1 /* 2 * NIST SP800-38C compliant CCM implementation 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may 8 * not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 /* 21 * Definition of CCM: 22 * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf 23 * RFC 3610 "Counter with CBC-MAC (CCM)" 24 * 25 * Related: 26 * RFC 5116 "An Interface and Algorithms for Authenticated Encryption" 27 */ 28 29 #include "common.h" 30 31 #if defined(MBEDTLS_CCM_C) 32 33 #include "mbedtls/ccm.h" 34 #include "mbedtls/platform_util.h" 35 #include "mbedtls/error.h" 36 37 #include <string.h> 38 39 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 40 #if defined(MBEDTLS_PLATFORM_C) 41 #include "mbedtls/platform.h" 42 #else 43 #include <stdio.h> 44 #define mbedtls_printf printf 45 #endif /* MBEDTLS_PLATFORM_C */ 46 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 47 48 #if !defined(MBEDTLS_CCM_ALT) 49 50 #define CCM_VALIDATE_RET( cond ) \ 51 MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_CCM_BAD_INPUT ) 52 #define CCM_VALIDATE( cond ) \ 53 MBEDTLS_INTERNAL_VALIDATE( cond ) 54 55 #define CCM_ENCRYPT 0 56 #define CCM_DECRYPT 1 57 58 /* 59 * Initialize context 60 */ 61 void mbedtls_ccm_init( mbedtls_ccm_context *ctx ) 62 { 63 CCM_VALIDATE( ctx != NULL ); 64 memset( ctx, 0, sizeof( mbedtls_ccm_context ) ); 65 } 66 67 int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx, 68 mbedtls_cipher_id_t cipher, 69 const unsigned char *key, 70 unsigned int keybits ) 71 { 72 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 73 const mbedtls_cipher_info_t *cipher_info; 74 75 CCM_VALIDATE_RET( ctx != NULL ); 76 CCM_VALIDATE_RET( key != NULL ); 77 78 cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, 79 MBEDTLS_MODE_ECB ); 80 if( cipher_info == NULL ) 81 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 82 83 if( cipher_info->block_size != 16 ) 84 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 85 86 mbedtls_cipher_free( &ctx->cipher_ctx ); 87 88 if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 ) 89 return( ret ); 90 91 if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits, 92 MBEDTLS_ENCRYPT ) ) != 0 ) 93 { 94 return( ret ); 95 } 96 97 return( 0 ); 98 } 99 100 /* 101 * Free context 102 */ 103 void mbedtls_ccm_free( mbedtls_ccm_context *ctx ) 104 { 105 if( ctx == NULL ) 106 return; 107 mbedtls_cipher_free( &ctx->cipher_ctx ); 108 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) ); 109 } 110 111 /* 112 * Macros for common operations. 113 * Results in smaller compiled code than static inline functions. 114 */ 115 116 /* 117 * Update the CBC-MAC state in y using a block in b 118 * (Always using b as the source helps the compiler optimise a bit better.) 119 */ 120 #define UPDATE_CBC_MAC \ 121 for( i = 0; i < 16; i++ ) \ 122 y[i] ^= b[i]; \ 123 \ 124 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \ 125 return( ret ); 126 127 /* 128 * Encrypt or decrypt a partial block with CTR 129 * Warning: using b for temporary storage! src and dst must not be b! 130 * This avoids allocating one more 16 bytes buffer while allowing src == dst. 131 */ 132 #define CTR_CRYPT( dst, src, len ) \ 133 do \ 134 { \ 135 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, \ 136 16, b, &olen ) ) != 0 ) \ 137 { \ 138 return( ret ); \ 139 } \ 140 \ 141 for( i = 0; i < (len); i++ ) \ 142 (dst)[i] = (src)[i] ^ b[i]; \ 143 } while( 0 ) 144 145 /* 146 * Authenticated encryption or decryption 147 */ 148 static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length, 149 const unsigned char *iv, size_t iv_len, 150 const unsigned char *add, size_t add_len, 151 const unsigned char *input, unsigned char *output, 152 unsigned char *tag, size_t tag_len ) 153 { 154 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 155 unsigned char i; 156 unsigned char q; 157 size_t len_left, olen; 158 unsigned char b[16]; 159 unsigned char y[16]; 160 unsigned char ctr[16]; 161 const unsigned char *src; 162 unsigned char *dst; 163 164 /* 165 * Check length requirements: SP800-38C A.1 166 * Additional requirement: a < 2^16 - 2^8 to simplify the code. 167 * 'length' checked later (when writing it to the first block) 168 * 169 * Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4). 