keychain/ckks/CKKSSIV.m

   1 /*
   2  * Copyright (c) 2017 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 #if OCTAGON
  25
  26 #define __STDC_WANT_LIB_EXT1__ 1
  27 #include <string.h>
  28
  29 #import <AssertMacros.h>
  30 #import <Foundation/Foundation.h>
  31
  32 #import "CKKSSIV.h"
  33
  34 #include <CommonCrypto/CommonCrypto.h>
  35 #include <CommonCrypto/CommonRandom.h>
  36 #include <corecrypto/ccaes.h>
  37 #include <corecrypto/ccmode_siv.h>
  38
  39 #import "keychain/categories/NSError+UsefulConstructors.h"
  40
  41 @implementation CKKSBaseAESSIVKey
  42 - (instancetype)init {
  43     if(self = [super init]) {
  44         self->size = CKKSWrappedKeySize;
  45         [self zeroKey];
  46     }
  47     return self;
  48 }
  49 - (instancetype)initWithBytes:(uint8_t *)bytes len:(size_t)len {
  50     if(self = [super init]) {
  51         if(len <= CKKSWrappedKeySize) {
  52             self->size = len;
  53             memcpy(self->key, bytes, self->size);
  54         }
  55     }
  56     return self;
  57 }
  58 - (instancetype)initWithBase64:(NSString*)base64bytes {
  59     if(self = [super init]) {
  60         NSData* data = [[NSData alloc] initWithBase64EncodedString: base64bytes options:0];
  61
  62         if(!data) {
  63             return nil;
  64         }
  65
  66         if(data.length <= CKKSWrappedKeySize) {
  67             self->size = data.length;
  68             memcpy(self->key, data.bytes, self->size);
  69         }
  70     }
  71     return self;
  72 }
  73
  74 - (BOOL)isEqual: (id) object {
  75     if(![object isKindOfClass:[CKKSBaseAESSIVKey class]]) {
  76         return NO;
  77     }
  78
  79     CKKSBaseAESSIVKey* obj = (CKKSBaseAESSIVKey*) object;
  80     if (self->size == obj->size && 0 == memcmp(self->key, obj->key, self->size)) {
  81         return YES;
  82     } else {
  83         return NO;
  84     }
  85 }
  86
  87 - (void)dealloc {
  88     [self zeroKey];
  89 }
  90
  91 - (void)zeroKey {
  92     memset_s(self->key, self->size, 0x00, CKKSWrappedKeySize);
  93 }
  94
  95 - (instancetype)copyWithZone:(NSZone *)zone {
  96     return [[[self class] allocWithZone:zone] initWithBytes:self->key len:self->size];
  97 }
  98
  99 @end
 100
 101 @implementation CKKSWrappedAESSIVKey
 102 - (instancetype)init {
 103     if(self = [super init]) {
 104         self->size = CKKSWrappedKeySize;
 105     }
 106     return self;
 107 }
 108 - (instancetype)initWithBytes:(uint8_t *)bytes len:(size_t)len {
 109     if(len != CKKSWrappedKeySize) {
 110         @throw [NSException
 111                 exceptionWithName:@"WrongKeySizeException"
 112                 reason:[NSString stringWithFormat: @"length (%lu) was not %d", (unsigned long)len, CKKSWrappedKeySize]
 113                 userInfo:nil];
 114     }
 115     if(self = [super initWithBytes: bytes len: len]) {
 116     }
 117     return self;
 118 }
 119 - (instancetype)initWithBase64:(NSString*)base64bytes {
 120     if(self = [super initWithBase64: base64bytes]) {
 121         if(self->size != CKKSWrappedKeySize) {
 122             @throw [NSException
 123                     exceptionWithName:@"WrongKeySizeException"
 124                     reason:[NSString stringWithFormat: @"length (%lu) was not %d", (unsigned long)self->size, CKKSWrappedKeySize]
 125                     userInfo:nil];
 126         }
 127     }
 128     return self;
 129 }
 130 - (instancetype)initWithData: (NSData*) data {
 131     if(data.length != CKKSWrappedKeySize) {
 132         @throw [NSException
 133                 exceptionWithName:@"WrongKeySizeException"
 134                 reason:[NSString stringWithFormat: @"length (%lu) was not %d", (unsigned long) data.length, CKKSWrappedKeySize]
 135                 userInfo:nil];
