1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * NIST SP800-38C compliant CCM implementation 4 * 5 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 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 * This file is part of mbed TLS (https://tls.mbed.org) 20 */ 21 22 /* 23 * Definition of CCM: 24 * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf 25 * RFC 3610 "Counter with CBC-MAC (CCM)" 26 * 27 * Related: 28 * RFC 5116 "An Interface and Algorithms for Authenticated Encryption" 29 */ 30 31 #if !defined(MBEDTLS_CONFIG_FILE) 32 #include "mbedtls/config.h" 33 #else 34 #include MBEDTLS_CONFIG_FILE 35 #endif 36 37 #if defined(MBEDTLS_CCM_C) 38 39 #include "mbedtls/ccm.h" 40 #include "mbedtls/platform_util.h" 41 #include "mbedtls/error.h" 42 43 #include <string.h> 44 45 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 46 #if defined(MBEDTLS_PLATFORM_C) 47 #include "mbedtls/platform.h" 48 #else 49 #include <stdio.h> 50 #define mbedtls_printf printf 51 #endif /* MBEDTLS_PLATFORM_C */ 52 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 53 54 #if !defined(MBEDTLS_CCM_ALT) 55 56 #define CCM_VALIDATE_RET( cond ) \ 57 MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_CCM_BAD_INPUT ) 58 #define CCM_VALIDATE( cond ) \ 59 MBEDTLS_INTERNAL_VALIDATE( cond ) 60 61 #define CCM_ENCRYPT 0 62 #define CCM_DECRYPT 1 63 64 /* 65 * Initialize context 66 */ 67 void mbedtls_ccm_init( mbedtls_ccm_context *ctx ) 68 { 69 CCM_VALIDATE( ctx != NULL ); 70 memset( ctx, 0, sizeof( mbedtls_ccm_context ) ); 71 } 72 73 int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx, 74 mbedtls_cipher_id_t cipher, 75 const unsigned char *key, 76 unsigned int keybits ) 77 { 78 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 79 const mbedtls_cipher_info_t *cipher_info; 80 81 CCM_VALIDATE_RET( ctx != NULL ); 82 CCM_VALIDATE_RET( key != NULL ); 83 84 cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, 85 MBEDTLS_MODE_ECB ); 86 if( cipher_info == NULL ) 87 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 88 89 if( cipher_info->block_size != 16 ) 90 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 91 92 mbedtls_cipher_free( &ctx->cipher_ctx ); 93 94 if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 ) 95 return( ret ); 96 97 if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits, 98 MBEDTLS_ENCRYPT ) ) != 0 ) 99 { 100 return( ret ); 101 } 102 103 return( 0 ); 104 } 105 106 /* 107 * Free context 108 */ 109 void mbedtls_ccm_free( mbedtls_ccm_context *ctx ) 110 { 111 if( ctx == NULL ) 112 return; 113 mbedtls_cipher_free( &ctx->cipher_ctx ); 114 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) ); 115 } 116 117 /* 118 * Macros for common operations. 119 * Results in smaller compiled code than static inline functions. 120 */ 121 122 /* 123 * Update the CBC-MAC state in y using a block in b 124 * (Always using b as the source helps the compiler optimise a bit better.) 125 */ 126 #define UPDATE_CBC_MAC \ 127 for( i = 0; i < 16; i++ ) \ 128 y[i] ^= b[i]; \ 129 \ 130 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \ 131 return( ret ); 132 133 /* 134 * Encrypt or decrypt a partial block with CTR 135 * Warning: using b for temporary storage! src and dst must not be b! 136 * This avoids allocating one more 16 bytes buffer while allowing src == dst. 137 */ 138 #define CTR_CRYPT( dst, src, len ) \ 139 do \ 140 { \ 141 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, \ 142 16, b, &olen ) ) != 0 ) \ 143 { \ 144 return( ret ); \ 145 } \ 146 \ 147 for( i = 0; i < (len); i++ ) \ 148 (dst)[i] = (src)[i] ^ b[i]; \ 149 } while( 0 ) 150 151 /* 152 * Authenticated encryption or decryption 153 */ 154 static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length, 155 const unsigned char *iv, size_t iv_len, 156 const unsigned char *add, size_t add_len, 157 const unsigned char *input, unsigned char *output, 158 unsigned char *tag, size_t tag_len ) 159 { 160 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 161 unsigned char i; 162 unsigned char q; 163 size_t len_left, olen; 164 unsigned char b[16]; 165 unsigned char y[16]; 166 unsigned char ctr[16]; 167 const unsigned char *src; 168 unsigned char *dst; 169 170 /* 171 * Check length requirements: SP800-38C A.1 172 * Additional requirement: a < 2^16 - 2^8 to simplify the code. 173 * 'length' checked later (when writing it to the first block) 174 * 175 * Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4). 