java

@@ -12,11 +12,8 @@ import androidx.annotation.UiThread;
 import androidx.constraintlayout.widget.ConstraintLayout;
 import androidx.recyclerview.widget.RecyclerView.ViewHolder;
 
-import static android.view.View.GONE;
-import static android.view.View.VISIBLE;
 import static org.briarproject.bramble.util.StringUtils.trim;
 import static org.briarproject.briar.android.util.UiUtils.formatDate;
-import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 
 @UiThread
 @NotNullByDefault
@@ -29,7 +26,6 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 	private final OutItemViewHolder outViewHolder;
 	private final TextView text;
 	protected final TextView time;
-	private final View bomb;
 	@Nullable
 	private String itemKey = null;
 
@@ -42,7 +38,6 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 		layout = v.findViewById(R.id.layout);
 		text = v.findViewById(R.id.text);
 		time = v.findViewById(R.id.time);
-		bomb = v.findViewById(R.id.bomb);
 	}
 
 	@CallSuper
@@ -57,9 +52,6 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 		long timestamp = item.getTime();
 		time.setText(formatDate(time.getContext(), timestamp));
 
-		boolean showBomb = item.getAutoDeleteTimer() != NO_AUTO_DELETE_TIMER;
-		bomb.setVisibility(showBomb ? VISIBLE : GONE);
-
 		if (outViewHolder != null) outViewHolder.bind(item);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationSettingsActivity.java

@@ -1,80 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.content.Intent;
-import android.os.Bundle;
-import android.view.MenuItem;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.appcompat.app.ActionBar;
-import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
-
-import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class ConversationSettingsActivity extends BriarActivity implements
-		BaseFragmentListener {
-
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private ConversationViewModel viewModel;
-	private ContactId contactId;
-
-	@Override
-	public void onCreate(@Nullable Bundle bundle) {
-		super.onCreate(bundle);
-
-		Intent i = getIntent();
-		int id = i.getIntExtra(CONTACT_ID, -1);
-		if (id == -1) throw new IllegalStateException();
-		contactId = new ContactId(id);
-
-		ActionBar actionBar = getSupportActionBar();
-		if (actionBar != null) {
-			actionBar.setHomeButtonEnabled(true);
-			actionBar.setDisplayHomeAsUpEnabled(true);
-		}
-
-		setContentView(R.layout.activity_conversation_settings);
-
-		viewModel = ViewModelProviders.of(this, viewModelFactory)
-				.get(ConversationViewModel.class);
-	}
-
-	@Override
-	public void onResume() {
-		super.onResume();
-		// Trigger loading of contact data, noop if data was loaded already.
-		//
-		// We can only start loading data *after* we are sure
-		// the user has signed in. After sign-in, onCreate() isn't run again.
-		if (signedIn()) viewModel.setContactId(contactId);
-	}
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
-	}
-
-	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == android.R.id.home) {
-			onBackPressed();
-			return true;
-		}
-		return false;
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationSettingsFragment.java

