OSX/sec/Security/SecOTRSession.c

   1 /*
   2  * Copyright (c) 2011-2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 #include <stdint.h>
  26 #include <sys/types.h>
  27 #include <CoreFoundation/CFDate.h>
  28
  29 #include "SecOTRSession.h"
  30
  31 #include "SecOTRMath.h"
  32 #include "SecOTRDHKey.h"
  33 #include "SecOTRSessionPriv.h"
  34 #include "SecOTRPackets.h"
  35 #include "SecOTRPacketData.h"
  36 #include "SecOTRIdentityPriv.h"
  37
  38 #include <utilities/SecCFWrappers.h>
  39
  40 #include <CoreFoundation/CFRuntime.h>
  41 #include <CoreFoundation/CFString.h>
  42
  43 #include <Security/SecBasePriv.h>
  44 #include <Security/SecRandom.h>
  45 #include <Security/SecBase64.h>
  46 #include <Security/SecKeyPriv.h>
  47
  48 #include <Security/SecureObjectSync/SOSPeerInfo.h>
  49 #include <Security/SecureObjectSync/SOSCircle.h>
  50 #include <Security/SecureObjectSync/SOSCloudCircle.h>
  51 #include <Security/SecureObjectSync/SOSInternal.h>
  52 #include <Security/SecureObjectSync/SOSUserKeygen.h>
  53
  54 #include <AssertMacros.h>
  55
  56 #include <corecrypto/cchmac.h>
  57 #include <corecrypto/ccsha2.h>
  58 #include <corecrypto/ccsha1.h>
  59
  60 #include <string.h>
  61 #include <stdlib.h>
  62
  63 #include <syslog.h>
  64 #include <os/activity.h>
  65
  66 #include <utilities/array_size.h>
  67
  68 #include <ipc/securityd_client.h>
  69 #include <Security/SecuritydXPC.h>
  70
  71 CFGiblisFor(SecOTRSession);
  72
  73 static uint64_t setup_defaults_settings(){
  74
  75     Boolean keyExistsAndHasValue = false;
  76     uint64_t seconds;
  77     seconds = CFPreferencesGetAppIntegerValue(CFSTR("OTR"), CFSTR("com.apple.security"), &keyExistsAndHasValue);
  78     secdebug("OTR", "Retrieving OTR default settings was success? %d value retrieved: %llu", keyExistsAndHasValue, seconds);
  79     return keyExistsAndHasValue ? seconds : (kSecondsPerMinute * 15); //15 minutes by default
  80 }
  81
  82 static uint64_t SecOTRGetDefaultsWriteSeconds(void) {
  83     static dispatch_once_t sdOnceToken;
  84     static uint64_t seconds;
  85
  86     dispatch_once(&sdOnceToken, ^{
  87         seconds = setup_defaults_settings();
  88     });
  89
  90     return seconds;
  91 }
  92
  93 static void SecOTRSEnableTimeToRoll(SecOTRSessionRef session){
  94     CFAbsoluteTime now = CFAbsoluteTimeGetCurrent();
  95     CFAbsoluteTime nextTimeToRoll = now + session->_stallSeconds;
  96
  97     if(session->_timeToRoll == 0 || session->_timeToRoll > nextTimeToRoll){
  98         session->_timeToRoll = nextTimeToRoll;
  99     }
 100 }
 101
 102 static void SecOTRSExpireCachedKeysForFullKey(SecOTRSessionRef session, SecOTRFullDHKeyRef myKey)
 103 {
 104     for(int i = 0; i < kOTRKeyCacheSize; ++i)
 105     {
 106         if (0 == timingsafe_bcmp(session->_keyCache[i]._fullKeyHash, SecFDHKGetHash(myKey), CCSHA1_OUTPUT_SIZE)) {
 107             CFDataAppendBytes(session->_macKeysToExpose, session->_keyCache[i]._receiveMacKey, sizeof(session->_keyCache[i]._receiveMacKey));
 108             bzero(&session->_keyCache[i], sizeof(session->_keyCache[i]));
 109         }
 110     }
 111 }
 112
 113 static void SecOTRSExpireCachedKeysForPublicKey(SecOTRSessionRef session, SecOTRPublicDHKeyRef theirKey)
 114 {
 115     for(int i = 0; i < kOTRKeyCacheSize; ++i)
 116     {
 117         if (0 == timingsafe_bcmp(session->_keyCache[i]._publicKeyHash, SecPDHKGetHash(theirKey), CCSHA1_OUTPUT_SIZE)) {
 118             CFDataAppendBytes(session->_macKeysToExpose, session->_keyCache[i]._receiveMacKey, sizeof(session->_keyCache[i]._receiveMacKey));
 119
 120             bzero(&session->_keyCache[i], sizeof(session->_keyCache[i]));
 121         }
 122     }
 123 }
 124
 125 static void SecOTRGenerateNewProposedKey(SecOTRSessionRef session)
 126 {
 127     SecOTRSExpireCachedKeysForFullKey(session, session->_myKey);
 128
 129     // Swap the keys so we know the current key.
 130     {
 131         SecOTRFullDHKeyRef oldKey = session->_myKey;
 132         session->_myKey = session->_myNextKey;
 133         session->_myNextKey = oldKey;
 134     }
 135
 136     // Derive a new next key by regenerating over the old key.
 137     SecFDHKNewKey(session->_myNextKey);
 138
 139     session->_keyID += 1;
 140 }
 141
 142
 143 static void SecOTRSHandleProposalAcknowledge(SecOTRSessionRef session){
 144     if(session->_missedAck){
 145         SecOTRGenerateNewProposedKey(session);
 146         session->_missedAck = false;
 147     }
 148     else{
 149         session->_receivedAck = true;
 150         SecOTRSEnableTimeToRoll(session);
 151     }
 152 }
 153
 154 static void SecOTRSRollIfTime(SecOTRSessionRef session){
 155
 156     CFAbsoluteTime now = CFAbsoluteTimeGetCurrent();
 157     CFAbsoluteTime longestTimeToRoll = now + session->_stallSeconds;
 158
 159     //in case time to roll becomes too large we're going to roll now!