176 */ 177 if( tag_len == 2 || tag_len > 16 || tag_len % 2 != 0 ) 178 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 179 180 /* Also implies q is within bounds */ 181 if( iv_len < 7 || iv_len > 13 ) 182 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 183 184 if( add_len > 0xFF00 ) 185 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 186 187 q = 16 - 1 - (unsigned char) iv_len; 188 189 /* 190 * First block B_0: 191 * 0 .. 0 flags 192 * 1 .. iv_len nonce (aka iv) 193 * iv_len+1 .. 15 length 194 * 195 * With flags as (bits): 196 * 7 0 197 * 6 add present? 198 * 5 .. 3 (t - 2) / 2 199 * 2 .. 0 q - 1 200 */ 201 b[0] = 0; 202 b[0] |= ( add_len > 0 ) << 6; 203 b[0] |= ( ( tag_len - 2 ) / 2 ) << 3; 204 b[0] |= q - 1; 205 206 memcpy( b + 1, iv, iv_len ); 207 208 for( i = 0, len_left = length; i < q; i++, len_left >>= 8 ) 209 b[15-i] = (unsigned char)( len_left & 0xFF ); 210 211 if( len_left > 0 ) 212 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 213 214 215 /* Start CBC-MAC with first block */ 216 memset( y, 0, 16 ); 217 UPDATE_CBC_MAC; 218 219 /* 220 * If there is additional data, update CBC-MAC with 221 * add_len, add, 0 (padding to a block boundary) 222 */ 223 if( add_len > 0 ) 224 { 225 size_t use_len; 226 len_left = add_len; 227 src = add; 228 229 memset( b, 0, 16 ); 230 b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF ); 231 b[1] = (unsigned char)( ( add_len ) & 0xFF ); 232 233 use_len = len_left < 16 - 2 ? len_left : 16 - 2; 234 memcpy( b + 2, src, use_len ); 235 len_left -= use_len; 236 src += use_len; 237 238 UPDATE_CBC_MAC; 239 240 while( len_left > 0 ) 241 { 242 use_len = len_left > 16 ? 16 : len_left; 243 244 memset( b, 0, 16 ); 245 memcpy( b, src, use_len ); 246 UPDATE_CBC_MAC; 247 248 len_left -= use_len; 249 src += use_len; 250 } 251 } 252 253 /* 254 * Prepare counter block for encryption: 255 * 0 .. 0 flags 256 * 1 .. iv_len nonce (aka iv) 257 * iv_len+1 .. 15 counter (initially 1) 258 * 259 * With flags as (bits): 260 * 7 .. 3 0 261 * 2 .. 0 q - 1 262 */ 263 ctr[0] = q - 1; 264 memcpy( ctr + 1, iv, iv_len ); 265 memset( ctr + 1 + iv_len, 0, q ); 266 ctr[15] = 1; 267 268 /* 269 * Authenticate and {en,de}crypt the message. 270 * 271 * The only difference between encryption and decryption is 272 * the respective order of authentication and {en,de}cryption. 273 */ 274 len_left = length; 275 src = input; 276 dst = output; 277 278 while( len_left > 0 ) 279 { 280 size_t use_len = len_left > 16 ? 16 : len_left; 281 282 if( mode == CCM_ENCRYPT ) 283 { 284 memset( b, 0, 16 ); 285 memcpy( b, src, use_len ); 286 UPDATE_CBC_MAC; 287 } 288 289 CTR_CRYPT( dst, src, use_len ); 290 291 if( mode == CCM_DECRYPT ) 292 { 293 memset( b, 0, 16 ); 294 memcpy( b, dst, use_len ); 295 UPDATE_CBC_MAC; 296 } 297 298 dst += use_len; 299 src += use_len; 300 len_left -= use_len; 301 302 /* 303 * Increment counter. 304 * No need to check for overflow thanks to the length check above. 