TheArchive/session-android
1
0
Fork 0
mirror of https://github.com/oxen-io/session-android.git synced 2024-11-27 12:05:22 +00:00
Code Issues Packages Projects Releases Wiki Activity

Add padding for push messages.

Browse Source 
1) Use 'bit padding.'

1) By default, pad at 160 byte increments.
This commit is contained in:
Moxie Marlinspike 2014-07-09 14:36:01 -07:00
parent fcaa3f0d73
commit 07fd17ccda
5 changed files with 77 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
libaxolotl/src/main/java/org/whispersystems/libaxolotl/SessionCipher.java
View File

@ -168,6 +168,13 @@ public class SessionCipher {
}
WhisperMessage ciphertextMessage = new WhisperMessage(decodedMessage);
if (ciphertextMessage.getMessageVersion() != sessionState.getSessionVersion()) {
throw new InvalidMessageException(String.format("Message version %d, but session version %d",
ciphertextMessage.getMessageVersion(),
sessionState.getSessionVersion()));
}
ECPublicKey theirEphemeral = ciphertextMessage.getSenderEphemeral();
int counter = ciphertextMessage.getCounter();
ChainKey chainKey = getOrCreateChainKey(sessionState, theirEphemeral);

48
library/src/org/whispersystems/textsecure/push/PushTransportDetails.java
View File

@ -16,20 +16,53 @@
*/
package org.whispersystems.textsecure.push;
import android.util.Log;
import org.whispersystems.textsecure.crypto.TransportDetails;
import org.whispersystems.textsecure.util.Base64;
import java.io.IOException;
public class PushTransportDetails implements TransportDetails {
private final int messageVersion;
public PushTransportDetails(int messageVersion) {
this.messageVersion = messageVersion;
}
@Override
public byte[] getStrippedPaddingMessageBody(byte[] messageWithPadding) {
if (messageVersion < 2) throw new AssertionError("Unknown version: " + messageVersion);
else if (messageVersion == 2) return messageWithPadding;
int paddingStart = 0;
for (int i=messageWithPadding.length-1;i>=0;i--) {
if (messageWithPadding[i] == (byte)0x80) {
paddingStart = i;
break;
} else if (messageWithPadding[i] != (byte)0x00) {
Log.w("PushTransportDetails", "Padding byte is malformed, returning unstripped padding.");
return messageWithPadding;
}
}
byte[] strippedMessage = new byte[messageWithPadding.length - paddingStart];
System.arraycopy(messageWithPadding, 0, strippedMessage, 0, strippedMessage.length);
return strippedMessage;
}
@Override
public byte[] getPaddedMessageBody(byte[] messageBody) {
return messageBody;
if (messageVersion < 2) throw new AssertionError("Unknown version: " + messageVersion);
else if (messageVersion == 2) return messageBody;
byte[] paddedMessage = new byte[getPaddedMessageLength(messageBody.length)];
System.arraycopy(messageBody, 0, paddedMessage, 0, messageBody.length);
paddedMessage[messageBody.length] = (byte)0x80;
return paddedMessage;
}
@Override
@ -41,4 +74,15 @@ public class PushTransportDetails implements TransportDetails {
public byte[] getDecodedMessage(byte[] encodedMessageBytes) throws IOException {
return encodedMessageBytes;
}
private int getPaddedMessageLength(int messageLength) {
int messageLengthWithTerminator = messageLength + 1;
int messagePartCount = messageLengthWithTerminator / 160;
if (messageLengthWithTerminator % 160 != 0) {
messagePartCount++;
}
return messagePartCount * 160;
}
}

11
library/src/org/whispersystems/textsecure/storage/SessionUtil.java
View File

@ -7,6 +7,17 @@ import org.whispersystems.textsecure.crypto.MasterSecret;
public class SessionUtil {
public static int getSessionVersion(Context context,
MasterSecret masterSecret,
RecipientDevice recipient)
{
return
new TextSecureSessionStore(context, masterSecret)
.loadSession(recipient.getRecipientId(), recipient.getDeviceId())
.getSessionState()
.getSessionVersion();
}
public static boolean hasEncryptCapableSession(Context context,
MasterSecret masterSecret,
CanonicalRecipient recipient)

7
src/org/thoughtcrime/securesms/crypto/DecryptingQueue.java
View File

@ -52,8 +52,11 @@ import org.whispersystems.libaxolotl.protocol.WhisperMessage;
import org.whispersystems.libaxolotl.state.SessionStore;
import org.whispersystems.textsecure.crypto.MasterSecret;
import org.whispersystems.textsecure.crypto.SessionCipherFactory;
import org.whispersystems.textsecure.crypto.TransportDetails;
import org.whispersystems.textsecure.push.IncomingPushMessage;
import org.whispersystems.textsecure.push.PushTransportDetails;
import org.whispersystems.textsecure.storage.RecipientDevice;
import org.whispersystems.textsecure.storage.SessionUtil;
import org.whispersystems.textsecure.storage.TextSecureSessionStore;
import org.whispersystems.textsecure.util.Base64;
import org.whispersystems.textsecure.util.Hex;
@ -210,10 +213,12 @@ public class DecryptingQueue {
return;
}
int sessionVersion = SessionUtil.getSessionVersion(context, masterSecret, recipientDevice);
SessionCipher sessionCipher = SessionCipherFactory.getInstance(context, masterSecret, recipientDevice);
byte[] plaintextBody = sessionCipher.decrypt(message.getBody());
TransportDetails transport = new PushTransportDetails(sessionVersion);
message = message.withBody(plaintextBody);
message = message.withBody(transport.getStrippedPaddingMessageBody(plaintextBody));
sendResult(PushReceiver.RESULT_OK);
} catch (InvalidMessageException | LegacyMessageException | RecipientFormattingException e) {
Log.w("DecryptionQueue", e);

5
src/org/thoughtcrime/securesms/transport/PushTransport.java
View File

@ -52,6 +52,7 @@ import org.whispersystems.textsecure.push.PushAttachmentPointer;
import org.whispersystems.textsecure.push.PushBody;
import org.whispersystems.textsecure.push.PushMessageProtos.PushMessageContent;
import org.whispersystems.textsecure.push.PushServiceSocket;
import org.whispersystems.textsecure.push.PushTransportDetails;
import org.whispersystems.textsecure.push.StaleDevices;
import org.whispersystems.textsecure.push.StaleDevicesException;
import org.whispersystems.textsecure.push.UnregisteredUserException;
@ -344,8 +345,10 @@ public class PushTransport extends BaseTransport {
}
}
int sessionVersion = SessionUtil.getSessionVersion(context, masterSecret, pushAddress);
SessionCipher cipher = SessionCipherFactory.getInstance(context, masterSecret, pushAddress);
CiphertextMessage message = cipher.encrypt(plaintext);
byte[] paddedPlaintext = new PushTransportDetails(sessionVersion).getPaddedMessageBody(plaintext);
CiphertextMessage message = cipher.encrypt(paddedPlaintext);
int remoteRegistrationId = cipher.getRemoteRegistrationId();
if (message.getType() == CiphertextMessage.PREKEY_TYPE) {