Fixes #530

Signal.xcodeproj/project.pbxproj

@@ -305,6 +305,7 @@
 		B60FB9A71A46F099006A5A66 /* TSAllocAttachmentRequest.m in Sources */ = {isa = PBXBuildFile; fileRef = B60FB9A61A46F099006A5A66 /* TSAllocAttachmentRequest.m */; };
 		B60FB9AD1A46F831006A5A66 /* UIImage+contentTypes.m in Sources */ = {isa = PBXBuildFile; fileRef = B60FB9AC1A46F831006A5A66 /* UIImage+contentTypes.m */; };
 		B60FB9B01A4711D4006A5A66 /* TSAttachmentEncryptionResult.m in Sources */ = {isa = PBXBuildFile; fileRef = B60FB9AF1A4711D4006A5A66 /* TSAttachmentEncryptionResult.m */; };
+		B617E9241A9F962600753F00 /* MessagePaddingTests.m in Sources */ = {isa = PBXBuildFile; fileRef = B617E9231A9F962600753F00 /* MessagePaddingTests.m */; };
 		B62D53F71A23CCAD009AAF82 /* TSMessageAdapter.m in Sources */ = {isa = PBXBuildFile; fileRef = B62D53F61A23CCAD009AAF82 /* TSMessageAdapter.m */; };
 		B62EFBEC1A91352F0072ADD3 /* TSInvalidIdentityKeyErrorMessage.m in Sources */ = {isa = PBXBuildFile; fileRef = B62EFBE71A91352F0072ADD3 /* TSInvalidIdentityKeyErrorMessage.m */; };
 		B62EFBED1A91352F0072ADD3 /* TSInvalidIdentityKeyReceivingErrorMessage.m in Sources */ = {isa = PBXBuildFile; fileRef = B62EFBE91A91352F0072ADD3 /* TSInvalidIdentityKeyReceivingErrorMessage.m */; };
@@ -872,6 +873,7 @@
 		B60FB9AC1A46F831006A5A66 /* UIImage+contentTypes.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UIImage+contentTypes.m"; sourceTree = "<group>"; };
 		B60FB9AE1A4711D4006A5A66 /* TSAttachmentEncryptionResult.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TSAttachmentEncryptionResult.h; sourceTree = "<group>"; };
 		B60FB9AF1A4711D4006A5A66 /* TSAttachmentEncryptionResult.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = TSAttachmentEncryptionResult.m; sourceTree = "<group>"; };
+		B617E9231A9F962600753F00 /* MessagePaddingTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MessagePaddingTests.m; sourceTree = "<group>"; };
 		B62D53F51A23CCAD009AAF82 /* TSMessageAdapter.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TSMessageAdapter.h; sourceTree = "<group>"; };
 		B62D53F61A23CCAD009AAF82 /* TSMessageAdapter.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = TSMessageAdapter.m; sourceTree = "<group>"; };
 		B62EFBE61A91352F0072ADD3 /* TSInvalidIdentityKeyErrorMessage.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TSInvalidIdentityKeyErrorMessage.h; sourceTree = "<group>"; };
@@ -2232,6 +2234,7 @@
 				B6B095E21A1D25C5008BFAA6 /* TSStoragePreKeyStoreTests.m */,
 				B6B095E31A1D25C5008BFAA6 /* TSStorageSignedPreKeyStore.m */,
 				B640C4761A477B0F005C7C8A /* TSAttachementsTest.m */,
+				B617E9231A9F962600753F00 /* MessagePaddingTests.m */,
 			);
 			path = textsecure;
 			sourceTree = "<group>";
@@ -3817,6 +3820,7 @@
 				76EB062918170B33006006FC /* BadArgument.m in Sources */,
 				A157076A17F0CD6D007C2BD6 /* ZrtpTest.m in Sources */,
 				A157076B17F0CD6D007C2BD6 /* LowLatencyConnectorTest.m in Sources */,
+				B617E9241A9F962600753F00 /* MessagePaddingTests.m in Sources */,
 				B65031CF1A7862AA002EBBBD /* SignedPreKeyDeletionTests.m in Sources */,
 				76EB061718170B33006006FC /* AnonymousOccurrenceLogger.m in Sources */,
 				76EB05F118170B33006006FC /* PhoneManager.m in Sources */,

Signal/src/textsecure/Messages/TSMessagesManager+sendMessages.m

@@ -16,6 +16,7 @@
 #import "Environment.h"
 #import "PreferencesUtil.h"
 #import "IncomingPushMessageSignal.pb.h"
+#import "NSData+messagePadding.h"
 #import "TSStorageManager.h"
 #import "TSStorageManager+SessionStore.h"
 #import "TSStorageManager+IdentityKeyStore.h"
@@ -237,7 +238,7 @@ dispatch_queue_t sendingQueue() {
                                                             recipientId:identifier
                                                                deviceId:[deviceNumber intValue]];
     