305 */ 306 for( i = 0; i < q; i++ ) 307 if( ++ctr[15-i] != 0 ) 308 break; 309 } 310 311 /* 312 * Authentication: reset counter and crypt/mask internal tag 313 */ 314 for( i = 0; i < q; i++ ) 315 ctr[15-i] = 0; 316 317 CTR_CRYPT( y, y, 16 ); 318 memcpy( tag, y, tag_len ); 319 320 return( 0 ); 321 } 322 323 /* 324 * Authenticated encryption 325 */ 326 int mbedtls_ccm_star_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 327 const unsigned char *iv, size_t iv_len, 328 const unsigned char *add, size_t add_len, 329 const unsigned char *input, unsigned char *output, 330 unsigned char *tag, size_t tag_len ) 331 { 332 CCM_VALIDATE_RET( ctx != NULL ); 333 CCM_VALIDATE_RET( iv != NULL ); 334 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 335 CCM_VALIDATE_RET( length == 0 || input != NULL ); 336 CCM_VALIDATE_RET( length == 0 || output != NULL ); 337 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 338 return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len, 339 add, add_len, input, output, tag, tag_len ) ); 340 } 341 342 int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 343 const unsigned char *iv, size_t iv_len, 344 const unsigned char *add, size_t add_len, 345 const unsigned char *input, unsigned char *output, 346 unsigned char *tag, size_t tag_len ) 347 { 348 CCM_VALIDATE_RET( ctx != NULL ); 349 CCM_VALIDATE_RET( iv != NULL ); 350 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 351 CCM_VALIDATE_RET( length == 0 || input != NULL ); 352 CCM_VALIDATE_RET( length == 0 || output != NULL ); 353 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 354 if( tag_len == 0 ) 355 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 356 357 return( mbedtls_ccm_star_encrypt_and_tag( ctx, length, iv, iv_len, add, 358 add_len, input, output, tag, tag_len ) ); 359 } 360 361 /* 362 * Authenticated decryption 363 */ 364 int mbedtls_ccm_star_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 365 const unsigned char *iv, size_t iv_len, 366 const unsigned char *add, size_t add_len, 367 const unsigned char *input, unsigned char *output, 368 const unsigned char *tag, size_t tag_len ) 369 { 370 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 371 unsigned char check_tag[16]; 372 unsigned char i; 373 int diff; 374 375 CCM_VALIDATE_RET( ctx != NULL ); 376 CCM_VALIDATE_RET( iv != NULL ); 377 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 378 CCM_VALIDATE_RET( length == 0 || input != NULL ); 379 CCM_VALIDATE_RET( length == 0 || output != NULL ); 380 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 381 382 if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length, 383 iv, iv_len, add, add_len, 384 input, output, check_tag, tag_len ) ) != 0 ) 385 { 386 return( ret ); 387 } 388 389 /* Check tag in "constant-time" */ 390 for( diff = 0, i = 0; i < tag_len; i++ ) 391 diff |= tag[i] ^ check_tag[i]; 392 393 if( diff != 0 ) 394 { 395 mbedtls_platform_zeroize( output, length ); 396 return( MBEDTLS_ERR_CCM_AUTH_FAILED ); 397 } 398 399 return( 0 ); 400 } 401 402 int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 403 const unsigned char *iv, size_t iv_len, 404 const unsigned char *add, size_t add_len, 405 const unsigned char *input, unsigned char *output, 406 const unsigned char *tag, size_t tag_len ) 407 { 408 CCM_VALIDATE_RET( ctx != NULL ); 409 CCM_VALIDATE_RET( iv != NULL ); 410 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 411 CCM_VALIDATE_RET( length == 0 || input != NULL ); 412 CCM_VALIDATE_RET( length == 0 || output != NULL ); 413 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 414 415 if( tag_len == 0 ) 416 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 417 418 return( mbedtls_ccm_star_auth_decrypt( ctx, length, iv, iv_len, add, 419 add_len, input, output, tag, tag_len ) ); 420 } 421 #endif /* !MBEDTLS_CCM_ALT */ 422 423 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 424 /* 425 * Examples 1 to 3 from SP800-38C Appendix C 426 */ 427 428 #define NB_TESTS 3 429 #define CCM_SELFTEST_PT_MAX_LEN 24 430 #define CCM_SELFTEST_CT_MAX_LEN 32 431 /* 432 * The data is the same for all tests, only the used length changes 433 */ 434 static const unsigned char key_test_data[] = { 435 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 