 136     }
 137     if(self = [super initWithBytes: (uint8_t*) data.bytes len: data.length]) {
 138     }
 139     return self;
 140 }
 141 - (NSData*) wrappedData {
 142     return [[NSData alloc] initWithBytes:self->key length:self->size];
 143 }
 144 - (NSString*) base64WrappedKey {
 145     return [[self wrappedData] base64EncodedStringWithOptions:0];
 146 }
 147
 148 @end
 149
 150 @implementation CKKSAESSIVKey
 151 - (instancetype)init {
 152     if(self = [super init]) {
 153         self->size = CKKSKeySize;
 154     }
 155     return self;
 156 }
 157 - (instancetype)initWithBytes:(uint8_t *)bytes len:(size_t)len {
 158     if(len != CKKSKeySize) {
 159         @throw [NSException
 160                 exceptionWithName:@"WrongKeySizeException"
 161                 reason:[NSString stringWithFormat: @"length (%lu) was not %d", (unsigned long)len, CKKSKeySize]
 162                 userInfo:nil];
 163     }
 164     if(self = [super initWithBytes: bytes len: len]) {
 165     }
 166     return self;
 167 }
 168 - (instancetype)initWithBase64:(NSString*)base64bytes {
 169     if(self = [super initWithBase64: base64bytes]) {
 170         if(self->size != CKKSKeySize) {
 171             @throw [NSException
 172                     exceptionWithName:@"WrongKeySizeException"
 173                     reason:[NSString stringWithFormat: @"length (%lu) was not %d", (unsigned long)self->size, CKKSKeySize]
 174                     userInfo:nil];
 175         }
 176     }
 177     return self;
 178 }
 179
 180 + (instancetype)randomKey {
 181     CKKSAESSIVKey* key = [[CKKSAESSIVKey alloc] init];
 182
 183     CCRNGStatus status = CCRandomGenerateBytes(key->key, key->size);
 184     if(status != kCCSuccess) {
 185         @throw [NSException
 186                 exceptionWithName:@"randomnessException"
 187                 reason:[NSString stringWithFormat: @"CCRandomGenerateBytes failed with %d", status]
 188                 userInfo:nil];
 189     }
 190
 191     return key;
 192 }
 193
 194 - (CKKSWrappedAESSIVKey*)wrapAESKey: (CKKSAESSIVKey*) keyToWrap error: (NSError * __autoreleasing *) error {
 195     NSError* localerror = nil;
 196     bool success = false;
 197
 198     if(!keyToWrap) {
 199         localerror = [NSError errorWithDomain:@"securityd"
 200                                          code:errSecParam
 201                                   description:@"No key given"];
 202         if(error) {
 203             *error = localerror;
 204         }
 205         return nil;
 206     }
 207
 208     CKKSWrappedAESSIVKey* wrappedKey = nil;
 209     uint8_t buffer[CKKSWrappedKeySize] = {};
 210
 211     size_t ciphertextLength = ccsiv_ciphertext_size(ccaes_siv_encrypt_mode(), CKKSKeySize);
 212     require_action_quiet(ciphertextLength == CKKSWrappedKeySize, out, localerror = [NSError errorWithDomain:@"securityd"
 213                                                                                                        code:errSecParam
 214                                                                                                    userInfo:@{NSLocalizedDescriptionKey: @"wrapped key size does not match key size"}]);
 215
 216     success = [self doSIV: ccaes_siv_encrypt_mode()
 217                     nonce: nil
 218                      text: [[NSData alloc] initWithBytesNoCopy: (void*) (keyToWrap->key) length: keyToWrap->size freeWhenDone: NO]
 219                    buffer: buffer bufferLength: sizeof(buffer)
 220         authenticatedData: nil
 221                     error: error];
 222     require_quiet(success, out);
 223
 224     wrappedKey = [[CKKSWrappedAESSIVKey alloc] initWithBytes:buffer len:sizeof(buffer)];
 225 out:
 226     memset_s(buffer, sizeof(buffer), 0x00, CKKSKeySize);