 160     if(session->_timeToRoll < now || session->_timeToRoll > longestTimeToRoll){
 161         SOSOTRSRoll(session);
 162         session->_timeToRoll = 0;
 163     }
 164 }
 165
 166
 167 static OTRMessageType SecOTRSGetMessageType(CFDataRef message)
 168 {
 169     OTRMessageType type = kInvalidMessage;
 170
 171     CFDataRef decodedBytes = SecOTRCopyIncomingBytes(message);
 172
 173     const uint8_t *bytes = CFDataGetBytePtr(decodedBytes);
 174     size_t size = CFDataGetLength(decodedBytes);
 175
 176     if (noErr != ReadHeader(&bytes, &size, &type)) {
 177         uint8_t firstByte = *CFDataGetBytePtr(decodedBytes);
 178         switch (firstByte) {
 179             case kOddCompactDataMessage:
 180             case kEvenCompactDataMessage:
 181             case kOddCompactDataMessageWithHashes:
 182             case kEvenCompactDataMessageWithHashes:
 183                 type = firstByte;
 184                 break;
 185
 186             default:
 187                 break;
 188         }
 189     }
 190
 191     CFReleaseNull(decodedBytes);
 192
 193     return type;
 194 }
 195
 196 #if DEBUG
 197
 198 static CFStringRef SecOTRCacheElementCopyDescription(SecOTRCacheElement *keyCache){
 199     __block CFStringRef description = NULL;
 200     BufferPerformWithHexString(keyCache->_fullKeyHash, sizeof(keyCache->_fullKeyHash), ^(CFStringRef fullKeyHashString) {
 201         BufferPerformWithHexString(keyCache->_publicKeyHash,sizeof(keyCache->_publicKeyHash), ^(CFStringRef publicKeyHashString) {
 202             description = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("fkh: [%@], pkh: [%@], c: %llu tc: %llu"), fullKeyHashString, publicKeyHashString, keyCache->_counter, keyCache->_theirCounter);
 203         });
 204     });
 205     return description;
 206 }
 207
 208 #endif
 209 const char *SecOTRPacketTypeString(CFDataRef message)
 210 {
 211     if (!message) return "NoMessage";
 212     switch (SecOTRSGetMessageType(message)) {
 213         case kDHMessage:                        return "DHMessage (0x02)";
 214         case kDataMessage:                      return "DataMessage (0x03)";
 215         case kDHKeyMessage:                     return "DHKeyMessage (0x0A)";
 216         case kRevealSignatureMessage:           return "RevealSignatureMessage (0x11)";
 217         case kSignatureMessage:                 return "SignatureMessage (0x12)";
 218         case kEvenCompactDataMessage:           return "kEvenCompactDatamessage (0x20)";
 219         case kOddCompactDataMessage:            return "kOddCompactDataMessage (0x21)";
 220         case kEvenCompactDataMessageWithHashes: return "kEvenCompactDatamessage (0x30)";
 221         case kOddCompactDataMessageWithHashes:  return "kOddCompactDataMessage (0x31)";
 222         case kInvalidMessage:                   return "InvalidMessage (0xFF)";
 223         default:                                return "UnknownMessage";
 224     }
 225 }
 226
 227 static const char *SecOTRAuthStateString(SecOTRAuthState authState)
 228 {
 229     switch (authState) {
 230         case kIdle:                     return "Idle";
 231         case kAwaitingDHKey:            return "AwaitingDHKey";
 232         case kAwaitingRevealSignature:  return "AwaitingRevealSignature";
 233         case kAwaitingSignature:        return "AwaitingSignature";
 234         case kDone:                     return "Done";
 235         default:                        return "InvalidState";
 236     }
 237 }
 238
 239 static CF_RETURNS_RETAINED CFStringRef SecOTRSessionCopyFormatDescription(CFTypeRef cf, CFDictionaryRef formatOptions) {
 240     SecOTRSessionRef session = (SecOTRSessionRef)cf;
 241
 242     CFAbsoluteTime now = CFAbsoluteTimeGetCurrent();
 243
 244     return CFStringCreateWithFormat(kCFAllocatorDefault,NULL,CFSTR("<%s %s %s %s%s%s%s %d:%d %s%s %llu %s%s%s%s>"),
 245                                     SecOTRAuthStateString(session->_state),
 246                                     session->_compactAppleMessages ? "C" :"c",
 247                                     session->_includeHashes ? "I" : "i",
 248                                     session->_me ? "F" : "f",
 249                                     session->_them ? "P" : "p",
 250                                     session->_receivedDHMessage ? "D" : "d",
 251                                     session->_receivedDHKeyMessage ? "K" : "k",
 252                                     session->_keyID,
 253                                     session->_theirKeyID,
 254                                     session->_theirPreviousKey ? "P" : "p",
 255                                     session->_theirKey ? "T" : "t",
 256                                     session->_stallSeconds,
 257                                     session->_missedAck ? "M" : "m",
 258                                     session->_receivedAck ? "R" : "r",
 259                                     session->_stallingTheirRoll ? "S" : "s",
 260                                     (session->_timeToRoll > now && session->_timeToRoll != 0) ? "E" : "e");
 261 }
 262
 263 static void SecOTRSessionDestroy(CFTypeRef cf) {
 264     SecOTRSessionRef session = (SecOTRSessionRef)cf;
 265
 266     CFReleaseNull(session->_receivedDHMessage);
 267     CFReleaseNull(session->_receivedDHKeyMessage);
 268
 269     CFReleaseNull(session->_me);
 270     CFReleaseNull(session->_myKey);
 271     CFReleaseNull(session->_myNextKey);
 272
 273     CFReleaseNull(session->_them);
 274     CFReleaseNull(session->_theirKey);
 275     CFReleaseNull(session->_theirPreviousKey);
 276
 277     CFReleaseNull(session->_macKeysToExpose);
 278
 279     dispatch_release(session->_queue);
 280 }
 281
 282 static void SecOTRSessionResetInternal(SecOTRSessionRef session)
 283 {
 284     session->_state = kIdle;
 285
 286     CFReleaseNull(session->_receivedDHMessage);
 287     CFReleaseNull(session->_receivedDHKeyMessage);
 288
 289     session->_keyID = 0;
 290     CFReleaseNull(session->_myKey);
 291     CFReleaseNull(session->_myNextKey);
 292     //session->_myNextKey = SecOTRFullDHKCreate(kCFAllocatorDefault);
 293     session->_theirKeyID = 0;
 294     CFReleaseNull(session->_theirKey);
 295     CFReleaseNull(session->_theirPreviousKey);
 296     CFReleaseNull(session->_macKeysToExpose);
 297     session->_macKeysToExpose = CFDataCreateMutable(kCFAllocatorDefault, 0);
 298
 299     bzero(session->_keyCache, sizeof(session->_keyCache));
 300 }
 301
 302 int SecOTRSGetKeyID(SecOTRSessionRef session){
 303     return session->_keyID;
 304 }
 305
 306 int SecOTRSGetTheirKeyID(SecOTRSessionRef session){
 307     return session->_theirKeyID;
 308 }
 309
 310 void SecOTRSessionReset(SecOTRSessionRef session)
 311 {
 312     dispatch_sync_f(session->_queue, session, (dispatch_function_t) SecOTRSessionResetInternal);
 313 }
 314
 315
 316 static void SecOTRPIPerformWithSerializationString(SecOTRPublicIdentityRef id, void (^action)(CFStringRef string)) {
 317     CFMutableDataRef idData = CFDataCreateMutable(kCFAllocatorDefault, 0);
 318     SecOTRPIAppendSerialization(id, idData, NULL);
 319     CFDataPerformWithHexString(idData, action);
 320     CFReleaseNull(idData);
 321 }
 322
 323 SecOTRSessionRef SecOTRSessionCreateFromID(CFAllocatorRef allocator,
 324                                            SecOTRFullIdentityRef myID,
 325                                            SecOTRPublicIdentityRef theirID)
 326 {
 327     SecOTRSessionRef newID = CFTypeAllocate(SecOTRSession, struct _SecOTRSession, allocator);
 328
 329     (void)SecOTRGetDefaultsWriteSeconds();
 330     newID->_queue = dispatch_queue_create("OTRSession", DISPATCH_QUEUE_SERIAL);
 331
 332     newID->_me = CFRetainSafe(myID);
 333     newID->_them = CFRetainSafe(theirID);
 334     newID->_receivedDHMessage = NULL;
 335     newID->_receivedDHKeyMessage = NULL;
 336     newID->_myKey = NULL;
 337     newID->_myNextKey = NULL;
 338     newID->_theirKey = NULL;
 339     newID->_theirPreviousKey = NULL;
 340     newID->_macKeysToExpose = NULL;
 341     newID->_textOutput = false;
 342     newID->_compactAppleMessages = false;
 343     newID->_includeHashes = false;
 344
 345     newID->_timeToRoll =  0;
 346     newID->_stallingTheirRoll = false;
 347     newID->_stallSeconds = 0;
 348     newID->_missedAck = true;
 349     newID->_receivedAck = false;
 350
 351     SecOTRSessionResetInternal(newID);
 352
 353     {