@@ -1,158 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.content.Context;
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.Menu;
-import android.view.MenuInflater;
-import android.view.MenuItem;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.TextView;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.fragment.BaseFragment;
-import org.briarproject.briar.api.autodelete.AutoDeleteManager;
-
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.appcompat.widget.SwitchCompat;
-import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
-
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.briar.android.util.UiUtils.observeOnce;
-import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class ConversationSettingsFragment extends BaseFragment {
-
-	public static final String TAG =
-			ConversationSettingsFragment.class.getName();
-
-	private static final Logger LOG =
-			Logger.getLogger(ConversationSettingsFragment.class.getName());
-
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-	@Inject
-	@DatabaseExecutor
-	Executor dbExecutor;
-	@Inject
-	TransactionManager db;
-	@Inject
-	AutoDeleteManager autoDeleteManager;
-
-	private ConversationSettingsActivity listener;
-	private ConversationViewModel viewModel;
-	private SwitchCompat switchDisappearingMessages;
-	private volatile boolean disappearingMessages = false;
-
-	@Override
-	public String getUniqueTag() {
-		return TAG;
-	}
-
-	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
-		listener = (ConversationSettingsActivity) context;
-		listener.getActivityComponent().inject(this);
-	}
-
-	@Override
-	public void onCreate(@Nullable Bundle savedInstanceState) {
-		super.onCreate(savedInstanceState);
-		setHasOptionsMenu(true);
-	}
-
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		View contentView =
-				inflater.inflate(R.layout.fragment_conversation_settings,
-						container, false);
-
-		switchDisappearingMessages =
-				contentView.findViewById(R.id.switchDisappearingMessages);
-
-		switchDisappearingMessages
-				.setOnCheckedChangeListener((button, value) -> viewModel
-						.setAutoDeleteTimerEnabled(value));
-
-		TextView buttonLearnMore =
-				contentView.findViewById(R.id.buttonLearnMore);
-		buttonLearnMore.setOnClickListener(e -> showLearnMoreDialog());
-
-		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
-				.get(ConversationViewModel.class);
-
-		return contentView;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		switchDisappearingMessages.setEnabled(false);
-		loadSettings();
-	}
-
-	private void loadSettings() {
-		observeOnce(viewModel.getContact(), this, c -> {
-			dbExecutor.execute(() -> {
-				try {
-					db.transaction(false, txn -> {
-						long timer = autoDeleteManager
-								.getAutoDeleteTimer(txn, c.getId());
-						disappearingMessages = timer != NO_AUTO_DELETE_TIMER;
-					});
-					listener.runOnUiThreadUnlessDestroyed(
-							this::displaySettings);
-				} catch (DbException e) {
-					logException(LOG, WARNING, e);
-				}
-			});
-		});
-	}
-
-	private void displaySettings() {
-		switchDisappearingMessages.setChecked(disappearingMessages);
-		switchDisappearingMessages.setEnabled(true);
-	}
-
-	@Override
-	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
-		inflater.inflate(R.menu.help_action, menu);
-		super.onCreateOptionsMenu(menu, inflater);
-	}
-
-
-	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == R.id.action_help) {
-			showLearnMoreDialog();
-			return true;
-		}
-		return super.onOptionsItemSelected(item);
-	}
-
-	private void showLearnMoreDialog() {
-		ConversationSettingsLearnMoreDialog
-				dialog = new ConversationSettingsLearnMoreDialog();
-		dialog.show(requireActivity().getSupportFragmentManager(),
-				ConversationSettingsLearnMoreDialog.TAG);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationSettingsLearnMoreDialog.java

@@ -1,44 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.app.Dialog;
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.View;
-
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.briar.R;
-
-import androidx.appcompat.app.AlertDialog;
-import androidx.fragment.app.DialogFragment;
-import androidx.fragment.app.FragmentActivity;
-
-@MethodsNotNullByDefault
-public class ConversationSettingsLearnMoreDialog extends DialogFragment {
-
-	final static String TAG =
-			ConversationSettingsLearnMoreDialog.class.getName();
-
-	static ConversationSettingsLearnMoreDialog newInstance() {
-		return new ConversationSettingsLearnMoreDialog();
-	}
-
-	@Override
-	public Dialog onCreateDialog(Bundle savedInstanceState) {
-		FragmentActivity activity = requireActivity();
-
-		AlertDialog.Builder builder =
-				new AlertDialog.Builder(activity, R.style.BriarDialogTheme);
-
-		LayoutInflater inflater = LayoutInflater.from(getContext());
-		View view = inflater.inflate(
-				R.layout.fragment_conversation_settings_learn_more, null);
-		builder.setView(view);
-
-		builder.setTitle(R.string.disappearing_messages_title);
-		builder.setNeutralButton(R.string.ok, null);
-
-		return builder.create();
-	}
-
-
-}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java

@@ -10,7 +10,6 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
@@ -29,13 +28,10 @@ import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.util.UiUtils;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
-import org.briarproject.briar.api.autodelete.AutoDeleteManager;
-import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
-import org.briarproject.briar.api.messaging.PrivateMessageFormat;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
@@ -54,7 +50,6 @@ import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Transformations;
 
 import static java.util.Objects.requireNonNull;
-import static java.util.concurrent.TimeUnit.DAYS;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
@@ -62,15 +57,12 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
-import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
-import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_IMAGES;
-import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_ONLY;
 
 @NotNullByDefault
 public class ConversationViewModel extends AndroidViewModel
 		implements EventListener, AttachmentManager {
 
