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