 354         SecOTRPublicIdentityRef myPublicID = SecOTRPublicIdentityCopyFromPrivate(kCFAllocatorDefault, newID->_me, NULL);
 355         SecOTRPIPerformWithSerializationString(myPublicID, ^(CFStringRef myIDString) {
 356             SecOTRPIPerformWithSerializationString(newID->_them, ^(CFStringRef theirIDString) {
 357                 secnotice("otr", "%@ Creating with M: %@, T: %@", newID, myIDString, theirIDString);
 358             });
 359         });
 360         CFReleaseNull(myPublicID);
 361     }
 362
 363     return newID;
 364 }
 365
 366 SecOTRSessionRef SecOTRSessionCreateFromIDAndFlags(CFAllocatorRef allocator,
 367                                            SecOTRFullIdentityRef myID,
 368                                            SecOTRPublicIdentityRef theirID,
 369                                            uint32_t flags)
 370 {
 371
 372     uint64_t seconds = SecOTRGetDefaultsWriteSeconds();
 373
 374     SecOTRSessionRef newID = SecOTRSessionCreateFromID(allocator, myID, theirID);
 375     if (flags & kSecOTRSendTextMessages) {
 376         newID->_textOutput = true;
 377     }
 378     if (flags & kSecOTRUseAppleCustomMessageFormat) {
 379         newID->_compactAppleMessages = true;
 380     }
 381     if(flags & kSecOTRIncludeHashesInMessages)
 382     {
 383         newID->_includeHashes = true;
 384     }
 385     if(flags & kSecOTRSlowRoll)
 386     {
 387         newID->_stallSeconds = seconds;
 388     }
 389
 390     return newID;
 391 }
 392
 393 static uint64_t constant_zero = 0;
 394
 395 static bool hashIsZero(uint8_t hash[CCSHA1_OUTPUT_SIZE])
 396 {
 397     bool isZero = true;
 398     for(size_t byte = 0; isZero && byte < CCSHA1_OUTPUT_SIZE; ++byte)
 399         isZero = (0 == hash[byte]);
 400
 401     return isZero;
 402 }
 403
 404 static bool SOSOTRSCacheEntryIsEmpty(SecOTRCacheElement *element)
 405 {
 406     return hashIsZero(element->_fullKeyHash) && hashIsZero(element->_publicKeyHash);
 407 }
 408
 409 #if DEBUG
 410
 411 static void WithCacheDescription(SecOTRSessionRef session, void (^operation)(CFStringRef cacheDescription)) {
 412     CFStringRef description = NULL;
 413
 414     CFStringRef keyCache0Description = SecOTRCacheElementCopyDescription(&session->_keyCache[0]);
 415     CFStringRef keyCache1Description = SecOTRCacheElementCopyDescription(&session->_keyCache[1]);
 416     CFStringRef keyCache2Description = SecOTRCacheElementCopyDescription(&session->_keyCache[2]);
 417     CFStringRef keyCache3Description = SecOTRCacheElementCopyDescription(&session->_keyCache[3]);
 418
 419     description = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("{%@, %@, %@, %@}"), keyCache0Description, keyCache1Description, keyCache2Description, keyCache3Description);
 420
 421     operation(description);
 422
 423     CFReleaseNull(keyCache0Description);
 424     CFReleaseNull(keyCache1Description);
 425     CFReleaseNull(keyCache2Description);
 426     CFReleaseNull(keyCache3Description);
 427     CFReleaseNull(description);
 428 }
 429
 430 #endif
 431
 432 static void SecOTRSFindKeysForMessage(SecOTRSessionRef session,
 433                                       SecOTRFullDHKeyRef myKey,
 434                                       SecOTRPublicDHKeyRef theirKey,
 435                                       bool sending,
 436                                       uint8_t** messageKey, uint8_t** macKey, uint64_t **counter)
 437 {
 438     SecOTRCacheElement* emptyKeys = NULL;
 439     SecOTRCacheElement* cachedKeys = NULL;
 440 #if DEBUG
 441     int emptyPosition = kOTRKeyCacheSize;
 442 #endif
 443
 444     if ((NULL == myKey) || (NULL == theirKey)) {
 445         if (messageKey)
 446             *messageKey = NULL;
 447         if (macKey)
 448             *macKey = NULL;
 449         if (counter)
 450             *counter = &constant_zero;
 451
 452         return;
 453     }
 454
 455     for(int i = 0; i < kOTRKeyCacheSize; ++i)
 456     {
 457         if (0 == timingsafe_bcmp(session->_keyCache[i]._fullKeyHash, SecFDHKGetHash(myKey), CCSHA1_OUTPUT_SIZE)
 458          && (0 == timingsafe_bcmp(session->_keyCache[i]._publicKeyHash, SecPDHKGetHash(theirKey), CCSHA1_OUTPUT_SIZE))) {
 459             cachedKeys = &session->_keyCache[i];
 460 #if DEBUG
 461             secdebug("OTR","session@[%p] found key match: mk: %@, tk: %@", session, myKey, theirKey);
 462 #endif
 463             break;
 464         }
 465
 466         if (emptyKeys == NULL && SOSOTRSCacheEntryIsEmpty(&(session->_keyCache[i]))) {
 467 #if DEBUG
 468             emptyPosition = i;
 469 #endif
 470
 471             emptyKeys = &session->_keyCache[i];
 472         }
 473     }
 474
 475     if (cachedKeys == NULL) {
 476         if (emptyKeys == NULL) {
 477 #if DEBUG
 478             WithCacheDescription(session, ^(CFStringRef cacheDescription) {
 479                 secdebug("OTR","session@[%p] Cache miss, spooky for mk: %@, tk: %@ cache: %@", session, myKey, theirKey, cacheDescription);
 480             });
 481             emptyPosition = 0;
 482 #endif
 483
 484             emptyKeys = &session->_keyCache[0];
 485
 486         }
 487         assert(emptyKeys);
 488
 489         // Fill in the entry.
 490         memcpy(emptyKeys->_fullKeyHash, SecFDHKGetHash(myKey), CCSHA1_OUTPUT_SIZE);
 491         memcpy(emptyKeys->_publicKeyHash, SecPDHKGetHash(theirKey), CCSHA1_OUTPUT_SIZE);
 492
 493         emptyKeys->_counter = 0;
 494         emptyKeys->_theirCounter = 0;
 495
 496         SecOTRDHKGenerateOTRKeys(myKey, theirKey,
 497                               emptyKeys->_sendEncryptionKey, emptyKeys->_sendMacKey,
 498                               emptyKeys->_receiveEncryptionKey, emptyKeys->_receiveMacKey);
 499
 500         cachedKeys = emptyKeys;
 501 #if DEBUG
 502         WithCacheDescription(session, ^(CFStringRef cacheDescription) {
 503             secdebug("OTR","mk %@, th: %@ session@[%p] new key cache state added key@[%d]: %@", myKey, theirKey, session, emptyPosition, cacheDescription);
 504         });
 505 #endif
 506
 507     }
 508
 509     if (messageKey)
 510         *messageKey = sending ? cachedKeys->_sendEncryptionKey : cachedKeys->_receiveEncryptionKey;
 511     if (macKey)
 512         *macKey = sending ? cachedKeys->_sendMacKey : cachedKeys->_receiveMacKey;
 513     if (counter)
 514         *counter = sending ? &cachedKeys->_counter : &cachedKeys->_theirCounter;
 515 }
 516
 517 SecOTRSessionRef SecOTRSessionCreateFromData(CFAllocatorRef allocator, CFDataRef data)
 518 {
 519     if (data == NULL)
 520         return NULL;
 521
 522     SecOTRSessionRef result = NULL;
 523     SecOTRSessionRef session = CFTypeAllocate(SecOTRSession, struct _SecOTRSession, allocator);
 524
 525     uint8_t numberOfKeys;
 526     uint64_t timeToRoll;
 527
 528     const uint8_t *bytes = CFDataGetBytePtr(data);
 529     size_t size = (size_t)CFDataGetLength(data);
 530
 531     (void)SecOTRGetDefaultsWriteSeconds();
 532
 533     session->_queue = dispatch_queue_create("OTRSession", DISPATCH_QUEUE_SERIAL);
 534
 535     session->_me = NULL;
 536     session->_them = NULL;
 537     session->_myKey = NULL;
 538     session->_myNextKey = NULL;
 539     session->_theirKey = NULL;
 540     session->_theirPreviousKey = NULL;
 541     session->_receivedDHMessage = NULL;
 542     session->_receivedDHKeyMessage = NULL;
 543     session->_textOutput = false;
 544     session->_compactAppleMessages = false;
 545     session->_timeToRoll =  0;
 546     session->_stallingTheirRoll = false;
 547     session->_stallSeconds = 0;
 548     session->_missedAck = true;
 549     session->_receivedAck = false;
 550
 551     bzero(session->_keyCache, sizeof(session->_keyCache));
 552
 553     uint8_t version;
 554     require_noerr(ReadByte(&bytes, &size, &version), fail);
 555     require(version <= 6, fail);
 556
 557     require_noerr(ReadLong(&bytes, &size, &session->_state), fail);
 558     session->_me = SecOTRFullIdentityCreateFromBytes(kCFAllocatorDefault, &bytes, &size, NULL);
 559     require(session->_me != NULL, fail);
 560     session->_them = SecOTRPublicIdentityCreateFromBytes(kCFAllocatorDefault, &bytes, &size, NULL);
 561     require(session->_them != NULL, fail);
 562
 563     require(size > sizeof(session->_r), fail);
 564     memcpy(session->_r, bytes, sizeof(session->_r));
 565     bytes += sizeof(session->_r);
 566     size -= sizeof(session->_r);
 567
 568     {
 569         uint8_t hasMessage = false;
