OSX/sec/Security/SecOTRPublicIdentity.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 "SecOTR.h"
  26 #include "SecOTRIdentityPriv.h"
  27 #include <utilities/SecCFWrappers.h>
  28
  29 #include <AssertMacros.h>
  30
  31 #include <CoreFoundation/CFNumber.h>
  32 #include <CoreFoundation/CFString.h>
  33 #include <CoreFoundation/CFData.h>
  34
  35 #include <Security/SecKey.h>
  36 #include <Security/SecKeyPriv.h>
  37
  38 #include <corecrypto/ccn.h>
  39 #include <corecrypto/ccec.h>
  40 #include <corecrypto/ccder.h>
  41
  42 #import <sys/syslog.h>
  43
  44 #include "SecOTRErrors.h"
  45 #include <TargetConditionals.h>
  46
  47 #include <CommonCrypto/CommonDigest.h>
  48 #include <CommonCrypto/CommonDigestSPI.h>
  49
  50 /*
  51  * Support for encoding and decoding DH parameter blocks.
  52  * Apple form encodes the reciprocal of the prime p.
  53  */
  54
  55 enum {
  56     kOTRPIDER_SigningID = 1,
  57     kOTRPIDER_SupportsHashes =3,
  58 };
  59
  60 //
  61 // SecOTRPublicIdentity implementation
  62 //
  63
  64 CFGiblisFor(SecOTRPublicIdentity);
  65
  66 static bool sAdvertiseHashes = false;
  67
  68 static CF_RETURNS_RETAINED CFStringRef SecOTRPublicIdentityCopyFormatDescription(CFTypeRef cf, CFDictionaryRef formatOptions) {
  69     SecOTRPublicIdentityRef requestor = (SecOTRPublicIdentityRef)cf;
  70    return CFStringCreateWithFormat(kCFAllocatorDefault,NULL,CFSTR("<SecOTRPublicIdentity: %p %02x%02x%02x%02x%02x%02x%02x%02x>"),
  71                                     requestor,
  72                                     requestor->hash[0], requestor->hash[1],
  73                                     requestor->hash[2], requestor->hash[3],
  74                                     requestor->hash[4], requestor->hash[5],
  75                                     requestor->hash[6], requestor->hash[7]);
  76 }
  77
  78 static void SecOTRPublicIdentityDestroy(CFTypeRef cf) {
  79     SecOTRPublicIdentityRef requestor = (SecOTRPublicIdentityRef)cf;
  80
  81     CFReleaseNull(requestor->publicSigningKey);
  82 }
  83
  84 static bool SecKeyDigestAndVerifyWithError(
  85                                            SecKeyRef           key,            /* Public key */
  86                                            const SecAsn1AlgId  *algId,         /* algorithm oid/params */
  87                                            const uint8_t       *dataToDigest,   /* signature over this data */
  88                                            size_t              dataToDigestLen,/* length of dataToDigest */
  89                                            uint8_t             *sig,                    /* signature to verify */
  90                                            size_t              sigLen,         /* length of sig */
  91                                            CFErrorRef          *error) {
  92
  93     OSStatus status = SecKeyDigestAndVerify(key, algId, dataToDigest, dataToDigestLen, sig, sigLen);
  94     require_noerr(status, fail);
  95     return true;
  96 fail:
  97     SecOTRCreateError(secOTRErrorOSError, status, CFSTR("Error verifying message. OSStatus in error code."), NULL, error);
  98     return false;
  99 }
 100
 101 static bool SecOTRPICacheHash(SecOTRPublicIdentityRef pubID, CFErrorRef *error)
 102 {
 103     bool result = false;
 104
 105     CFMutableDataRef stream = CFDataCreateMutable(NULL, 0);
 106
 107     require(SecOTRPIAppendSerialization(pubID, stream, error), fail);
 108
 109     CCDigest(kCCDigestSHA1, CFDataGetBytePtr(stream), (CC_LONG)CFDataGetLength(stream), pubID->hash);
 110
 111     result = true;
 112
 113 fail:
 114     CFReleaseSafe(stream);
 115     return result;
 116 }
 117
 118 void SecOTRAdvertiseHashes(bool advertise) {
 119     sAdvertiseHashes = advertise;
 120 }
 121
 122 bool SecOTRPICompareToPublicKey(SecOTRPublicIdentityRef pubID, SecKeyRef publicKey) {