-	private static final Logger LOG =
+	private static Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
 
 	private static final String SHOW_ONBOARDING_IMAGE =
@@ -88,8 +80,6 @@ public class ConversationViewModel extends AndroidViewModel
 	private final PrivateMessageFactory privateMessageFactory;
 	private final AttachmentRetriever attachmentRetriever;
 	private final AttachmentCreator attachmentCreator;
-	private final AutoDeleteManager autoDeleteManager;
-	private final ConversationManager conversationManager;
 
 	@Nullable
 	private ContactId contactId = null;
@@ -99,7 +89,7 @@ public class ConversationViewModel extends AndroidViewModel
 	private final LiveData<String> contactName =
 			Transformations.map(contact, UiUtils::getContactDisplayName);
 	private final LiveData<GroupId> messagingGroupId;
-	private final MutableLiveData<PrivateMessageFormat> privateMessageFormat =
+	private final MutableLiveData<Boolean> imageSupport =
 			new MutableLiveData<>();
 	private final MutableLiveEvent<Boolean> showImageOnboarding =
 			new MutableLiveEvent<>();
@@ -122,9 +112,7 @@ public class ConversationViewModel extends AndroidViewModel
 			SettingsManager settingsManager,
 			PrivateMessageFactory privateMessageFactory,
 			AttachmentRetriever attachmentRetriever,
-			AttachmentCreator attachmentCreator,
-			AutoDeleteManager autoDeleteManager,
-			ConversationManager conversationManager) {
+			AttachmentCreator attachmentCreator) {
 		super(application);
 		this.dbExecutor = dbExecutor;
 		this.db = db;
@@ -135,8 +123,6 @@ public class ConversationViewModel extends AndroidViewModel
 		this.privateMessageFactory = privateMessageFactory;
 		this.attachmentRetriever = attachmentRetriever;
 		this.attachmentCreator = attachmentCreator;
-		this.autoDeleteManager = autoDeleteManager;
-		this.conversationManager = conversationManager;
 		messagingGroupId = Transformations
 				.map(contact, c -> messagingManager.getContactGroup(c).getId());
 		contactDeleted.setValue(false);
@@ -219,13 +205,16 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	@UiThread
-	void sendMessage(@Nullable String text, List<AttachmentHeader> headers) {
+	void sendMessage(@Nullable String text,
+			List<AttachmentHeader> headers, long timestamp) {
 		// messagingGroupId is loaded with the contact
 		observeForeverOnce(messagingGroupId, groupId -> {
 			requireNonNull(groupId);
-			observeForeverOnce(privateMessageFormat, format ->
-					storeMessage(requireNonNull(contactId), groupId, text,
-							headers, format));
+			observeForeverOnce(imageSupport, hasImageSupport -> {
+				requireNonNull(hasImageSupport);
+				createMessage(groupId, text, headers, timestamp,
+						hasImageSupport);
+			});
 		});
 	}
 
@@ -255,10 +244,10 @@ public class ConversationViewModel extends AndroidViewModel
 
 	@DatabaseExecutor
 	private void checkFeaturesAndOnboarding(ContactId c) throws DbException {
-		// check if images and auto-deletion are supported
-		PrivateMessageFormat format = db.transactionWithResult(true, txn ->
-				messagingManager.getContactMessageFormat(txn, c));
-		privateMessageFormat.postValue(format);
+		// check if images are supported
+		boolean imagesSupported = db.transactionWithResult(true, txn ->
+				messagingManager.contactSupportsImages(txn, c));
+		imageSupport.postValue(imagesSupported);
 
 		// check if introductions are supported
 		Collection<Contact> contacts = contactManager.getContacts();
@@ -267,7 +256,7 @@ public class ConversationViewModel extends AndroidViewModel
 
 		// we only show one onboarding dialog at a time
 		Settings settings = settingsManager.getSettings(SETTINGS_NAMESPACE);
-		if (format != TEXT_ONLY &&
+		if (imagesSupported &&
 				settings.getBoolean(SHOW_ONBOARDING_IMAGE, true)) {
 			onOnboardingShown(SHOW_ONBOARDING_IMAGE);
 			showImageOnboarding.postEvent(true);
@@ -285,67 +274,40 @@ public class ConversationViewModel extends AndroidViewModel
 		settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
 	}
 