436 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f 437 }; 438 439 static const unsigned char iv_test_data[] = { 440 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 441 0x18, 0x19, 0x1a, 0x1b 442 }; 443 444 static const unsigned char ad_test_data[] = { 445 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 446 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 447 0x10, 0x11, 0x12, 0x13 448 }; 449 450 static const unsigned char msg_test_data[CCM_SELFTEST_PT_MAX_LEN] = { 451 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 452 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 453 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 454 }; 455 456 static const size_t iv_len_test_data [NB_TESTS] = { 7, 8, 12 }; 457 static const size_t add_len_test_data[NB_TESTS] = { 8, 16, 20 }; 458 static const size_t msg_len_test_data[NB_TESTS] = { 4, 16, 24 }; 459 static const size_t tag_len_test_data[NB_TESTS] = { 4, 6, 8 }; 460 461 static const unsigned char res_test_data[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = { 462 { 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d }, 463 { 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62, 464 0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d, 465 0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd }, 466 { 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a, 467 0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b, 468 0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5, 469 0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 } 470 }; 471 472 int mbedtls_ccm_self_test( int verbose ) 473 { 474 mbedtls_ccm_context ctx; 475 /* 476 * Some hardware accelerators require the input and output buffers 477 * would be in RAM, because the flash is not accessible. 478 * Use buffers on the stack to hold the test vectors data. 479 */ 480 unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN]; 481 unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN]; 482 size_t i; 483 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 484 485 mbedtls_ccm_init( &ctx ); 486 487 if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key_test_data, 488 8 * sizeof key_test_data ) != 0 ) 489 { 490 if( verbose != 0 ) 491 mbedtls_printf( " CCM: setup failed" ); 492 493 return( 1 ); 494 } 495 496 for( i = 0; i < NB_TESTS; i++ ) 497 { 498 if( verbose != 0 ) 499 mbedtls_printf( " CCM-AES #%u: ", (unsigned int) i + 1 ); 500 501 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 502 memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN ); 503 memcpy( plaintext, msg_test_data, msg_len_test_data[i] ); 504 505 ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len_test_data[i], 506 iv_test_data, iv_len_test_data[i], 507 ad_test_data, add_len_test_data[i], 508 plaintext, ciphertext, 509 ciphertext + msg_len_test_data[i], 510 tag_len_test_data[i] ); 511 512 if( ret != 0 || 513 memcmp( ciphertext, res_test_data[i], 514 msg_len_test_data[i] + tag_len_test_data[i] ) != 0 ) 515 { 516 if( verbose != 0 ) 517 mbedtls_printf( "failed\n" ); 518 519 return( 1 ); 520 } 521 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 522 523 ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len_test_data[i], 524 iv_test_data, iv_len_test_data[i], 525 ad_test_data, add_len_test_data[i], 526 ciphertext, plaintext, 527 ciphertext + msg_len_test_data[i], 528 tag_len_test_data[i] ); 529 530 if( ret != 0 || 531 memcmp( plaintext, msg_test_data, msg_len_test_data[i] ) != 0 ) 532 { 533 if( verbose != 0 ) 534 mbedtls_printf( "failed\n" ); 535 536 return( 1 ); 537 } 538 539 if( verbose != 0 ) 540 mbedtls_printf( "passed\n" ); 541 } 542 543 mbedtls_ccm_free( &ctx ); 544 545 if( verbose != 0 ) 546 mbedtls_printf( "\n" ); 547 548 return( 0 ); 549 } 550 551 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 552 553 #endif /* MBEDTLS_CCM_C */ 554