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Code Issues Projects Releases Wiki Activity

Derive separate keys for each direction.

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This commit is contained in:
akwizgran
2011-08-14 12:18:16 +02:00
parent 254da2da27
commit 4497774311
10 changed files with 115 additions and 23 deletions
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12
api/net/sf/briar/api/crypto/CryptoComponent.java
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@@ -10,11 +10,17 @@ import javax.crypto.SecretKey;
public interface CryptoComponent {
SecretKey deriveMacKey(byte[] secret);
SecretKey deriveIncomingMacKey(byte[] secret);
SecretKey derivePacketKey(byte[] secret);
SecretKey deriveIncomingPacketKey(byte[] secret);
SecretKey deriveTagKey(byte[] secret);
SecretKey deriveIncomingTagKey(byte[] secret);
SecretKey deriveOutgoingMacKey(byte[] secret);
SecretKey deriveOutgoingPacketKey(byte[] secret);
SecretKey deriveOutgoingTagKey(byte[] secret);
KeyPair generateKeyPair();

39
components/net/sf/briar/crypto/CryptoComponentImpl.java
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@@ -68,9 +68,13 @@ class CryptoComponentImpl implements CryptoComponent {
}
}
public SecretKey deriveMacKey(byte[] secret) {
public SecretKey deriveIncomingMacKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
if(s.getAlice()) return deriveKey("MACA", s.getIv(), s.getCiphertext());
return deriveMacKey(s, !s.getAlice());
}
private SecretKey deriveMacKey(SharedSecret s, boolean alice) {
if(alice) return deriveKey("MACA", s.getIv(), s.getCiphertext());
else return deriveKey("MACB", s.getIv(), s.getCiphertext());
}
@@ -110,18 +114,41 @@ class CryptoComponentImpl implements CryptoComponent {
}
}
public SecretKey derivePacketKey(byte[] secret) {
public SecretKey deriveIncomingPacketKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
if(s.getAlice()) return deriveKey("PKTA", s.getIv(), s.getCiphertext());
return derivePacketKey(s, !s.getAlice());
}
private SecretKey derivePacketKey(SharedSecret s, boolean alice) {
if(alice) return deriveKey("PKTA", s.getIv(), s.getCiphertext());
else return deriveKey("PKTB", s.getIv(), s.getCiphertext());
}
public SecretKey deriveTagKey(byte[] secret) {
public SecretKey deriveIncomingTagKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
if(s.getAlice()) return deriveKey("TAGA", s.getIv(), s.getCiphertext());
return deriveTagKey(s, !s.getAlice());
}
private SecretKey deriveTagKey(SharedSecret s, boolean alice) {
if(alice) return deriveKey("TAGA", s.getIv(), s.getCiphertext());
else return deriveKey("TAGB", s.getIv(), s.getCiphertext());
}
public SecretKey deriveOutgoingMacKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
return deriveMacKey(s, s.getAlice());
}
public SecretKey deriveOutgoingPacketKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
return derivePacketKey(s, s.getAlice());
}
public SecretKey deriveOutgoingTagKey(byte[] secret) {
SharedSecret s = new SharedSecret(secret);
return deriveTagKey(s, s.getAlice());
}
public KeyPair generateKeyPair() {
return keyPairGenerator.generateKeyPair();
}

3
components/net/sf/briar/transport/ConnectionRecogniserImpl.java
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@@ -50,7 +50,8 @@ DatabaseListener {
for(ContactId c : db.getContacts()) {
try {
// Initialise and store the contact's tag cipher
SecretKey tagKey = crypto.deriveTagKey(db.getSharedSecret(c));
byte[] secret = db.getSharedSecret(c);
SecretKey tagKey = crypto.deriveIncomingTagKey(secret);
Cipher cipher = crypto.getTagCipher();
try {
cipher.init(Cipher.ENCRYPT_MODE, tagKey);