 123     return CFEqualSafe(pubID->publicSigningKey, publicKey);
 124 }
 125
 126 SecOTRPublicIdentityRef SecOTRPublicIdentityCopyFromPrivate(CFAllocatorRef allocator, SecOTRFullIdentityRef fullID, CFErrorRef *error)
 127 {
 128     SecOTRPublicIdentityRef result = CFTypeAllocate(SecOTRPublicIdentity, struct _SecOTRPublicIdentity, allocator);
 129
 130     EnsureOTRAlgIDInited();
 131
 132     result->publicSigningKey = fullID->publicSigningKey;
 133     CFRetain(result->publicSigningKey);
 134
 135     require(SecOTRPICacheHash(result, error), fail);
 136
 137     return result;
 138
 139 fail:
 140     CFReleaseSafe(result);
 141     return NULL;
 142 }
 143
 144
 145 SecOTRPublicIdentityRef SecOTRPublicIdentityCreateFromSecKeyRef(CFAllocatorRef allocator, SecKeyRef publicKey,
 146                                                             CFErrorRef *error) {
 147     // TODO - make sure this is an appropriate key type
 148     SecOTRPublicIdentityRef result = CFTypeAllocate(SecOTRPublicIdentity, struct _SecOTRPublicIdentity, allocator);
 149     result->publicSigningKey = publicKey;
 150     CFRetain(result->publicSigningKey);
 151     require(SecOTRPICacheHash(result, error), fail);
 152     return result;
 153 fail:
 154     CFRelease(result->publicSigningKey);
 155     CFReleaseSafe(result);
 156     return NULL;
 157 }
 158
 159 typedef SecKeyRef (*SecOTRPublicKeyCreateFunction)(CFAllocatorRef allocator, const uint8_t** data, size_t* limit);
 160
 161 static SecKeyRef SecOTRCreatePublicKeyFrom(const uint8_t* keyData, size_t keyDataSize, ccder_tag tagContainingKey, SecOTRPublicKeyCreateFunction createFunction)
 162 {
 163     SecKeyRef createdKey = NULL;
 164
 165     createdKey = createFunction(kCFAllocatorDefault, &keyData, &keyDataSize);
 166
 167     require(createdKey != NULL, fail);
 168     require(keyDataSize == 0, fail);
 169
 170     return createdKey;
 171
 172 fail:
 173     CFReleaseSafe(createdKey);
 174     return NULL;
 175 }
 176
 177
 178 SecOTRPublicIdentityRef SecOTRPublicIdentityCreateFromBytes(CFAllocatorRef allocator, const uint8_t**bytes, size_t* size, CFErrorRef *error)
 179 {
 180     CFErrorRef stackedError = NULL;
 181
 182     SecOTRPublicIdentityRef newID = CFTypeAllocate(SecOTRPublicIdentity, struct _SecOTRPublicIdentity, allocator);
 183
 184     EnsureOTRAlgIDInited();
 185
 186     const uint8_t* fullSequenceEnd = *bytes + *size;
 187
 188     const uint8_t* keyData = ccder_decode_sequence_tl(&fullSequenceEnd, *bytes, fullSequenceEnd);
 189     size_t fullSize = (size_t)(fullSequenceEnd - *bytes);
 190
 191     size_t   keyDataSize;
 192     keyData = ccder_decode_tl(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SigningID, &keyDataSize, keyData, fullSequenceEnd);
 193     newID->publicSigningKey = SecOTRCreatePublicKeyFrom(keyData, keyDataSize, kOTRPIDER_SigningID, &CreateECPublicKeyFrom);
 194     require(newID->publicSigningKey != NULL, fail);
 195     keyData += keyDataSize;
 196
 197     newID->wantsHashes = (NULL != ccder_decode_tl(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SupportsHashes, &keyDataSize, keyData, fullSequenceEnd));
 198
 199     require(SecOTRPICacheHash(newID, &stackedError), fail);
 200
 201     *bytes += fullSize;
 202     *size -= fullSize;
 203
 204     return newID;
 205
 206 fail:
 207     SecOTRCreateError(secOTRErrorLocal, kSecOTRErrorCreatePublicIdentity, CFSTR("Error creating public identity from bytes"), stackedError, error);
 208     CFReleaseSafe(newID);
 209     return NULL;
 210 }
 211
 212 SecOTRPublicIdentityRef SecOTRPublicIdentityCreateFromData(CFAllocatorRef allocator, CFDataRef serializedData, CFErrorRef *error)
 213 {
 214     if (serializedData == NULL)
 215         return NULL;
 216
 217     size_t length = (size_t)CFDataGetLength(serializedData);
 218     const uint8_t* bytes = CFDataGetBytePtr(serializedData);