 227     if(error && localerror != nil) {
 228         *error = localerror;
 229     }
 230     return wrappedKey;
 231 }
 232
 233 - (CKKSAESSIVKey*)unwrapAESKey: (CKKSWrappedAESSIVKey*) keyToUnwrap error: (NSError * __autoreleasing *) error {
 234     NSError* localerror = nil;
 235     bool success = false;
 236
 237     CKKSAESSIVKey* unwrappedKey = nil;
 238     uint8_t buffer[CKKSKeySize] = {};
 239
 240     size_t plaintextLength = ccsiv_plaintext_size(ccaes_siv_decrypt_mode(), CKKSWrappedKeySize);
 241     require_action_quiet(plaintextLength == CKKSKeySize, out, localerror = [NSError errorWithDomain:@"securityd"
 242                                                                                                code:errSecParam
 243                                                                                            userInfo:@{NSLocalizedDescriptionKey: @"unwrapped key size does not match key size"}]);
 244
 245     success = [self doSIV: ccaes_siv_decrypt_mode()
 246                     nonce: nil
 247                      text: [[NSData alloc] initWithBytesNoCopy: (void*) (keyToUnwrap->key) length: keyToUnwrap->size freeWhenDone: NO]
 248                    buffer: buffer bufferLength:sizeof(buffer)
 249         authenticatedData: nil
 250                     error: error];
 251
 252     require_quiet(success, out);
 253
 254     unwrappedKey = [[CKKSAESSIVKey alloc] initWithBytes: buffer len:sizeof(buffer)];
 255 out:
 256     memset_s(buffer, sizeof(buffer), 0x00, CKKSKeySize);
 257     if(error && localerror != nil) {
 258         *error = localerror;
 259     }
 260     return unwrappedKey;
 261 }
 262
 263
 264 - (NSData*)encryptData: (NSData*) plaintext authenticatedData: (NSDictionary<NSString*, NSData*>*) ad error: (NSError * __autoreleasing *) error {
 265     size_t nonceLength = (128/8);
 266     size_t ciphertextLength = 0;
 267
 268     NSMutableData* buffer = nil;
 269     NSMutableData* nonce = nil;
 270
 271     bool success = false;
 272
 273     const struct ccmode_siv* mode = ccaes_siv_encrypt_mode();
 274
 275     // alloc space for nonce and ciphertext.
 276     nonce = [[NSMutableData alloc] initWithLength: nonceLength];
 277     CCRNGStatus status = CCRandomGenerateBytes(nonce.mutableBytes, nonce.length);
 278     if(status != kCCSuccess) {
 279         if(error) {
 280             *error = [NSError errorWithDomain:@"CommonCrypto"
 281                                          code:status
 282                                      userInfo:@{NSLocalizedDescriptionKey: @"IV generation failed"}];
 283         }
 284         return nil;
 285     }
 286
 287     ciphertextLength = ccsiv_ciphertext_size(mode, plaintext.length);
 288     buffer = [[NSMutableData alloc] initWithLength: ciphertextLength];
 289
 290     success = [self doSIV: mode
 291                     nonce: nonce
 292                      text: plaintext
 293                    buffer: buffer.mutableBytes
 294              bufferLength: buffer.length
 295         authenticatedData: ad error: error];
 296
 297     if(!success) {
 298         return nil;
 299     }
 300
 301     NSMutableData* ret = [[NSMutableData alloc] init];
 302     [ret appendData: nonce];
 303     [ret appendData: buffer];
 304     return ret;
 305 }
 306
 307 - (NSData*)decryptData: (NSData*) ciphertext authenticatedData: (NSDictionary<NSString*, NSData*>*) ad error: (NSError * __autoreleasing *) error {
 308     size_t nonceLength = (128/8);
 309     size_t ciphertextLength = 0;
 310     size_t plaintextLength = 0;
 311
 312     NSMutableData* plaintext = nil;
 313     NSData* nonce = nil;
 314     NSData* text = nil;
 315
 316     bool success = false;
 317
 318     const struct ccmode_siv* mode = ccaes_siv_decrypt_mode();
 319
 320     // compute sizes.