6
components/net/sf/briar/transport/PacketReaderFactoryImpl.java
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@@ -24,9 +24,9 @@ class PacketReaderFactoryImpl implements PacketReaderFactory {
public PacketReader createPacketReader(byte[] firstTag, InputStream in,
int transportId, long connection, byte[] secret) {
SecretKey macKey = crypto.deriveMacKey(secret);
SecretKey tagKey = crypto.deriveTagKey(secret);
SecretKey packetKey = crypto.derivePacketKey(secret);
SecretKey macKey = crypto.deriveIncomingMacKey(secret);
SecretKey tagKey = crypto.deriveIncomingTagKey(secret);
SecretKey packetKey = crypto.deriveIncomingPacketKey(secret);
Cipher tagCipher = crypto.getTagCipher();
Cipher packetCipher = crypto.getPacketCipher();
Mac mac = crypto.getMac();

6
components/net/sf/briar/transport/PacketWriterFactoryImpl.java
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@@ -24,9 +24,9 @@ class PacketWriterFactoryImpl implements PacketWriterFactory {
public PacketWriter createPacketWriter(OutputStream out, int transportId,
long connection, byte[] secret) {
SecretKey macKey = crypto.deriveMacKey(secret);
SecretKey tagKey = crypto.deriveTagKey(secret);
SecretKey packetKey = crypto.derivePacketKey(secret);
SecretKey macKey = crypto.deriveOutgoingMacKey(secret);
SecretKey tagKey = crypto.deriveOutgoingTagKey(secret);
SecretKey packetKey = crypto.deriveOutgoingPacketKey(secret);
Cipher tagCipher = crypto.getTagCipher();
Cipher packetCipher = crypto.getPacketCipher();
Mac mac = crypto.getMac();

2
test/build.xml
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@@ -16,6 +16,8 @@
<test name='net.sf.briar.FileReadWriteTest'/>
<test name='net.sf.briar.LockFairnessTest'/>
<test name='net.sf.briar.crypto.CounterModeTest'/>
<test name='net.sf.briar.crypto.CryptoComponentTest'/>
<test name='net.sf.briar.crypto.SharedSecretTest'/>
<test name='net.sf.briar.db.BasicH2Test'/>
<test name='net.sf.briar.db.DatabaseCleanerImplTest'/>
<test name='net.sf.briar.db.H2DatabaseTest'/>

12
test/net/sf/briar/FileReadWriteTest.java
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@@ -71,7 +71,7 @@ public class FileReadWriteTest extends TestCase {
private final ProtocolReaderFactory protocolReaderFactory;
private final ProtocolWriterFactory protocolWriterFactory;
private final CryptoComponent crypto;
private final byte[] secret = new byte[45];
private final byte[] aliceSecret, bobSecret;
private final int transportId = 123;
private final long connection = 234L;
private final Author author;
@@ -94,6 +94,10 @@ public class FileReadWriteTest extends TestCase {
crypto = i.getInstance(CryptoComponent.class);
assertEquals(crypto.getMessageDigest().getDigestLength(),
UniqueId.LENGTH);
// Create matching secrets: one for Alice, one for Bob
aliceSecret = new byte[45];
aliceSecret[16] = (byte) 1;
bobSecret = new byte[45];
// Create two groups: one restricted, one unrestricted
GroupFactory groupFactory = i.getInstance(GroupFactory.class);
group = groupFactory.createGroup("Unrestricted group", null);
@@ -129,8 +133,9 @@ public class FileReadWriteTest extends TestCase {
@Test
public void testWriteFile() throws Exception {
OutputStream out = new FileOutputStream(file);
// Use Alice's secret for writing
PacketWriter packetWriter = packetWriterFactory.createPacketWriter(out,
transportId, connection, secret);
transportId, connection, aliceSecret);
out = packetWriter.getOutputStream();
AckWriter a = protocolWriterFactory.createAckWriter(out);
@@ -194,8 +199,9 @@ public class FileReadWriteTest extends TestCase {
offset += read;
}
assertEquals(16, offset);
// Use Bob's secret for reading
PacketReader packetReader = packetReaderFactory.createPacketReader(
firstTag, in, transportId, connection, secret);
firstTag, in, transportId, connection, bobSecret);
in = packetReader.getInputStream();
ProtocolReader protocolReader =
protocolReaderFactory.createProtocolReader(in);