 219     return SecOTRPublicIdentityCreateFromBytes(allocator, &bytes, &length, error);
 220 }
 221
 222 bool SecOTRPIEqualToBytes(SecOTRPublicIdentityRef id, const uint8_t*bytes, CFIndex size)
 223 {
 224     CFDataRef dataToMatch = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, bytes, size, kCFAllocatorNull);
 225     CFMutableDataRef idStreamed = CFDataCreateMutable(kCFAllocatorDefault, 0);
 226
 227     SecOTRPIAppendSerialization(id, idStreamed, NULL);
 228
 229     bool equal = CFEqualSafe(dataToMatch, idStreamed);
 230
 231     if (!equal) {
 232         CFDataPerformWithHexString(dataToMatch, ^(CFStringRef dataToMatchString) {
 233             CFDataPerformWithHexString(idStreamed, ^(CFStringRef idStreamedString) {
 234                 secnotice("otr", "ID Comparison failed: d: %@ id: %@", dataToMatchString, idStreamedString);
 235             });
 236         });
 237     }
 238
 239     CFReleaseNull(dataToMatch);
 240     CFReleaseNull(idStreamed);
 241
 242     return equal;
 243 }
 244
 245 bool SecOTRPIEqual(SecOTRPublicIdentityRef left, SecOTRPublicIdentityRef right)
 246 {
 247     if (left == right)
 248         return true;
 249
 250     CFMutableDataRef leftData = CFDataCreateMutable(kCFAllocatorDefault, 0);
 251     CFMutableDataRef rightData = CFDataCreateMutable(kCFAllocatorDefault, 0);
 252
 253     SecOTRPIAppendSerialization(left, leftData, NULL);
 254     SecOTRPIAppendSerialization(right, rightData, NULL);
 255
 256     bool match = CFEqualSafe(leftData, rightData);
 257
 258     CFReleaseNull(leftData);
 259     CFReleaseNull(rightData);
 260
 261     return match;
 262 }
 263
 264 size_t SecOTRPISignatureSize(SecOTRPublicIdentityRef publicID)
 265 {
 266     return SecKeyGetSize(publicID->publicSigningKey, kSecKeySignatureSize);
 267 }
 268
 269 bool SecOTRPIAppendSerialization(SecOTRPublicIdentityRef publicID, CFMutableDataRef serializeInto, CFErrorRef *error)
 270 {
 271     CFIndex start = CFDataGetLength(serializeInto);
 272     CFMutableDataRef signingKeySerialized = CFDataCreateMutable(kCFAllocatorDefault, 0);
 273
 274     uint8_t sendHashes[1] = { 0xFF };
 275
 276     require_noerr(appendPublicOctetsAndSize(publicID->publicSigningKey, signingKeySerialized), fail);
 277
 278     size_t outputSize = ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 279                                      ccder_sizeof_implicit_raw_octet_string(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SigningID, (size_t)CFDataGetLength(signingKeySerialized)) +
 280                                      (sAdvertiseHashes ? ccder_sizeof_implicit_raw_octet_string(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SupportsHashes, sizeof(sendHashes)) : 0));
 281
 282     CFDataIncreaseLength(serializeInto, outputSize);
 283
 284     uint8_t *outputBuffer = CFDataGetMutableBytePtr(serializeInto) + start;
 285     uint8_t *outputBufferEnd = outputBuffer + outputSize;
 286
 287     uint8_t *result = ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, outputBufferEnd, outputBuffer,
 288                       ccder_encode_implicit_raw_octet_string(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SigningID, (size_t)CFDataGetLength(signingKeySerialized), CFDataGetBytePtr(signingKeySerialized), outputBuffer,
 289                       sAdvertiseHashes ? ccder_encode_implicit_raw_octet_string(CCDER_CONTEXT_SPECIFIC | kOTRPIDER_SupportsHashes, sizeof(sendHashes), sendHashes, outputBuffer, outputBufferEnd) : outputBufferEnd));
 290
 291     require_quiet(result == outputBuffer, fail);
 292
 293     CFReleaseSafe(signingKeySerialized);
 294
 295     return true;
 296
 297 fail:
 298     CFReleaseSafe(signingKeySerialized);
 299
 300     CFDataSetLength(serializeInto, start);
 301
 302     SecOTRCreateError(secOTRErrorLocal, kSecOTRErrorCreatePublicBytes, CFSTR("Unable to create public key bytes"), NULL, error);