-	private PrivateMessage createMessage(Transaction txn, ContactId c,
-			GroupId groupId, @Nullable String text,
-			List<AttachmentHeader> headers, PrivateMessageFormat format)
-			throws DbException {
-		long timestamp =
-				conversationManager.getTimestampForOutgoingMessage(txn, c);
+	@UiThread
+	private void createMessage(GroupId groupId, @Nullable String text,
+			List<AttachmentHeader> headers, long timestamp,
+			boolean hasImageSupport) {
 		try {
-			if (format == TEXT_ONLY) {
-				return privateMessageFactory.createLegacyPrivateMessage(
-						groupId, timestamp, requireNonNull(text));
-			} else if (format == TEXT_IMAGES) {
-				return privateMessageFactory.createPrivateMessage(groupId,
+			PrivateMessage pm;
+			if (hasImageSupport) {
+				pm = privateMessageFactory.createPrivateMessage(groupId,
 						timestamp, text, headers);
 			} else {
-				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
-						timestamp);
-				return privateMessageFactory.createPrivateMessage(groupId,
-						timestamp, text, headers, timer);
+				pm = privateMessageFactory.createLegacyPrivateMessage(
+						groupId, timestamp, requireNonNull(text));
 			}
+			storeMessage(pm);
 		} catch (FormatException e) {
 			throw new AssertionError(e);
 		}
 	}
 
 	@UiThread
-	private void storeMessage(ContactId c, GroupId groupId,
-			@Nullable String text, List<AttachmentHeader> headers,
-			PrivateMessageFormat format) {
+	private void storeMessage(PrivateMessage m) {
+		attachmentCreator.onAttachmentsSent(m.getMessage().getId());
 		dbExecutor.execute(() -> {
 			try {
-				db.transaction(false, txn -> {
-					long start = now();
-					PrivateMessage m = createMessage(txn, c, groupId, text,
-							headers, format);
-					messagingManager.addLocalMessage(txn, m);
-					logDuration(LOG, "Storing message", start);
-					Message message = m.getMessage();
-					PrivateMessageHeader h = new PrivateMessageHeader(
-							message.getId(), message.getGroupId(),
-							message.getTimestamp(), true, true, false, false,
-							m.hasText(), m.getAttachmentHeaders(),
-							m.getAutoDeleteTimer());
-					// TODO add text to cache when available here
-					MessageId id = message.getId();
-					txn.attach(() -> attachmentCreator.onAttachmentsSent(id));
-					addedHeader.postEvent(h);
-				});
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	void setAutoDeleteTimerEnabled(boolean enabled) {
-		final long timer = enabled ? DAYS.toMillis(7) : NO_AUTO_DELETE_TIMER;
-		// ContactId is set before menu gets inflated and UI interaction
-		final ContactId c = requireNonNull(contactId);
-		dbExecutor.execute(() -> {
-			try {
-				db.transaction(false, txn ->
-						autoDeleteManager.setAutoDeleteTimer(txn, c, timer));
+				long start = now();
+				messagingManager.addLocalMessage(m);
+				logDuration(LOG, "Storing message", start);
+				Message message = m.getMessage();
+				PrivateMessageHeader h = new PrivateMessageHeader(
+						message.getId(), message.getGroupId(),
+						message.getTimestamp(), true, true, false, false,
+						m.hasText(), m.getAttachmentHeaders());
+				// TODO add text to cache when available here
+				addedHeader.postEvent(h);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -368,8 +330,8 @@ public class ConversationViewModel extends AndroidViewModel
 		return contactName;
 	}
 
-	LiveData<PrivateMessageFormat> getPrivateMessageFormat() {
-		return privateMessageFormat;
+	LiveData<Boolean> hasImageSupport() {
+		return imageSupport;
 	}
 
 	LiveEvent<Boolean> showImageOnboarding() {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageFragment.java

@@ -27,7 +27,6 @@ import javax.inject.Inject;
 import androidx.annotation.DrawableRes;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
-import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -79,7 +78,7 @@ public class ImageFragment extends Fragment
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		attachment = requireNonNull(args.getParcelable(ATTACHMENT_POSITION));
 		isFirst = args.getBoolean(IS_FIRST);
 		conversationItemId =
@@ -94,7 +93,7 @@ public class ImageFragment extends Fragment
 		View v = inflater.inflate(R.layout.fragment_image, container,
 				false);
 