170 */ 171 if( tag_len == 2 || tag_len > 16 || tag_len % 2 != 0 ) 172 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 173 174 /* Also implies q is within bounds */ 175 if( iv_len < 7 || iv_len > 13 ) 176 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 177 178 if( add_len >= 0xFF00 ) 179 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 180 181 q = 16 - 1 - (unsigned char) iv_len; 182 183 /* 184 * First block B_0: 185 * 0 .. 0 flags 186 * 1 .. iv_len nonce (aka iv) 187 * iv_len+1 .. 15 length 188 * 189 * With flags as (bits): 190 * 7 0 191 * 6 add present? 192 * 5 .. 3 (t - 2) / 2 193 * 2 .. 0 q - 1 194 */ 195 b[0] = 0; 196 b[0] |= ( add_len > 0 ) << 6; 197 b[0] |= ( ( tag_len - 2 ) / 2 ) << 3; 198 b[0] |= q - 1; 199 200 memcpy( b + 1, iv, iv_len ); 201 202 for( i = 0, len_left = length; i < q; i++, len_left >>= 8 ) 203 b[15-i] = MBEDTLS_BYTE_0( len_left ); 204 205 if( len_left > 0 ) 206 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 207 208 209 /* Start CBC-MAC with first block */ 210 memset( y, 0, 16 ); 211 UPDATE_CBC_MAC; 212 213 /* 214 * If there is additional data, update CBC-MAC with 215 * add_len, add, 0 (padding to a block boundary) 216 */ 217 if( add_len > 0 ) 218 { 219 size_t use_len; 220 len_left = add_len; 221 src = add; 222 223 memset( b, 0, 16 ); 224 MBEDTLS_PUT_UINT16_BE( add_len, b, 0 ); 225 226 use_len = len_left < 16 - 2 ? len_left : 16 - 2; 227 memcpy( b + 2, src, use_len ); 228 len_left -= use_len; 229 src += use_len; 230 231 UPDATE_CBC_MAC; 232 233 while( len_left > 0 ) 234 { 235 use_len = len_left > 16 ? 16 : len_left; 236 237 memset( b, 0, 16 ); 238 memcpy( b, src, use_len ); 239 UPDATE_CBC_MAC; 240 241 len_left -= use_len; 242 src += use_len; 243 } 244 } 245 246 /* 247 * Prepare counter block for encryption: 248 * 0 .. 0 flags 249 * 1 .. iv_len nonce (aka iv) 250 * iv_len+1 .. 15 counter (initially 1) 251 * 252 * With flags as (bits): 253 * 7 .. 3 0 254 * 2 .. 0 q - 1 255 */ 256 ctr[0] = q - 1; 257 memcpy( ctr + 1, iv, iv_len ); 258 memset( ctr + 1 + iv_len, 0, q ); 259 ctr[15] = 1; 260 261 /* 262 * Authenticate and {en,de}crypt the message. 263 * 264 * The only difference between encryption and decryption is 265 * the respective order of authentication and {en,de}cryption. 266 */ 267 len_left = length; 268 src = input; 269 dst = output; 270 271 while( len_left > 0 ) 272 { 273 size_t use_len = len_left > 16 ? 16 : len_left; 274 275 if( mode == CCM_ENCRYPT ) 276 { 277 memset( b, 0, 16 ); 278 memcpy( b, src, use_len ); 279 UPDATE_CBC_MAC; 280 } 281 282 CTR_CRYPT( dst, src, use_len ); 283 284 if( mode == CCM_DECRYPT ) 285 { 286 memset( b, 0, 16 ); 287 memcpy( b, dst, use_len ); 288 UPDATE_CBC_MAC; 289 } 290 291 dst += use_len; 292 src += use_len; 293 len_left -= use_len; 294 295 /* 296 * Increment counter. 297 * No need to check for overflow thanks to the length check above. 