 570         ReadByte(&bytes, &size, &hasMessage);
 571         if (hasMessage) {
 572             session->_receivedDHMessage = CFDataCreateMutableFromOTRDATA(kCFAllocatorDefault, &bytes, &size);
 573         }
 574     }
 575
 576     if (version >= 2) {
 577         uint8_t hasMessage = false;
 578         ReadByte(&bytes, &size, &hasMessage);
 579         if (hasMessage) {
 580             session->_receivedDHKeyMessage = CFDataCreateMutableFromOTRDATA(kCFAllocatorDefault, &bytes, &size);
 581         }
 582     }
 583
 584     if (version < 3) {
 585         uint8_t ready;
 586         require_noerr(ReadByte(&bytes, &size, &ready), fail);
 587         if (ready && session->_state == kIdle)
 588             session->_state = kDone;
 589     }
 590
 591
 592     require_noerr(ReadLong(&bytes, &size, &session->_keyID), fail);
 593     if (session->_keyID > 0) {
 594         session->_myKey = SecOTRFullDHKCreateFromBytes(kCFAllocatorDefault, &bytes, &size);
 595         require(session->_myKey != NULL, fail);
 596         session->_myNextKey = SecOTRFullDHKCreateFromBytes(kCFAllocatorDefault, &bytes, &size);
 597         require(session->_myNextKey != NULL, fail);
 598     }
 599
 600
 601     require_noerr(ReadByte(&bytes, &size, &numberOfKeys), fail);
 602
 603     require_noerr(ReadLong(&bytes, &size, &session->_theirKeyID), fail);
 604     if (version < 5) {
 605         if (session->_theirKeyID > 0) {
 606             if (session->_theirKeyID > 1) {
 607                 session->_theirPreviousKey = SecOTRPublicDHKCreateFromSerialization(kCFAllocatorDefault, &bytes, &size);
 608                 require(session->_theirPreviousKey != NULL, fail);
 609             }
 610             session->_theirKey = SecOTRPublicDHKCreateFromSerialization(kCFAllocatorDefault, &bytes, &size);
 611             require(session->_theirKey != NULL, fail);
 612         }
 613     }
 614     else {
 615         if(numberOfKeys >= 1){
 616             if (numberOfKeys >= 2) {
 617                 session->_theirPreviousKey = SecOTRPublicDHKCreateFromSerialization(kCFAllocatorDefault, &bytes, &size);
 618                 require(session->_theirPreviousKey != NULL, fail);
 619             }
 620             session->_theirKey = SecOTRPublicDHKCreateFromSerialization(kCFAllocatorDefault, &bytes, &size);
 621             require(session->_theirKey != NULL, fail);
 622         }
 623     }
 624
 625
 626     uint64_t *counter;
 627     SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirKey, false, NULL, NULL, &counter);
 628     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 629     SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirKey, true, NULL, NULL, &counter);
 630     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 631     SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirPreviousKey, false, NULL, NULL, &counter);
 632     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 633     SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirPreviousKey, true, NULL, NULL, &counter);
 634     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 635     SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirKey, false, NULL, NULL, &counter);
 636     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 637     SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirKey, true, NULL, NULL, &counter);
 638     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 639     SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirPreviousKey, false, NULL, NULL, &counter);
 640     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 641     SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirPreviousKey, true, NULL, NULL, &counter);
 642     require_noerr(ReadLongLong(&bytes, &size, counter), fail);
 643
 644     session->_macKeysToExpose = CFDataCreateMutableFromOTRDATA(kCFAllocatorDefault, &bytes, &size);
 645     require(session->_macKeysToExpose != NULL, fail);
 646
 647     require_noerr(ReadByteAsBool(&bytes, &size, &session->_textOutput), fail);
 648
 649     if (version >= 4) {
 650         require_noerr(ReadByteAsBool(&bytes, &size, &session->_compactAppleMessages), fail);
 651     }
 652     if (version >= 5) {
 653         require_noerr(ReadByteAsBool(&bytes, &size, &session->_includeHashes), fail);
 654     }
 655     if (version >= 6) {
 656         require_noerr(ReadLongLong(&bytes, &size, &session->_stallSeconds), fail);
 657         require_noerr(ReadByteAsBool(&bytes, &size, &session->_stallingTheirRoll), fail);
 658         require_noerr(ReadLongLong(&bytes, &size, &timeToRoll), fail);
 659         require_noerr(ReadByteAsBool(&bytes, &size, &session->_missedAck), fail);
 660         require_noerr(ReadByteAsBool(&bytes, &size, &session->_receivedAck), fail);
 661         session->_timeToRoll = timeToRoll;
 662     }
 663     result = session;
 664     session = NULL;
 665
 666 fail:
 667     CFReleaseNull(session);
 668     return result;
 669 }
 670
 671
 672 OSStatus SecOTRSAppendSerialization(SecOTRSessionRef session, CFMutableDataRef serializeInto)
 673 {
 674     __block OSStatus result  = errSecParam;
 675
 676     require(session, abort);
 677     require(serializeInto, abort);
 678
 679     CFIndex start = CFDataGetLength(serializeInto);
 680
 681     dispatch_sync(session->_queue, ^{
 682         const uint8_t version = 6;
 683         uint8_t numberOfKeys = 0;
 684         CFDataAppendBytes(serializeInto, &version, sizeof(version));
 685
 686         AppendLong(serializeInto, session->_state);
 687
 688         result = (SecOTRFIAppendSerialization(session->_me, serializeInto, NULL)) ? errSecSuccess : errSecParam;
 689
 690         if (result == errSecSuccess) {
 691             result = (SecOTRPIAppendSerialization(session->_them, serializeInto, NULL)) ? errSecSuccess : errSecParam;
 692         }
 693
 694         if (result == errSecSuccess) {
 695             CFDataAppendBytes(serializeInto, session->_r, sizeof(session->_r));
 696
 697             if (session->_receivedDHMessage == NULL) {
 698                 AppendByte(serializeInto, 0);
 699             } else {
 700                 AppendByte(serializeInto, 1);
 701                 AppendCFDataAsDATA(serializeInto, session->_receivedDHMessage);
 702             }
 703
 704             if (session->_receivedDHKeyMessage == NULL) {
 705                 AppendByte(serializeInto, 0);
 706             } else {
 707                 AppendByte(serializeInto, 1);
 708                 AppendCFDataAsDATA(serializeInto, session->_receivedDHKeyMessage);
 709             }
 710
 711             AppendLong(serializeInto, session->_keyID);
 712             if (session->_keyID > 0) {
 713                 SecFDHKAppendSerialization(session->_myKey, serializeInto);
 714                 SecFDHKAppendSerialization(session->_myNextKey, serializeInto);
 715             }
 716
 717             if(session->_theirPreviousKey != NULL)
 718                 numberOfKeys++;
 719             if(session->_theirKey != NULL)
 720                 numberOfKeys++;
 721
 722             AppendByte(serializeInto, numberOfKeys);
 723
 724             AppendLong(serializeInto, session->_theirKeyID);
 725
 726             if (session->_theirPreviousKey != NULL)
 727                 SecPDHKAppendSerialization(session->_theirPreviousKey, serializeInto);
 728
 729             if (session->_theirKey != NULL )
 730                 SecPDHKAppendSerialization(session->_theirKey, serializeInto);
 731
 732
 733             uint64_t *counter;
 734             SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirKey, false, NULL, NULL, &counter);
 735             AppendLongLong(serializeInto, *counter);
 736             SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirKey, true, NULL, NULL, &counter);
 737             AppendLongLong(serializeInto, *counter);
 738             SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirPreviousKey, false, NULL, NULL, &counter);
 739             AppendLongLong(serializeInto, *counter);
 740             SecOTRSFindKeysForMessage(session, session->_myKey, session->_theirPreviousKey, true, NULL, NULL, &counter);
 741             AppendLongLong(serializeInto, *counter);
 742             SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirKey, false, NULL, NULL, &counter);
 743             AppendLongLong(serializeInto, *counter);
 744             SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirKey, true, NULL, NULL, &counter);