-		viewModel = ViewModelProviders.of(requireActivity(),
+		viewModel = ViewModelProviders.of(requireNonNull(getActivity()),
 				viewModelFactory).get(ImageViewModel.class);
 
 		photoView = v.findViewById(R.id.photoView);
@@ -111,9 +110,8 @@ public class ImageFragment extends Fragment
 			photoView.setImageResource(R.drawable.ic_image_missing);
 			startPostponedTransition();
 			// state is not final, so observe state changes
-			LifecycleOwner owner = getViewLifecycleOwner();
 			viewModel.getOnAttachmentReceived(attachment.getMessageId())
-					.observeEvent(owner, this::onAttachmentReceived);
+					.observeEvent(this, this::onAttachmentReceived);
 		}
 
 		return v;

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListFragment.java

@@ -47,6 +47,7 @@ import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
 import static com.google.android.material.snackbar.Snackbar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -94,7 +95,7 @@ public class ForumListFragment extends BaseEventFragment implements
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		requireActivity().setTitle(R.string.forums_button);
+		requireNonNull(getActivity()).setTitle(R.string.forums_button);
 
 		View contentView =
 				inflater.inflate(R.layout.fragment_forum_list, container,

briar-android/src/main/java/org/briarproject/briar/android/introduction/ContactChooserFragment.java

@@ -32,6 +32,7 @@ import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
@@ -83,7 +84,7 @@ public class ContactChooserFragment extends BaseFragment {
 					Contact c2 = item.getContact();
 					showMessageScreen(c1, c2);
 				};
-		adapter = new ContactListAdapter(requireActivity(),
+		adapter = new ContactListAdapter(requireNonNull(getActivity()),
 				onContactClickListener);
 
 		list = contentView.findViewById(R.id.list);
@@ -91,7 +92,8 @@ public class ContactChooserFragment extends BaseFragment {
 		list.setAdapter(adapter);
 		list.setEmptyText(R.string.no_contacts);
 
-		contactId = new ContactId(requireArguments().getInt(CONTACT_ID));
+		contactId = new ContactId(
+				requireNonNull(getArguments()).getInt(CONTACT_ID));
 
 		return contentView;
 	}

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java

@@ -39,6 +39,7 @@ import static android.app.Activity.RESULT_OK;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static android.widget.Toast.LENGTH_SHORT;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.util.UiUtils.getContactDisplayName;
@@ -101,7 +102,7 @@ public class IntroductionMessageFragment extends BaseFragment
 		}
 
 		// get contact IDs from fragment arguments
-		Bundle args = requireArguments();
+		Bundle args = requireNonNull(getArguments());
 		int contactId1 = args.getInt(CONTACT_ID_1, -1);
 		int contactId2 = args.getInt(CONTACT_ID_2, -1);
 		if (contactId1 == -1 || contactId2 == -1) {
@@ -211,7 +212,8 @@ public class IntroductionMessageFragment extends BaseFragment
 		introductionActivity.runOnDbThread(() -> {
 			// actually make the introduction
 			try {
-				introductionManager.makeIntroduction(c1, c2, text);
+				long timestamp = System.currentTimeMillis();
+				introductionManager.makeIntroduction(c1, c2, text, timestamp);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				introductionError();

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementFragment.java

@@ -54,6 +54,7 @@ import static android.view.View.VISIBLE;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.widget.LinearLayout.HORIZONTAL;
 import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -66,7 +67,6 @@ public class KeyAgreementFragment extends BaseEventFragment
 	static final String TAG = KeyAgreementFragment.class.getName();
 
 	private static final Logger LOG = Logger.getLogger(TAG);
-	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
 	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
 	@Inject
@@ -138,7 +138,8 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
+		requireNonNull(getActivity())
+				.setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
 		cameraView.setPreviewConsumer(new QrCodeDecoder(this));
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/login/OpenDatabaseFragment.java

@@ -16,7 +16,6 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -52,8 +51,7 @@ public class OpenDatabaseFragment extends BaseFragment {
 
