1 /* 2 * NIST SP800-38C compliant CCM implementation 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 */ 46 47 /* 48 * Definition of CCM: 49 * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf 50 * RFC 3610 "Counter with CBC-MAC (CCM)" 51 * 52 * Related: 53 * RFC 5116 "An Interface and Algorithms for Authenticated Encryption" 54 */ 55 56 #if !defined(MBEDTLS_CONFIG_FILE) 57 #include "mbedtls/config.h" 58 #else 59 #include MBEDTLS_CONFIG_FILE 60 #endif 61 62 #if defined(MBEDTLS_CCM_C) 63 64 #include "mbedtls/ccm.h" 65 #include "mbedtls/platform_util.h" 66 67 #include <string.h> 68 69 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 70 #if defined(MBEDTLS_PLATFORM_C) 71 #include "mbedtls/platform.h" 72 #else 73 #include <stdio.h> 74 #define mbedtls_printf printf 75 #endif /* MBEDTLS_PLATFORM_C */ 76 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 77 78 #if !defined(MBEDTLS_CCM_ALT) 79 80 #define CCM_VALIDATE_RET( cond ) \ 81 MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_CCM_BAD_INPUT ) 82 #define CCM_VALIDATE( cond ) \ 83 MBEDTLS_INTERNAL_VALIDATE( cond ) 84 85 #define CCM_ENCRYPT 0 86 #define CCM_DECRYPT 1 87 88 /* 89 * Initialize context 90 */ 91 void mbedtls_ccm_init( mbedtls_ccm_context *ctx ) 92 { 93 CCM_VALIDATE( ctx != NULL ); 94 memset( ctx, 0, sizeof( mbedtls_ccm_context ) ); 95 } 96 97 int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx, 98 mbedtls_cipher_id_t cipher, 99 const unsigned char *key, 100 unsigned int keybits ) 101 { 102 int ret; 103 const mbedtls_cipher_info_t *cipher_info; 104 105 CCM_VALIDATE_RET( ctx != NULL ); 106 CCM_VALIDATE_RET( key != NULL ); 107 108 cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB ); 109 if( cipher_info == NULL ) 110 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 111 112 if( cipher_info->block_size != 16 ) 113 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 114 115 mbedtls_cipher_free( &ctx->cipher_ctx ); 116 117 if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 ) 118 return( ret ); 119 120 if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits, 121 MBEDTLS_ENCRYPT ) ) != 0 ) 122 { 123 return( ret ); 124 } 125 126 return( 0 ); 127 } 128 129 /* 130 * Free context 131 */ 132 void mbedtls_ccm_free( mbedtls_ccm_context *ctx ) 133 { 134 if( ctx == NULL ) 135 return; 136 mbedtls_cipher_free( &ctx->cipher_ctx ); 137 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) ); 138 } 139 140 /* 141 * Macros for common operations. 142 * Results in smaller compiled code than static inline functions. 143 */ 144 145 /* 146 * Update the CBC-MAC state in y using a block in b 147 * (Always using b as the source helps the compiler optimise a bit better.) 148 */ 149 #define UPDATE_CBC_MAC \ 150 for( i = 0; i < 16; i++ ) \ 151 y[i] ^= b[i]; \ 152 \ 153 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \ 154 return( ret ); 155 156 /* 157 * Encrypt or decrypt a partial block with CTR 158 * Warning: using b for temporary storage! src and dst must not be b! 159 * This avoids allocating one more 16 bytes buffer while allowing src == dst. 160 */ 161 #define CTR_CRYPT( dst, src, len ) \ 162 do \ 163 { \ 164 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, \ 165 16, b, &olen ) ) != 0 ) \ 166 { \ 167 return( ret ); \ 168 } \ 169 \ 170 for( i = 0; i < (len); i++ ) \ 171 (dst)[i] = (src)[i] ^ b[i]; \ 172 } while( 0 ) 173 174 /* 175 * Authenticated encryption or decryption 176 */ 177 static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length, 178 const unsigned char *iv, size_t iv_len, 179 const unsigned char *add, size_t add_len, 180 const unsigned char *input, unsigned char *output, 181 unsigned char *tag, size_t tag_len ) 182 { 183 int ret; 184 unsigned char i; 185 unsigned char q; 186 size_t len_left, olen; 187 unsigned char b[16]; 188 unsigned char y[16]; 189 unsigned char ctr[16]; 190 const unsigned char *src; 191 unsigned char *dst; 192 193 /* 194 * Check length requirements: SP800-38C A.1 195 * Additional requirement: a < 2^16 - 2^8 to simplify the code. 196 * 'length' checked later (when writing it to the first block) 197 * 198 * Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4). 