 745             AppendLongLong(serializeInto, *counter);
 746             SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirPreviousKey, false, NULL, NULL, &counter);
 747             AppendLongLong(serializeInto, *counter);
 748             SecOTRSFindKeysForMessage(session, session->_myNextKey, session->_theirPreviousKey, true, NULL, NULL, &counter);
 749             AppendLongLong(serializeInto, *counter);
 750
 751             AppendCFDataAsDATA(serializeInto, session->_macKeysToExpose);
 752
 753             AppendByte(serializeInto, session->_textOutput ? 1 : 0);
 754             AppendByte(serializeInto, session->_compactAppleMessages ? 1 : 0);
 755             AppendByte(serializeInto, session->_includeHashes ? 1 : 0);
 756
 757             AppendLongLong(serializeInto, session->_stallSeconds ? session->_stallSeconds : constant_zero);
 758
 759             AppendByte(serializeInto, session->_stallingTheirRoll ? 1 : 0);
 760             AppendLongLong(serializeInto, (uint64_t)session->_timeToRoll);
 761             AppendByte(serializeInto, session->_missedAck ? 1 : 0);
 762             AppendByte(serializeInto, session->_receivedAck ? 1 : 0);
 763
 764         }
 765     });
 766
 767     if (result != errSecSuccess)
 768         CFDataSetLength(serializeInto, start);
 769
 770 abort:
 771     return result;
 772 }
 773
 774
 775 bool SecOTRSIsForKeys(SecOTRSessionRef session, SecKeyRef myPublic, SecKeyRef theirPublic)
 776 {
 777     __block bool isForKeys = false;
 778
 779     dispatch_sync(session->_queue, ^{
 780         isForKeys = SecOTRFICompareToPublicKey(session->_me, myPublic) &&
 781                     SecOTRPICompareToPublicKey(session->_them, theirPublic);
 782     });
 783
 784     return isForKeys;
 785 }
 786
 787 bool SecOTRSGetIsReadyForMessages(SecOTRSessionRef session)
 788 {
 789     __block bool result;
 790
 791     dispatch_sync(session->_queue, ^{ result = session->_state == kDone; });
 792
 793     return result;
 794 }
 795
 796 bool SecOTRSGetIsIdle(SecOTRSessionRef session)
 797 {
 798     __block bool result;
 799
 800     dispatch_sync(session->_queue, ^{ result = session->_state == kIdle; });
 801
 802     return result;
 803 }
 804
 805 static void SecOTRSPrecalculateForPair(SecOTRSessionRef session,
 806                                        SecOTRFullDHKeyRef myKey,
 807                                        SecOTRPublicDHKeyRef theirKey)
 808 {
 809     if (myKey == NULL || theirKey == NULL)
 810         return;
 811
 812     SecOTRSFindKeysForMessage(session, myKey, theirKey, true, NULL, NULL, NULL);
 813     SecOTRSFindKeysForMessage(session, myKey, theirKey, false, NULL, NULL, NULL);
 814 }
 815
 816 static void SecOTRSPrecalculateKeysInternal(SecOTRSessionRef session)
 817 {
 818     SecOTRSPrecalculateForPair(session, session->_myKey, session->_theirKey);
 819     SecOTRSPrecalculateForPair(session, session->_myNextKey, session->_theirKey);
 820     SecOTRSPrecalculateForPair(session, session->_myKey, session->_theirPreviousKey);
 821     SecOTRSPrecalculateForPair(session, session->_myNextKey, session->_theirPreviousKey);
 822 }
 823
 824 static void SecOTRSPrecalculateNextKeysInternal(SecOTRSessionRef session)
 825 {
 826     SecOTRSPrecalculateForPair(session, session->_myKey, session->_theirKey);
 827 }
 828
 829 void SecOTRSPrecalculateKeys(SecOTRSessionRef session)
 830 {
 831     dispatch_sync_f(session->_queue, session, (dispatch_function_t) SecOTRSPrecalculateKeysInternal);
 832 }
 833
 834 enum SecOTRSMessageKind SecOTRSGetMessageKind(SecOTRSessionRef session, CFDataRef message)
 835 {
 836     OTRMessageType type = SecOTRSGetMessageType(message);
 837
 838     enum SecOTRSMessageKind kind;
 839
 840     switch (type) {
 841         case kDataMessage:
 842         case kEvenCompactDataMessage:
 843         case kOddCompactDataMessage:
 844         case kEvenCompactDataMessageWithHashes:
 845         case kOddCompactDataMessageWithHashes:
 846             kind = kOTRDataPacket;
 847             break;
 848         case kDHMessage:
 849         case kDHKeyMessage:
 850         case kRevealSignatureMessage:
 851         case kSignatureMessage:
 852             kind = kOTRNegotiationPacket;
 853             break;
 854         case kInvalidMessage:
 855         default:
 856             kind = kOTRUnknownPacket;
 857             break;
 858     }
 859
 860     return kind;
 861 }
 862
 863 static OSStatus SecOTRSSignAndProtectRaw_locked(SecOTRSessionRef session,
 864                                                 CFDataRef sourceMessage, CFMutableDataRef destinationMessage,
 865                                                 uint8_t* messageKey, uint8_t* macKey, uint64_t* counter, uint32_t theirKeyID,  SecOTRPublicDHKeyRef theirKey)
 866 {
 867     CFIndex start = CFDataGetLength(destinationMessage);
 868
 869     AppendHeader(destinationMessage, kDataMessage);
 870     AppendByte(destinationMessage, 0); // Flags, all zero
 871
 872     AppendLong(destinationMessage, session->_keyID);
 873     AppendLong(destinationMessage, theirKeyID);
 874     SecFDHKAppendPublicSerialization(session->_myNextKey, destinationMessage);
 875     AppendLongLong(destinationMessage, ++*counter);
 876
 877     CFIndex sourceSize = CFDataGetLength(sourceMessage);
 878     assert(((unsigned long)sourceSize)<=UINT32_MAX); /* this is correct as long as CFIndex is a signed long */
 879     AppendLong(destinationMessage, (uint32_t)sourceSize);
 880     uint8_t* encryptedDataPointer = CFDataIncreaseLengthAndGetMutableBytes(destinationMessage, sourceSize);
 881     AES_CTR_HighHalf_Transform(kOTRMessageKeyBytes, messageKey,
 882                                *counter,
 883                                (size_t)sourceSize, CFDataGetBytePtr(sourceMessage),
 884                                encryptedDataPointer);
 885
 886     CFIndex macedContentsSize = CFDataGetLength(destinationMessage) - start;
 887     CFIndex macSize = CCSHA1_OUTPUT_SIZE;
 888     uint8_t* macDataPointer = CFDataIncreaseLengthAndGetMutableBytes(destinationMessage, macSize);
 889
 890     cchmac(ccsha1_di(),
 891            kOTRMessageMacKeyBytes, macKey,
 892            macedContentsSize, CFDataGetBytePtr(destinationMessage) + start,
 893            macDataPointer);
 894
 895     CFDataAppend(destinationMessage, session->_macKeysToExpose);
 896
 897     return errSecSuccess;
 898 }
 899
 900 const size_t kCompactMessageMACSize = 16;
 901
 902 static OSStatus SecOTRSSignAndProtectCompact_locked(SecOTRSessionRef session,
 903                                                     CFDataRef sourceMessage, CFMutableDataRef destinationMessage,
 904                                                     uint8_t* messageKey, uint8_t* macKey, uint64_t* counter, uint32_t theirKeyID, SecOTRPublicDHKeyRef theirKey)
 905 {
 906     CFIndex start = CFDataGetLength(destinationMessage);
 907     bool sendHashes = session->_includeHashes;
 908
 909     const uint8_t messageType = sendHashes ? ((theirKeyID & 0x1) ? kOddCompactDataMessageWithHashes : kEvenCompactDataMessageWithHashes)
 910                                            : ((theirKeyID & 0x1) ? kOddCompactDataMessage           : kEvenCompactDataMessage);
 911
 912     AppendByte(destinationMessage, messageType);
 913
 914     SecFDHKAppendCompactPublicSerialization(session->_myNextKey, destinationMessage);
 915     AppendLongLongCompact(destinationMessage, ++*counter);
 916
 917     CFIndex sourceSize = CFDataGetLength(sourceMessage);
 918     assert(((unsigned long)sourceSize)<=UINT32_MAX); /* this is correct as long as CFIndex is a signed long */
 919     uint8_t* encryptedDataPointer = CFDataIncreaseLengthAndGetMutableBytes(destinationMessage, sourceSize);
 920     AES_CTR_HighHalf_Transform(kOTRMessageKeyBytes, messageKey,
 921                                *counter,
 922                                (size_t)sourceSize, CFDataGetBytePtr(sourceMessage),
 923                                encryptedDataPointer);
 924
 925     if (sendHashes) {
 926         uint8_t *senderHashPtr = CFDataIncreaseLengthAndGetMutableBytes(destinationMessage, kSecDHKHashSize);
 927
 928         memcpy(senderHashPtr, SecFDHKGetHash(session->_myKey), kSecDHKHashSize);
 929
 930         uint8_t *receiverHashPtr = CFDataIncreaseLengthAndGetMutableBytes(destinationMessage, kSecDHKHashSize);
 931
 932         memcpy(receiverHashPtr, SecPDHKGetHash(theirKey), kSecDHKHashSize);
 933     }
 934
 935