 		StartupViewModel viewModel = ViewModelProviders.of(requireActivity(),
 				viewModelFactory).get(StartupViewModel.class);
-		LifecycleOwner owner = getViewLifecycleOwner();
-		viewModel.getState().observe(owner, this::onStateChanged);
+		viewModel.getState().observe(this, this::onStateChanged);
 
 		return v;
 	}

briar-android/src/main/java/org/briarproject/briar/android/login/PasswordFragment.java

@@ -23,7 +23,6 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
-import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -68,8 +67,7 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
 				.get(StartupViewModel.class);
 
-		LifecycleOwner owner = getViewLifecycleOwner();
-		viewModel.getPasswordValidated().observeEvent(owner, result -> {
+		viewModel.getPasswordValidated().observeEvent(this, result -> {
 			if (result != SUCCESS) onPasswordInvalid(result);
 		});
 

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupControllerImpl.java

@@ -7,8 +7,6 @@ import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
@@ -17,8 +15,6 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.briar.android.contactselection.ContactSelectorControllerImpl;
 import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.autodelete.AutoDeleteManager;
-import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.privategroup.GroupMessage;
 import org.briarproject.briar.api.privategroup.GroupMessageFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
@@ -39,8 +35,6 @@ import javax.inject.Inject;
 import androidx.annotation.Nullable;
 
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @Immutable
@@ -49,12 +43,9 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 		implements CreateGroupController {
 
 	private static final Logger LOG =
-			getLogger(CreateGroupControllerImpl.class.getName());
+			Logger.getLogger(CreateGroupControllerImpl.class.getName());
 
 	private final Executor cryptoExecutor;
-	private final TransactionManager db;
-	private final AutoDeleteManager autoDeleteManager;
-	private final ConversationManager conversationManager;
 	private final ContactManager contactManager;
 	private final IdentityManager identityManager;
 	private final PrivateGroupFactory groupFactory;
@@ -65,26 +56,16 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 	private final Clock clock;
 
 	@Inject
-	CreateGroupControllerImpl(
-			@DatabaseExecutor Executor dbExecutor,
+	CreateGroupControllerImpl(@DatabaseExecutor Executor dbExecutor,
 			@CryptoExecutor Executor cryptoExecutor,
-			TransactionManager db,
-			AutoDeleteManager autoDeleteManager,
-			ConversationManager conversationManager,
-			LifecycleManager lifecycleManager,
-			ContactManager contactManager,
-			IdentityManager identityManager,
-			PrivateGroupFactory groupFactory,
+			LifecycleManager lifecycleManager, ContactManager contactManager,
+			IdentityManager identityManager, PrivateGroupFactory groupFactory,
 			GroupMessageFactory groupMessageFactory,
 			PrivateGroupManager groupManager,
 			GroupInvitationFactory groupInvitationFactory,
-			GroupInvitationManager groupInvitationManager,
-			Clock clock) {
+			GroupInvitationManager groupInvitationManager, Clock clock) {
 		super(dbExecutor, lifecycleManager, contactManager);
 		this.cryptoExecutor = cryptoExecutor;
-		this.db = db;
-		this.autoDeleteManager = autoDeleteManager;
-		this.conversationManager = conversationManager;
 		this.contactManager = contactManager;
 		this.identityManager = identityManager;
 		this.groupFactory = groupFactory;
@@ -148,14 +129,16 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 			ResultExceptionHandler<Void, DbException> handler) {
 		runOnDbThread(() -> {
 			try {
-				db.transaction(true, txn -> {
-					LocalAuthor localAuthor =
-							identityManager.getLocalAuthor(txn);
-					List<InvitationContext> contexts =
-							createInvitationContexts(txn, contactIds);
-					txn.attach(() -> signInvitations(g, localAuthor, contexts,
-							text, handler));
-				});
+				LocalAuthor localAuthor = identityManager.getLocalAuthor();
+				List<Contact> contacts = new ArrayList<>();
+				for (ContactId c : contactIds) {
+					try {
+						contacts.add(contactManager.getContact(c));
+					} catch (NoSuchContactException e) {
+						// Continue
+					}
+				}
+				signInvitations(g, localAuthor, contacts, text, handler);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				handler.onException(e);
@@ -163,32 +146,17 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 		});
 	}
 