-    id<CipherMessage> encryptedMessage = [cipher encryptMessage:plainText];
+    id<CipherMessage> encryptedMessage = [cipher encryptMessage:[plainText paddedMessageBody]];
     NSData *serializedMessage = encryptedMessage.serialized;
     TSWhisperMessageType messageType = [self messageTypeForCipherMessage:encryptedMessage];
     

Signal/src/textsecure/Util/NSData+messagePadding.h

@@ -12,4 +12,6 @@
 
 - (NSData*)removePadding;
 
+- (NSData*)paddedMessageBody;
+
 @end

Signal/src/textsecure/Util/NSData+messagePadding.m

@@ -16,12 +16,12 @@
     Byte data[self.length];
     [self getBytes:data length:self.length];
     
-    
     for (long i = (long)self.length-1; i >= 0; i--) {
         if (data[i] == (Byte)0x80) {
             paddingStart = (unsigned long) i;
             break;
         } else if (data[i] != (Byte)0x00) {
+            DDLogWarn(@"Failed to remove padding, returning unstripped padding");
             return self;
         }
     }
@@ -29,4 +29,33 @@
     return [self subdataWithRange:NSMakeRange(0, paddingStart)];
 }
 
+
+- (NSData*)paddedMessageBody {
+    // From https://github.com/WhisperSystems/TextSecure/blob/master/libtextsecure/src/main/java/org/whispersystems/textsecure/internal/push/PushTransportDetails.java#L55
+    // NOTE: This is dumb.  We have our own padding scheme, but so does the cipher.
+    // The +1 -1 here is to make sure the Cipher has room to add one padding byte,
+    // otherwise it'll add a full 16 extra bytes.
+    
+    NSUInteger    paddedMessageLength = [self paddedMessageLength:(self.length + 1)]-1;
+    NSMutableData *paddedMessage      = [NSMutableData dataWithLength:paddedMessageLength];
+    
+    Byte paddingByte = 0x80;
+    
+    [paddedMessage replaceBytesInRange:NSMakeRange(0, self.length) withBytes:[self bytes]];
+    [paddedMessage replaceBytesInRange:NSMakeRange(self.length, 1) withBytes:&paddingByte];
+    
+    return paddedMessage;
+}
+
+- (NSUInteger)paddedMessageLength:(NSUInteger)messageLength {
+    NSUInteger messageLengthWithTerminator = messageLength + 1;
+    NSUInteger messagePartCount            = messageLengthWithTerminator / 160;
+    
+    if (messageLengthWithTerminator % 160 != 0) {
+        messagePartCount++;
+    }
+    
+    return messagePartCount * 160;
+}
+
 @end

Signal/test/textsecure/MessagePaddingTests.m

@@ -0,0 +1,44 @@
+//
+//  MessagePaddingTests.m
+//  Signal
+//
+//  Created by Frederic Jacobs on 26/02/15.
+//  Copyright (c) 2015 Open Whisper Systems. All rights reserved.
+//
+
+#import "Cryptography.h"
+#import "NSData+messagePadding.h"
+#import <XCTest/XCTest.h>
+
+@interface MessagePaddingTests : XCTestCase
+
+@end
+
+@implementation MessagePaddingTests
+
+- (void)testV3Padding {
+    for (NSUInteger i=0;i<159;i++) {
+        NSData *data = [NSMutableData dataWithLength:i];
+        XCTAssert([data paddedMessageBody].length == 159);
+    }
+    
+    for (NSUInteger i=159;i<319;i++) {
+        NSData *data = [NSMutableData dataWithLength:i];
+        XCTAssert([data paddedMessageBody].length == 319);
+    }
+    
+    for (NSUInteger i=319;i<479;i++) {
+        NSData *data = [NSMutableData dataWithLength:i];
+        XCTAssert([data paddedMessageBody].length == 479);
+    }
+}
+
+- (void)testV3RandomPadding{
+    for (int i = 0; i < 1000; i++) {
+        NSData *randomMessage = [Cryptography generateRandomBytes:501];
+        NSData *paddedMessage = [randomMessage paddedMessageBody];
+        XCTAssert([[paddedMessage removePadding] isEqualToData:randomMessage]);
+    }
+}
+
+@end

Signal/translations/en.lproj/Localizable.strings

@@ -13,7 +13,7 @@
 "DATESTRING_TODAY" = "Today";
 "DISABLING_BACKUP_FAILED" = "We encountered an issue while disabling the backup of your call log. Call logs might leak in your iTunes/iCloud backups.";
 "ERROR_WAS_DETECTED_TITLE" = "Bummer!";
-"ERROR_WAS_DETECTED_SUBMIT" = "An bug was detected. Help us make Signal better by reporting this incident.";
+"ERROR_WAS_DETECTED_SUBMIT" = "A bug was detected. Help us make Signal better by reporting this incident.";
 "END_CALL_BAD_INTERACTION_WITH_SERVER" = "Server Failed!";
 "END_CALL_BUTTON_TITLE" = "End";
 "END_CALL_HANDSHAKE_FAILED" = "Handshake Failed!";