 936     CFIndex macedContentsSize = CFDataGetLength(destinationMessage) - start;
 937     CFIndex macSize = CCSHA1_OUTPUT_SIZE;
 938     uint8_t mac[macSize];
 939     cchmac(ccsha1_di(),
 940            kOTRMessageMacKeyBytes, macKey,
 941            macedContentsSize, CFDataGetBytePtr(destinationMessage) + start,
 942            mac);
 943
 944     CFDataAppendBytes(destinationMessage, mac, kCompactMessageMACSize);
 945
 946     return errSecSuccess;
 947 }
 948
 949 OSStatus SecOTRSSignAndProtectMessage(SecOTRSessionRef session,
 950                                       CFDataRef sourceMessage,
 951                                       CFMutableDataRef protectedMessage)
 952 {
 953     __block OSStatus result = errSecParam;
 954
 955     require(session, abort);
 956     require(sourceMessage, abort);
 957     require(protectedMessage, abort);
 958
 959     if(session->_state != kDone){
 960         secdebug("OTR", "Cannot sign and protect messages, we are not done negotiating sesion[%p]", session);
 961         require_quiet( session->_state == kDone, abort);
 962     }
 963
 964     dispatch_sync(session->_queue, ^{
 965         if (session->_myKey == NULL ||
 966             session->_theirKey == NULL) {
 967             return;
 968         }
 969
 970         uint8_t *messageKey;
 971         uint8_t *macKey;
 972         uint64_t *counter;
 973         uint32_t theirKeyID = session->_theirKeyID;
 974
 975         SecOTRPublicDHKeyRef theirKeyToUse = session->_theirKey;
 976
 977         SecOTRSRollIfTime(session);
 978
 979         if(session->_stallingTheirRoll && session->_theirPreviousKey){
 980             theirKeyToUse = session->_theirPreviousKey;
 981             theirKeyID = session->_theirKeyID - 1;
 982         }
 983
 984         SecOTRSFindKeysForMessage(session, session->_myKey, theirKeyToUse,
 985                                   true,
 986                                   &messageKey, &macKey, &counter);
 987         // The || !protectedMessage below is only here to shut the static analyzer up, the require(protectedMessage, abort) outside the block already ensures this new term is never true.
 988         CFMutableDataRef destinationMessage = session->_textOutput || !protectedMessage ? CFDataCreateMutable(kCFAllocatorDefault, 0) : CFRetainSafe(protectedMessage);
 989
 990         result = session->_compactAppleMessages ? SecOTRSSignAndProtectCompact_locked(session, sourceMessage, destinationMessage, messageKey, macKey, counter, theirKeyID, theirKeyToUse)
 991         : SecOTRSSignAndProtectRaw_locked(session, sourceMessage, destinationMessage, messageKey, macKey, counter, theirKeyID, theirKeyToUse);
 992
 993         if (result == errSecSuccess) {
 994             if (session->_textOutput) {
 995                 SecOTRPrepareOutgoingBytes(destinationMessage, protectedMessage);
 996             }
 997
 998             CFDataSetLength(session->_macKeysToExpose, 0);
 999         }
1000
1001         CFReleaseSafe(destinationMessage);
1002
1003         result = errSecSuccess;
1004     });
1005
1006 abort:
1007     return result;
1008 }
1009
1010 void SecOTRSKickTimeToRoll(SecOTRSessionRef session){
1011         session->_timeToRoll = CFAbsoluteTimeGetCurrent();
1012 }
1013
1014 static void SecOTRAcceptNewRemoteKey(SecOTRSessionRef session, SecOTRPublicDHKeyRef newKey)
1015 {
1016     if (session->_theirPreviousKey) {
1017         SecOTRSExpireCachedKeysForPublicKey(session, session->_theirPreviousKey);
1018     }
1019
1020     CFReleaseNull(session->_theirPreviousKey);
1021     session->_theirPreviousKey = session->_theirKey;
1022     session->_theirKey = CFRetainSafe(newKey);
1023     session->_stallingTheirRoll = true;
1024
1025     session->_theirKeyID += 1;
1026
1027     SecOTRSEnableTimeToRoll(session);
1028 }
1029
1030 OSStatus SecOTRSetupInitialRemoteKey(SecOTRSessionRef session, SecOTRPublicDHKeyRef CF_CONSUMED initialKey) {
1031
1032     bzero(session->_keyCache, sizeof(session->_keyCache));
1033
1034     CFReleaseNull(session->_theirPreviousKey);
1035     CFAssignRetained(session->_theirKey, initialKey);
1036     session->_theirKeyID = 1;
1037
1038     return errSecSuccess;
1039 }
1040
1041 ///
1042 /// MARK: SLOW ROLLING
1043 ///
1044
1045 void SOSOTRSRoll(SecOTRSessionRef session){
1046
1047     session->_stallingTheirRoll = false;
1048
1049     //receiving side roll
1050     if(session->_receivedAck){
1051         SecOTRGenerateNewProposedKey(session);
1052         session->_missedAck = false;
1053         session->_receivedAck = false;
1054     }
1055     else{
1056         session->_missedAck = true;
1057     }
1058 }
1059
1060 static OSStatus SecOTRVerifyAndExposeRaw_locked(SecOTRSessionRef session,
1061                                                 CFDataRef decodedBytes,
1062                                                 CFMutableDataRef exposedMessageContents)
1063 {
1064     OSStatus result = errSecDecode;
1065
1066     SecOTRPublicDHKeyRef newKey = NULL;
1067     const uint8_t* bytes;
1068     size_t  size;
1069     SecOTRFullDHKeyRef myKeyForMessage = NULL;
1070     SecOTRPublicDHKeyRef theirKeyForMessage = NULL;
1071     bytes = CFDataGetBytePtr(decodedBytes);
1072     size = CFDataGetLength(decodedBytes);
1073
1074     const uint8_t* macDataStart = bytes;
1075
1076     uint32_t theirID;
1077     uint32_t myID;
1078
1079     require_noerr_quiet(result = ReadAndVerifyHeader(&bytes, &size, kDataMessage), fail);
1080     require_action_quiet(size > 0, fail, result = errSecDecode);
1081
1082     require_noerr_quiet(result = ReadAndVerifyByte(&bytes, &size, 0), fail); // Flags, always zero
1083
1084     require_noerr_quiet(result = ReadLong(&bytes, &size, &theirID), fail);
1085
1086     require_action_quiet(theirID == session->_theirKeyID || (theirID == (session->_theirKeyID - 1) && session->_theirPreviousKey != NULL),
1087                          fail,
1088                          result = ((theirID + 1) < session->_theirKeyID) ? errSecOTRTooOld : errSecOTRIDTooNew);
1089
1090     require_noerr_quiet(result = ReadLong(&bytes, &size, &myID), fail);
1091
1092     require_action_quiet(myID == session->_keyID || (myID == session->_keyID + 1 && session->_myNextKey != NULL),
1093                          fail,
1094                          result = (myID < session->_keyID) ? errSecOTRTooOld : errSecOTRIDTooNew);
1095
1096
1097     // Choose appripriate keys for message:
1098     {
1099         uint8_t *messageKey;
1100         uint8_t *macKey;
1101         uint64_t *theirCounter;
1102
1103         myKeyForMessage = (myID == session->_keyID) ? session->_myKey : session->_myNextKey;
1104         theirKeyForMessage = (theirID == session->_theirKeyID) ? session->_theirKey : session->_theirPreviousKey;
1105
1106         SecOTRSFindKeysForMessage(session, myKeyForMessage, theirKeyForMessage, false,
1107                                   &messageKey, &macKey, &theirCounter);
1108
1109         size_t nextKeyMPISize;
1110         const uint8_t* nextKeyMPIBytes;
1111         require_noerr_quiet(result = SizeAndSkipMPI(&bytes, &size, &nextKeyMPIBytes, &nextKeyMPISize), fail);
1112
1113         uint64_t counter;
1114         require_noerr_quiet(result = ReadLongLong(&bytes, &size, &counter), fail);
1115         require_action_quiet(counter > *theirCounter, fail, result = errSecOTRTooOld);
1116
1117         size_t messageSize;
1118         const uint8_t* messageStart;
1119         require_noerr_quiet(result = SizeAndSkipDATA(&bytes, &size, &messageStart, &messageSize), fail);
1120
1121         size_t macDataSize = (bytes - macDataStart) ? (size_t)(bytes - macDataStart) : 0;
1122         uint8_t mac[CCSHA1_OUTPUT_SIZE];
1123         require_action_quiet(sizeof(mac) <= size, fail, result = errSecDecode);
1124
1125         cchmac(ccsha1_di(),
1126                kOTRMessageMacKeyBytes, macKey,
1127                macDataSize, macDataStart,
1128                mac);
1129
1130         require_noerr_action_quiet(timingsafe_bcmp(mac, bytes, sizeof(mac)), fail, result = errSecAuthFailed);
1131
1132         uint8_t* dataSpace = CFDataIncreaseLengthAndGetMutableBytes(exposedMessageContents, (CFIndex)messageSize);
1133
1134         AES_CTR_HighHalf_Transform(kOTRMessageKeyBytes, messageKey,
1135                                    counter,
1136                                    messageSize, messageStart,
1137                                    dataSpace);
1138
1139         // Everything is good, accept the meta data.