-	private List<InvitationContext> createInvitationContexts(Transaction txn,
-			Collection<ContactId> contactIds) throws DbException {
-		List<InvitationContext> contexts = new ArrayList<>();
-		for (ContactId c : contactIds) {
-			try {
-				Contact contact = contactManager.getContact(txn, c);
-				long timestamp = conversationManager
-						.getTimestampForOutgoingMessage(txn, c);
-				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
-						timestamp);
-				contexts.add(new InvitationContext(contact, timestamp, timer));
-			} catch (NoSuchContactException e) {
-				// Continue
-			}
-		}
-		return contexts;
-	}
-
 	private void signInvitations(GroupId g, LocalAuthor localAuthor,
-			List<InvitationContext> contexts, @Nullable String text,
+			Collection<Contact> contacts, @Nullable String text,
 			ResultExceptionHandler<Void, DbException> handler) {
 		cryptoExecutor.execute(() -> {
-			for (InvitationContext ctx : contexts) {
-				ctx.signature = groupInvitationFactory.signInvitation(
-						ctx.contact, g, ctx.timestamp,
-						localAuthor.getPrivateKey());
+			long timestamp = clock.currentTimeMillis();
+			List<InvitationContext> contexts = new ArrayList<>();
+			for (Contact c : contacts) {
+				byte[] signature = groupInvitationFactory.signInvitation(c, g,
+						timestamp, localAuthor.getPrivateKey());
+				contexts.add(new InvitationContext(c.getId(), timestamp,
+						signature));
 			}
 			sendInvitations(g, contexts, text, handler);
 		});
@@ -199,16 +167,16 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 			ResultExceptionHandler<Void, DbException> handler) {
 		runOnDbThread(() -> {
 			try {
-				for (InvitationContext ctx : contexts) {
+				for (InvitationContext context : contexts) {
 					try {
 						groupInvitationManager.sendInvitation(g,
-								ctx.contact.getId(), text, ctx.timestamp,
-								requireNonNull(ctx.signature),
-								ctx.autoDeleteTimer);
+								context.contactId, text, context.timestamp,
+								context.signature);
 					} catch (NoSuchContactException e) {
 						// Continue
 					}
 				}
+				//noinspection ConstantConditions
 				handler.onResult(null);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
@@ -219,16 +187,15 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 
 	private static class InvitationContext {
 
-		private final Contact contact;
-		private final long timestamp, autoDeleteTimer;
-		@Nullable
-		private byte[] signature = null;
+		private final ContactId contactId;
+		private final long timestamp;
+		private final byte[] signature;
 
-		private InvitationContext(Contact contact, long timestamp,
-				long autoDeleteTimer) {
-			this.contact = contact;
+		private InvitationContext(ContactId contactId, long timestamp,
+				byte[] signature) {
+			this.contactId = contactId;
 			this.timestamp = timestamp;
-			this.autoDeleteTimer = autoDeleteTimer;
+			this.signature = signature;
 		}
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/GroupInviteFragment.java

@@ -15,6 +15,7 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @MethodsNotNullByDefault
@@ -42,7 +43,7 @@ public class GroupInviteFragment extends ContactSelectorFragment {
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
-		requireActivity().setTitle(R.string.groups_invite_members);
+		requireNonNull(getActivity()).setTitle(R.string.groups_invite_members);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -39,6 +39,7 @@ import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
 import static com.google.android.material.snackbar.Snackbar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -71,7 +72,7 @@ public class GroupListFragment extends BaseFragment implements
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		requireActivity().setTitle(R.string.groups_button);
+		requireNonNull(getActivity()).setTitle(R.string.groups_button);
 
 		View v = inflater.inflate(R.layout.list, container, false);
 

briar-android/src/main/java/org/briarproject/briar/android/reporting/CrashFragment.java

@@ -12,6 +12,8 @@ import org.briarproject.briar.R;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 
+import static java.util.Objects.requireNonNull;
+
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class CrashFragment extends Fragment {
@@ -33,7 +35,7 @@ public class CrashFragment extends Fragment {
 	}
 
 	private DevReportActivity getDevReportActivity() {
-		return (DevReportActivity) requireActivity();
+		return (DevReportActivity) requireNonNull(getActivity());
 	}
 
 }