298 */ 299 for( i = 0; i < q; i++ ) 300 if( ++ctr[15-i] != 0 ) 301 break; 302 } 303 304 /* 305 * Authentication: reset counter and crypt/mask internal tag 306 */ 307 for( i = 0; i < q; i++ ) 308 ctr[15-i] = 0; 309 310 CTR_CRYPT( y, y, 16 ); 311 memcpy( tag, y, tag_len ); 312 313 return( 0 ); 314 } 315 316 /* 317 * Authenticated encryption 318 */ 319 int mbedtls_ccm_star_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 320 const unsigned char *iv, size_t iv_len, 321 const unsigned char *add, size_t add_len, 322 const unsigned char *input, unsigned char *output, 323 unsigned char *tag, size_t tag_len ) 324 { 325 CCM_VALIDATE_RET( ctx != NULL ); 326 CCM_VALIDATE_RET( iv != NULL ); 327 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 328 CCM_VALIDATE_RET( length == 0 || input != NULL ); 329 CCM_VALIDATE_RET( length == 0 || output != NULL ); 330 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 331 return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len, 332 add, add_len, input, output, tag, tag_len ) ); 333 } 334 335 int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 336 const unsigned char *iv, size_t iv_len, 337 const unsigned char *add, size_t add_len, 338 const unsigned char *input, unsigned char *output, 339 unsigned char *tag, size_t tag_len ) 340 { 341 CCM_VALIDATE_RET( ctx != NULL ); 342 CCM_VALIDATE_RET( iv != NULL ); 343 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 344 CCM_VALIDATE_RET( length == 0 || input != NULL ); 345 CCM_VALIDATE_RET( length == 0 || output != NULL ); 346 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 347 if( tag_len == 0 ) 348 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 349 350 return( mbedtls_ccm_star_encrypt_and_tag( ctx, length, iv, iv_len, add, 351 add_len, input, output, tag, tag_len ) ); 352 } 353 354 /* 355 * Authenticated decryption 356 */ 357 int mbedtls_ccm_star_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 358 const unsigned char *iv, size_t iv_len, 359 const unsigned char *add, size_t add_len, 360 const unsigned char *input, unsigned char *output, 361 const unsigned char *tag, size_t tag_len ) 362 { 363 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 364 unsigned char check_tag[16]; 365 unsigned char i; 366 int diff; 367 368 CCM_VALIDATE_RET( ctx != NULL ); 369 CCM_VALIDATE_RET( iv != NULL ); 370 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 371 CCM_VALIDATE_RET( length == 0 || input != NULL ); 372 CCM_VALIDATE_RET( length == 0 || output != NULL ); 373 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 374 375 if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length, 376 iv, iv_len, add, add_len, 377 input, output, check_tag, tag_len ) ) != 0 ) 378 { 379 return( ret ); 380 } 381 382 /* Check tag in "constant-time" */ 383 for( diff = 0, i = 0; i < tag_len; i++ ) 384 diff |= tag[i] ^ check_tag[i]; 385 386 if( diff != 0 ) 387 { 388 mbedtls_platform_zeroize( output, length ); 389 return( MBEDTLS_ERR_CCM_AUTH_FAILED ); 390 } 391 392 return( 0 ); 393 } 394 395 int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 396 const unsigned char *iv, size_t iv_len, 397 const unsigned char *add, size_t add_len, 398 const unsigned char *input, unsigned char *output, 399 const unsigned char *tag, size_t tag_len ) 400 { 401 CCM_VALIDATE_RET( ctx != NULL ); 402 CCM_VALIDATE_RET( iv != NULL ); 403 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 404 CCM_VALIDATE_RET( length == 0 || input != NULL ); 405 CCM_VALIDATE_RET( length == 0 || output != NULL ); 406 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 407 408 if( tag_len == 0 ) 409 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 410 411 return( mbedtls_ccm_star_auth_decrypt( ctx, length, iv, iv_len, add, 412 add_len, input, output, tag, tag_len ) ); 413 } 414 #endif /* !MBEDTLS_CCM_ALT */ 415 416 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 417 /* 418 * Examples 1 to 3 from SP800-38C Appendix C 419 */ 420 421 #define NB_TESTS 3 422 #define CCM_SELFTEST_PT_MAX_LEN 24 423 #define CCM_SELFTEST_CT_MAX_LEN 32 424 /* 425 * The data is the same for all tests, only the used length changes 426 */ 427 static const unsigned char key_test_data[] = { 428 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 429 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f 