 303     return false;
 304 }
 305
 306 static const uint8_t *mp_decode_forced_uint(cc_size n, cc_unit *r, const uint8_t *der, const uint8_t *der_end) {
 307     size_t len;
 308     der = ccder_decode_tl(CCDER_INTEGER, &len, der, der_end);
 309     if (der && ccn_read_uint(n, r, len, der) >= 0)
 310         return der + len;
 311
 312     return NULL;
 313 }
 314
 315 static void SecOTRPIRecreateSignature(const uint8_t *oldSignature, size_t oldSignatureSize, uint8_t **newSignature, size_t *newSignatureSize)
 316 {
 317     cc_unit r[ccec_cp_n(ccec_cp_256())], s[ccec_cp_n(ccec_cp_256())];
 318     cc_size n = ccec_cp_n(ccec_cp_256());
 319
 320     const uint8_t *oldSignatureEnd = oldSignature + oldSignatureSize;
 321
 322     oldSignature = ccder_decode_sequence_tl(&oldSignatureEnd, oldSignature, oldSignatureEnd);
 323     oldSignature = mp_decode_forced_uint(n, r, oldSignature, oldSignatureEnd);
 324     oldSignature = mp_decode_forced_uint(n, s, oldSignature, oldSignatureEnd);
 325     (void) oldSignature; // We could check for a good end, but it'll come out when we re-encode.
 326
 327     const uint8_t *outputPointer = *newSignature;
 328     uint8_t *outputEndPointer = *newSignature + *newSignatureSize;
 329
 330     *newSignature = ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, outputEndPointer, outputPointer, ccder_encode_integer(n, r, outputPointer, ccder_encode_integer(n, s, outputPointer, outputEndPointer)));
 331     long newSigSize = outputEndPointer - *newSignature;
 332     *newSignatureSize = (newSigSize >= 0) ? (size_t)newSigSize : 0;
 333 }
 334
 335 bool SecOTRPIVerifySignature(SecOTRPublicIdentityRef publicID,
 336                                 const uint8_t *dataToHash, size_t amountToHash,
 337                                 const uint8_t *signatureStart, size_t signatureSize, CFErrorRef *error)
 338 {
 339     require(signatureSize > 0, fail);
 340     require(*signatureStart == signatureSize - 1, fail);
 341     signatureSize -= 1;
 342     signatureStart += 1;
 343
 344     require(SecKeyDigestAndVerifyWithError(publicID->publicSigningKey, kOTRSignatureAlgIDPtr,
 345                                  dataToHash, amountToHash,
 346                                  (uint8_t*)signatureStart, signatureSize, NULL), fail);
 347     return true;
 348 fail: ;
 349     uint8_t *replacementSignature = malloc(signatureSize + 3);
 350     require(replacementSignature != NULL, fail2);
 351
 352     size_t replacementSignatureLen = sizeof(replacementSignature);
 353     uint8_t *replacementSignaturePtr = replacementSignature;
 354
 355     SecOTRPIRecreateSignature(signatureStart, signatureSize, &replacementSignaturePtr, &replacementSignatureLen);
 356
 357     require_action(replacementSignaturePtr, fail2, SecOTRCreateError(secOTRErrorLocal, kSecOTRErrorSignatureDidNotRecreate, CFSTR("Unable to recreate signature blob."), NULL, error));
 358
 359     require(SecKeyDigestAndVerifyWithError(publicID->publicSigningKey, kOTRSignatureAlgIDPtr,
 360                                            dataToHash, amountToHash,
 361                                            replacementSignaturePtr, replacementSignatureLen, error), fail2);
 362     free(replacementSignature);
 363     return true;
 364
 365 fail2:
 366     free(replacementSignature);
 367     return false;
 368 }
 369
 370 void SecOTRPICopyHash(SecOTRPublicIdentityRef publicID, uint8_t hash[kMPIDHashSize])
 371 {
 372     memcpy(hash, publicID->hash, kMPIDHashSize);
 373 }
 374
 375 void SecOTRPIAppendHash(SecOTRPublicIdentityRef publicID, CFMutableDataRef appendTo)
 376 {
 377     CFDataAppendBytes(appendTo, publicID->hash, sizeof(publicID->hash));
 378 }
 379
 380 bool SecOTRPICompareHash(SecOTRPublicIdentityRef publicID, const uint8_t hash[kMPIDHashSize])
 381 {
 382     return 0 == memcmp(hash, publicID->hash, kMPIDHashSize);
 383 }