1140         *theirCounter = counter;
1141
1142         newKey = SecOTRPublicDHKCreateFromBytes(kCFAllocatorDefault, &nextKeyMPIBytes, &nextKeyMPISize);
1143     }
1144
1145     bool acceptTheirNewKey = newKey != NULL && theirID == session->_theirKeyID;
1146
1147     if (acceptTheirNewKey) {
1148         SecOTRAcceptNewRemoteKey(session, newKey);
1149     }
1150
1151     if (myID == (session->_keyID + 1)) {
1152         SecOTRSHandleProposalAcknowledge(session);
1153     }
1154
1155     SecOTRSRollIfTime(session);
1156
1157     SecOTRSPrecalculateNextKeysInternal(session);
1158
1159 fail:
1160     if(result != errSecSuccess){
1161         CFDataPerformWithHexString(decodedBytes, ^(CFStringRef decodedBytesString) {
1162             SecOTRPublicIdentityRef myPublicID = SecOTRPublicIdentityCopyFromPrivate(kCFAllocatorDefault, session->_me, NULL);
1163             SecOTRPIPerformWithSerializationString(myPublicID, ^(CFStringRef myIDString) {
1164                 SecOTRPIPerformWithSerializationString(session->_them, ^(CFStringRef theirIDString) {
1165             secnotice("OTR","session[%p] failed to decrypt, session: %@, mk: %@, mpk: %@, tpk: %@, tk: %@, chose tktu: %@", session, session,
1166                      session->_myKey, session->_myNextKey, session->_theirPreviousKey, session->_theirKey, theirKeyForMessage);
1167             secnotice("OTR","session[%p] failed to decrypt, mktu: %@, mpi: %@, tpi: %@, m: %@", session, myKeyForMessage, myIDString, theirIDString, decodedBytesString);
1168                 });
1169             });
1170             CFReleaseNull(myPublicID);
1171         });
1172     }
1173     CFReleaseNull(newKey);
1174     return result;
1175 }
1176
1177 static OSStatus SecOTRVerifyAndExposeRawCompact_locked(SecOTRSessionRef session,
1178                                                 CFDataRef decodedBytes,
1179                                                 CFMutableDataRef exposedMessageContents)
1180 {
1181     SecOTRPublicDHKeyRef theirProposal = NULL;
1182     OSStatus result = errSecDecode;
1183     const uint8_t* bytes;
1184     size_t  size;
1185     SecOTRPublicDHKeyRef theirKeyForMessage = NULL;
1186     bytes = CFDataGetBytePtr(decodedBytes);
1187     size = CFDataGetLength(decodedBytes);
1188     SecOTRFullDHKeyRef myKeyForMessage = NULL;
1189     const uint8_t* macDataStart = bytes;
1190     bool useEvenKey = false;
1191     bool useCurrentKey = false;
1192     bool sentHashes = false;
1193     uint64_t counter = 0;
1194
1195     uint8_t type_byte = 0;
1196     require_noerr_quiet(result = ReadByte(&bytes, &size, &type_byte), fail);
1197     require_action_quiet(type_byte == kOddCompactDataMessage || type_byte == kEvenCompactDataMessage
1198                          || type_byte == kOddCompactDataMessageWithHashes || type_byte == kEvenCompactDataMessageWithHashes, fail, result = errSecDecode);
1199
1200     useEvenKey = (type_byte == kEvenCompactDataMessage || type_byte == kEvenCompactDataMessageWithHashes);
1201     sentHashes = (type_byte == kOddCompactDataMessageWithHashes || type_byte == kEvenCompactDataMessageWithHashes);
1202
1203     useCurrentKey = useEvenKey ^ (session->_keyID & 1);
1204     myKeyForMessage = useCurrentKey ? session->_myKey : session->_myNextKey;
1205
1206     require_action_quiet(myKeyForMessage, fail, result = errSecDecode);
1207
1208     theirProposal = SecOTRPublicDHKCreateFromCompactSerialization(kCFAllocatorDefault, &bytes, &size);
1209
1210     require_action_quiet(theirProposal, fail, result = errSecDecode);
1211
1212     bool proposalIsNew = !CFEqualSafe(theirProposal, session->_theirKey);
1213     theirKeyForMessage = proposalIsNew ? session->_theirKey : session->_theirPreviousKey;
1214
1215     require_action_quiet(theirKeyForMessage, fail, result = errSecDecode);
1216
1217     uint8_t *messageKey;
1218     uint8_t *macKey;
1219     uint64_t *theirCounter;
1220
1221
1222     SecOTRSFindKeysForMessage(session, myKeyForMessage, theirKeyForMessage, false, &messageKey, &macKey, &theirCounter);
1223
1224     require_noerr_quiet(result = ReadLongLongCompact(&bytes, &size, &counter), fail);
1225     require_action_quiet(counter > *theirCounter, fail, result = errSecOTRTooOld);
1226
1227     size_t messageSize = size - kCompactMessageMACSize - (sentHashes ? 2 * kSecDHKHashSize : 0); // It's all message except for the MAC and maybe hashes
1228     const uint8_t* messageStart = bytes;
1229
1230     bytes += messageSize;
1231     size -= messageSize;
1232
1233     if (sentHashes) {
1234         // Sender then receiver keys
1235
1236         if (memcmp(SecPDHKGetHash(theirKeyForMessage), bytes, kSecDHKHashSize) != 0) {
1237             // Wrong sender key WTF.
1238 #if DEBUG
1239             BufferPerformWithHexString(bytes, kSecDHKHashSize, ^(CFStringRef dataString) {
1240                 secdebug("OTR","session[%p] Sender key hash doesn't match: %@ != %@", session, theirKeyForMessage, dataString);
1241             });
1242 #endif
1243         }
1244
1245         bytes += kSecDHKHashSize;
1246         size -= kSecDHKHashSize;
1247
1248         if (memcmp(SecFDHKGetHash(myKeyForMessage), bytes, kSecDHKHashSize) != 0) {
1249             // Wrong sender key WTF.