49
test/net/sf/briar/crypto/CryptoComponentTest.java Normal file
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@@ -0,0 +1,49 @@
package net.sf.briar.crypto;
import junit.framework.TestCase;
import net.sf.briar.api.crypto.CryptoComponent;
import org.junit.Test;
import com.google.inject.Guice;
import com.google.inject.Injector;
public class CryptoComponentTest extends TestCase {
private final CryptoComponent crypto;
public CryptoComponentTest() {
super();
Injector i = Guice.createInjector(new CryptoModule());
crypto = i.getInstance(CryptoComponent.class);
}
@Test
public void testKeyDerivation() {
// Create matching secrets: one for Alice, one for Bob
byte[] aliceSecret = new byte[123];
aliceSecret[SharedSecret.IV_BYTES] = (byte) 1;
byte[] bobSecret = new byte[123];
// Check that Alice's incoming keys match Bob's outgoing keys
assertEquals(crypto.deriveIncomingMacKey(aliceSecret),
crypto.deriveOutgoingMacKey(bobSecret));
assertEquals(crypto.deriveIncomingPacketKey(aliceSecret),
crypto.deriveOutgoingPacketKey(bobSecret));
assertEquals(crypto.deriveIncomingTagKey(aliceSecret),
crypto.deriveOutgoingTagKey(bobSecret));
// Check that Alice's outgoing keys match Bob's incoming keys
assertEquals(crypto.deriveOutgoingMacKey(aliceSecret),
crypto.deriveIncomingMacKey(bobSecret));
assertEquals(crypto.deriveOutgoingPacketKey(aliceSecret),
crypto.deriveIncomingPacketKey(bobSecret));
assertEquals(crypto.deriveOutgoingTagKey(aliceSecret),
crypto.deriveIncomingTagKey(bobSecret));
// Check that Alice's incoming and outgoing keys are different
assertFalse(crypto.deriveIncomingMacKey(aliceSecret).equals(
crypto.deriveOutgoingMacKey(aliceSecret)));
assertFalse(crypto.deriveIncomingPacketKey(aliceSecret).equals(
crypto.deriveOutgoingPacketKey(aliceSecret)));
assertFalse(crypto.deriveIncomingTagKey(aliceSecret).equals(
crypto.deriveOutgoingTagKey(aliceSecret)));
}
}

2
test/net/sf/briar/transport/ConnectionRecogniserImplTest.java
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@@ -60,7 +60,7 @@ public class ConnectionRecogniserImplTest extends TestCase {
@Test
public void testExpectedTag() throws Exception {
// Calculate the expected tag for connection number 3
SecretKey tagKey = crypto.deriveTagKey(secret);
SecretKey tagKey = crypto.deriveIncomingTagKey(secret);
Cipher tagCipher = crypto.getTagCipher();
tagCipher.init(Cipher.ENCRYPT_MODE, tagKey);
byte[] tag = TagEncoder.encodeTag(transportId, 3L, 0);

7
test/net/sf/briar/transport/PacketReadWriteTest.java
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@@ -39,9 +39,10 @@ public class PacketReadWriteTest extends TestCase {
crypto = i.getInstance(CryptoComponent.class);
tagCipher = crypto.getTagCipher();
packetCipher = crypto.getPacketCipher();
macKey = crypto.deriveMacKey(secret);
tagKey = crypto.deriveTagKey(secret);
packetKey = crypto.derivePacketKey(secret);
// Since we're sending packets to ourselves, we only need outgoing keys
macKey = crypto.deriveOutgoingMacKey(secret);
tagKey = crypto.deriveOutgoingTagKey(secret);
packetKey = crypto.deriveOutgoingPacketKey(secret);
mac = crypto.getMac();
random = new Random();
}