430 }; 431 432 static const unsigned char iv_test_data[] = { 433 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 434 0x18, 0x19, 0x1a, 0x1b 435 }; 436 437 static const unsigned char ad_test_data[] = { 438 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 439 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 440 0x10, 0x11, 0x12, 0x13 441 }; 442 443 static const unsigned char msg_test_data[CCM_SELFTEST_PT_MAX_LEN] = { 444 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 445 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 446 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 447 }; 448 449 static const size_t iv_len_test_data [NB_TESTS] = { 7, 8, 12 }; 450 static const size_t add_len_test_data[NB_TESTS] = { 8, 16, 20 }; 451 static const size_t msg_len_test_data[NB_TESTS] = { 4, 16, 24 }; 452 static const size_t tag_len_test_data[NB_TESTS] = { 4, 6, 8 }; 453 454 static const unsigned char res_test_data[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = { 455 { 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d }, 456 { 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62, 457 0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d, 458 0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd }, 459 { 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a, 460 0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b, 461 0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5, 462 0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 } 463 }; 464 465 int mbedtls_ccm_self_test( int verbose ) 466 { 467 mbedtls_ccm_context ctx; 468 /* 469 * Some hardware accelerators require the input and output buffers 470 * would be in RAM, because the flash is not accessible. 471 * Use buffers on the stack to hold the test vectors data. 472 */ 473 unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN]; 474 unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN]; 475 size_t i; 476 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 477 478 mbedtls_ccm_init( &ctx ); 479 480 if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key_test_data, 481 8 * sizeof key_test_data ) != 0 ) 482 { 483 if( verbose != 0 ) 484 mbedtls_printf( " CCM: setup failed" ); 485 486 return( 1 ); 487 } 488 489 for( i = 0; i < NB_TESTS; i++ ) 490 { 491 if( verbose != 0 ) 492 mbedtls_printf( " CCM-AES #%u: ", (unsigned int) i + 1 ); 493 494 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 495 memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN ); 496 memcpy( plaintext, msg_test_data, msg_len_test_data[i] ); 497 498 ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len_test_data[i], 499 iv_test_data, iv_len_test_data[i], 500 ad_test_data, add_len_test_data[i], 501 plaintext, ciphertext, 502 ciphertext + msg_len_test_data[i], 503 tag_len_test_data[i] ); 504 505 if( ret != 0 || 506 memcmp( ciphertext, res_test_data[i], 507 msg_len_test_data[i] + tag_len_test_data[i] ) != 0 ) 508 { 509 if( verbose != 0 ) 510 mbedtls_printf( "failed\n" ); 511 512 return( 1 ); 513 } 514 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 515 516 ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len_test_data[i], 517 iv_test_data, iv_len_test_data[i], 518 ad_test_data, add_len_test_data[i], 519 ciphertext, plaintext, 520 ciphertext + msg_len_test_data[i], 521 tag_len_test_data[i] ); 522 523 if( ret != 0 || 524 memcmp( plaintext, msg_test_data, msg_len_test_data[i] ) != 0 ) 525 { 526 if( verbose != 0 ) 527 mbedtls_printf( "failed\n" ); 528 529 return( 1 ); 530 } 531 532 if( verbose != 0 ) 533 mbedtls_printf( "passed\n" ); 534 } 535 536 mbedtls_ccm_free( &ctx ); 537 538 if( verbose != 0 ) 539 mbedtls_printf( "\n" ); 540 541 return( 0 ); 542 } 543 544 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 545 546 #endif /* MBEDTLS_CCM_C */ 547