1250 #if DEBUG
1251             BufferPerformWithHexString(bytes, kSecDHKHashSize, ^(CFStringRef dataString) {
1252                 secdebug("OTR","session[%p] Receiver key hash doesn't match: %@ != %@", session, myKeyForMessage, dataString);
1253             });
1254 #endif
1255         }
1256
1257         bytes += kSecDHKHashSize;
1258         size -= kSecDHKHashSize;
1259
1260     }
1261
1262     uint8_t mac[CCSHA1_OUTPUT_SIZE];
1263     require_action_quiet(kCompactMessageMACSize == size, fail, result = errSecDecode); // require space for the mac and some bytes
1264
1265     size_t macDataSize = (size_t)(bytes - macDataStart);
1266
1267     cchmac(ccsha1_di(),
1268            kOTRMessageMacKeyBytes, macKey,
1269            macDataSize, macDataStart,
1270            mac);
1271
1272     require_noerr_action_quiet(timingsafe_bcmp(mac, bytes, kCompactMessageMACSize), fail, result = errSecAuthFailed);
1273
1274     uint8_t* dataSpace = CFDataIncreaseLengthAndGetMutableBytes(exposedMessageContents, (CFIndex)messageSize);
1275
1276     AES_CTR_HighHalf_Transform(kOTRMessageKeyBytes, messageKey,
1277                                counter,
1278                                messageSize, messageStart,
1279                                dataSpace);
1280
1281     // Everything is good, accept the meta data.
1282     *theirCounter = counter;
1283
1284     if (proposalIsNew) {
1285         SecOTRAcceptNewRemoteKey(session, theirProposal);
1286     }
1287
1288     if (!useCurrentKey) {
1289         SecOTRSHandleProposalAcknowledge(session);
1290     }
1291     SecOTRSRollIfTime(session);
1292
1293     SecOTRSPrecalculateNextKeysInternal(session);
1294
1295 fail:
1296     if(result != errSecSuccess){
1297         CFDataPerformWithHexString(decodedBytes, ^(CFStringRef decodedBytesString) {
1298             SecOTRPublicIdentityRef myPublicID = SecOTRPublicIdentityCopyFromPrivate(kCFAllocatorDefault, session->_me, NULL);
1299             SecOTRPIPerformWithSerializationString(myPublicID, ^(CFStringRef myIDString) {
1300                 SecOTRPIPerformWithSerializationString(session->_them, ^(CFStringRef theirIDString) {
1301             secnotice("OTR","session[%p] failed to decrypt, session: %@, mk: %@, mpk: %@, tpk: %@, tk: %@, chose tktu: %@", session, session,
1302                      session->_myKey, session->_myNextKey, session->_theirPreviousKey, session->_theirKey, theirKeyForMessage);
1303             secnotice("OTR","session[%p] failed to decrypt, mktu: %@, mpi: %@, tpi: %@, m: %@, tP: %@, tb: %hhx", session, myKeyForMessage, myIDString, theirIDString, decodedBytesString, theirProposal, type_byte);
1304                 });
1305             });
1306             CFReleaseNull(myPublicID);
1307         });
1308     }
1309     CFReleaseNull(theirProposal);
1310     return result;
1311 }
1312
1313
1314 OSStatus SecOTRSVerifyAndExposeMessage(SecOTRSessionRef session,
1315                                        CFDataRef incomingMessage,
1316                                        CFMutableDataRef exposedMessageContents)
1317 {
1318     __block OSStatus result = errSecParam;
1319
1320
1321     require(session, abort);
1322     require(incomingMessage, abort);
1323     require(exposedMessageContents, abort);
1324
1325     if(session->_state == kDone){
1326         dispatch_sync(session->_queue, ^{
1327             CFDataRef decodedBytes = SecOTRCopyIncomingBytes(incomingMessage);
1328
1329             OTRMessageType messageType = SecOTRSGetMessageType(decodedBytes);
1330
1331             switch (messageType) {
1332                 case kDataMessage:
1333                     result = SecOTRVerifyAndExposeRaw_locked(session, decodedBytes, exposedMessageContents);
1334                     break;
1335
1336                 case kOddCompactDataMessage:
1337                 case kEvenCompactDataMessage:
1338                 case kOddCompactDataMessageWithHashes:
1339                 case kEvenCompactDataMessageWithHashes:
1340                     result = SecOTRVerifyAndExposeRawCompact_locked(session, decodedBytes, exposedMessageContents);
1341                     break;
1342
1343                 default:
1344                     result = errSecUnsupportedFormat;
1345                     break;
1346             }
1347
1348             CFReleaseSafe(decodedBytes);
1349         });
1350     }
1351     else{
1352         secnotice("OTR", "session[%p]Cannot process message:%@, session is not done negotiating, session state: %@", session, incomingMessage, session);
1353         result = errSecOTRNotReady;
1354     }
1355 abort:
1356     return result;
1357 }
1358
1359
1360 OSStatus SecOTRSEndSession(SecOTRSessionRef session,
1361                            CFMutableDataRef messageToSend)
1362 {
1363     return errSecUnimplemented;
1364 }
1365
1366 static CFDataRef data_to_data_error_request(enum SecXPCOperation op, CFDataRef publicPeerId, CFErrorRef *error) {
1367     __block CFDataRef result = NULL;
1368     securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
1369         return SecXPCDictionarySetDataOptional(message, kSecXPCPublicPeerId, publicPeerId, error);
1370     }, ^bool(xpc_object_t response, CFErrorRef *error) {
1371         return (result = SecXPCDictionaryCopyData(response, kSecXPCKeyResult, error));
1372     });
1373     return result;
1374 }
1375
1376 static bool data_data_to_data_data_bool_error_request(enum SecXPCOperation op, CFDataRef sessionData, CFDataRef inputPacket, CFDataRef* outputSessionData, CFDataRef* outputPacket, bool *readyForMessages, CFErrorRef *error) {
1377     __block CFDataRef tempOutputSessionData = NULL;
1378     __block CFDataRef tempOutputPacket = NULL;
1379     __block bool tempReadyForMessages = false;
1380
1381     bool result = securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
1382         return SecXPCDictionarySetDataOptional(message, kSecXPCOTRSession, sessionData, error)
1383         && SecXPCDictionarySetDataOptional(message, kSecXPCData, inputPacket, error);
1384     }, ^bool(xpc_object_t response, CFErrorRef *error) {
1385         if (xpc_dictionary_get_bool(response, kSecXPCKeyResult)) {
1386             tempOutputSessionData = SecXPCDictionaryCopyData(response, kSecXPCOTRSession, error);
1387             tempOutputPacket = SecXPCDictionaryCopyData(response, kSecXPCData, error);
1388             tempReadyForMessages = xpc_dictionary_get_bool(response, kSecXPCOTRReady);
1389             return true;
1390         } else {
1391             return false;
1392         }
1393
1394     });
1395
1396     *outputSessionData = tempOutputSessionData;
1397     *outputPacket = tempOutputPacket;
1398     *readyForMessages = tempReadyForMessages;
1399
1400     return result;
1401 }
1402
1403
1404 CFDataRef SecOTRSessionCreateRemote(CFDataRef publicPeerId, CFErrorRef *error) {
1405     __block CFDataRef result;
1406     os_activity_initiate("SecOTRSessionCreateRemote", OS_ACTIVITY_FLAG_DEFAULT, ^{
1407         (void)SecOTRGetDefaultsWriteSeconds();
1408         result = SECURITYD_XPC(sec_otr_session_create_remote, data_to_data_error_request, publicPeerId, error);
1409     });
1410     return result;
1411 }
1412
1413 bool SecOTRSessionProcessPacketRemote(CFDataRef sessionData, CFDataRef inputPacket, CFDataRef* outputSessionData, CFDataRef* outputPacket, bool *readyForMessages, CFErrorRef *error) {
1414     __block bool result;
1415     os_activity_initiate("SecOTRSessionProcessPacketRemote", OS_ACTIVITY_FLAG_DEFAULT, ^{
1416         result = SECURITYD_XPC(sec_otr_session_process_packet_remote, data_data_to_data_data_bool_error_request, sessionData, inputPacket, outputSessionData, outputPacket, readyForMessages, error);
1417     });
1418     return result;
1419 }
1420