 321     nonceLength = (128/8);
 322     if(ciphertext.length <= nonceLength) {
 323         if(error) {
 324             *error = [NSError errorWithDomain:@"securityd"
 325                                          code:4
 326                                      userInfo:@{NSLocalizedDescriptionKey: @"ciphertext too short"}];
 327         }
 328         return nil;
 329     }
 330
 331     ciphertextLength = ciphertext.length - (nonceLength);
 332
 333     // pointer arithmetic. tsk tsk.
 334     nonce = [[NSData alloc] initWithBytesNoCopy: (void*) ciphertext.bytes length: nonceLength freeWhenDone: NO];
 335     text = [[NSData alloc] initWithBytesNoCopy: (void*) (ciphertext.bytes + nonceLength) length: ciphertextLength freeWhenDone: NO];
 336
 337     // alloc space for plaintext
 338     plaintextLength = ccsiv_plaintext_size(mode, ciphertextLength);
 339     plaintext = [[NSMutableData alloc] initWithLength: plaintextLength];
 340
 341     success = [self doSIV: mode
 342                     nonce: nonce
 343                      text: text
 344                    buffer: plaintext.mutableBytes
 345              bufferLength: plaintext.length
 346         authenticatedData: ad error: error];
 347
 348     if(!success) {
 349         return nil;
 350     }
 351
 352     return plaintext;
 353 }
 354
 355 // Does NOT check buffer size. Make sure you get it right for the mode you're requesting!
 356 - (bool)doSIV: (const struct ccmode_siv*) mode nonce: (NSData*) nonce text: (NSData*) text buffer: (uint8_t*) buffer bufferLength: (size_t) bufferLength authenticatedData: (NSDictionary<NSString*, NSData*>*) ad error: (NSError * __autoreleasing *) error {
 357
 358     NSArray<NSString*>* adKeys = nil;
 359     NSError* localerror = nil;
 360     int status = 0;
 361
 362     ccsiv_ctx_decl(mode->size, ctx);
 363
 364     require_action_quiet(mode, out, localerror = [NSError errorWithDomain:@"securityd"
 365                                                                      code:1
 366                                                                  userInfo:@{NSLocalizedDescriptionKey: @"no mode given"}]);
 367
 368     status = ccsiv_init(mode, ctx, self->size, self->key);
 369     require_action_quiet(status == 0, out, localerror = [NSError errorWithDomain:@"corecrypto"
 370                                                                             code:status
 371                                                                         userInfo:@{NSLocalizedDescriptionKey: @"could not ccsiv_init"}]);
 372
 373     if(nonce) {
 374         status = ccsiv_set_nonce(mode, ctx, nonce.length, nonce.bytes);
 375         require_action_quiet(status == 0, out, localerror = [NSError errorWithDomain:@"corecrypto"
 376                                                                                 code:status
 377                                                                             userInfo:@{NSLocalizedDescriptionKey: @"could not ccsiv_set_nonce"}]);
 378     }
 379
 380     // Add authenticated data, sorted by Key Order
 381     adKeys = [[ad allKeys] sortedArrayUsingSelector:@selector(compare:)];
 382     for(NSString* adKey in adKeys) {
 383         NSData* adValue = [ad objectForKey: adKey];
 384         status = ccsiv_aad(mode, ctx, adValue.length, adValue.bytes);
 385         require_action_quiet(status == 0, out, localerror = [NSError errorWithDomain:@"corecrypto"
 386                                                                                 code:status
 387                                                                             userInfo:@{NSLocalizedDescriptionKey: @"could not ccsiv_aad"}]);
 388     }
 389
 390     // Actually go.
 391     status = ccsiv_crypt(mode, ctx, text.length, text.bytes, buffer);
 392     require_action_quiet(status == 0, out, localerror = [NSError errorWithDomain:@"corecrypto"
 393                                                                             code:status
 394                                                                         userInfo:@{NSLocalizedDescriptionKey: @"could not ccsiv_crypt"}]);
 395 out:
 396     ccsiv_ctx_clear(mode->size, ctx);
 397
 398     if(error) {
 399         *error = localerror;
 400     }
 401     return localerror == NULL;
 402 }
 403
 404
 405 @end
 406
 407 #endif // OCTAGON