199 */ 200 if( tag_len == 2 || tag_len > 16 || tag_len % 2 != 0 ) 201 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 202 203 /* Also implies q is within bounds */ 204 if( iv_len < 7 || iv_len > 13 ) 205 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 206 207 if( add_len > 0xFF00 ) 208 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 209 210 q = 16 - 1 - (unsigned char) iv_len; 211 212 /* 213 * First block B_0: 214 * 0 .. 0 flags 215 * 1 .. iv_len nonce (aka iv) 216 * iv_len+1 .. 15 length 217 * 218 * With flags as (bits): 219 * 7 0 220 * 6 add present? 221 * 5 .. 3 (t - 2) / 2 222 * 2 .. 0 q - 1 223 */ 224 b[0] = 0; 225 b[0] |= ( add_len > 0 ) << 6; 226 b[0] |= ( ( tag_len - 2 ) / 2 ) << 3; 227 b[0] |= q - 1; 228 229 memcpy( b + 1, iv, iv_len ); 230 231 for( i = 0, len_left = length; i < q; i++, len_left >>= 8 ) 232 b[15-i] = (unsigned char)( len_left & 0xFF ); 233 234 if( len_left > 0 ) 235 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 236 237 238 /* Start CBC-MAC with first block */ 239 memset( y, 0, 16 ); 240 UPDATE_CBC_MAC; 241 242 /* 243 * If there is additional data, update CBC-MAC with 244 * add_len, add, 0 (padding to a block boundary) 245 */ 246 if( add_len > 0 ) 247 { 248 size_t use_len; 249 len_left = add_len; 250 src = add; 251 252 memset( b, 0, 16 ); 253 b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF ); 254 b[1] = (unsigned char)( ( add_len ) & 0xFF ); 255 256 use_len = len_left < 16 - 2 ? len_left : 16 - 2; 257 memcpy( b + 2, src, use_len ); 258 len_left -= use_len; 259 src += use_len; 260 261 UPDATE_CBC_MAC; 262 263 while( len_left > 0 ) 264 { 265 use_len = len_left > 16 ? 16 : len_left; 266 267 memset( b, 0, 16 ); 268 memcpy( b, src, use_len ); 269 UPDATE_CBC_MAC; 270 271 len_left -= use_len; 272 src += use_len; 273 } 274 } 275 276 /* 277 * Prepare counter block for encryption: 278 * 0 .. 0 flags 279 * 1 .. iv_len nonce (aka iv) 280 * iv_len+1 .. 15 counter (initially 1) 281 * 282 * With flags as (bits): 283 * 7 .. 3 0 284 * 2 .. 0 q - 1 285 */ 286 ctr[0] = q - 1; 287 memcpy( ctr + 1, iv, iv_len ); 288 memset( ctr + 1 + iv_len, 0, q ); 289 ctr[15] = 1; 290 291 /* 292 * Authenticate and {en,de}crypt the message. 293 * 294 * The only difference between encryption and decryption is 295 * the respective order of authentication and {en,de}cryption. 296 */ 297 len_left = length; 298 src = input; 299 dst = output; 300 301 while( len_left > 0 ) 302 { 303 size_t use_len = len_left > 16 ? 16 : len_left; 304 305 if( mode == CCM_ENCRYPT ) 306 { 307 memset( b, 0, 16 ); 308 memcpy( b, src, use_len ); 309 UPDATE_CBC_MAC; 310 } 311 312 CTR_CRYPT( dst, src, use_len ); 313 314 if( mode == CCM_DECRYPT ) 315 { 316 memset( b, 0, 16 ); 317 memcpy( b, dst, use_len ); 318 UPDATE_CBC_MAC; 319 } 320 321 dst += use_len; 322 src += use_len; 323 len_left -= use_len; 324 325 /* 326 * Increment counter. 327 * No need to check for overflow thanks to the length check above. 328 */ 329 for( i = 0; i < q; i++ ) 330 if( ++ctr[15-i] != 0 ) 331 break; 332 } 333 334 /* 335 * Authentication: reset counter and crypt/mask internal tag 336 */ 337 for( i = 0; i < q; i++ ) 338 ctr[15-i] = 0; 339 340 CTR_CRYPT( y, y, 16 ); 341 memcpy( tag, y, tag_len ); 342 343 return( 0 ); 344 } 345 346 /* 347 * Authenticated encryption 348 */ 349 int mbedtls_ccm_star_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 350 const unsigned char *iv, size_t iv_len, 351 const unsigned char *add, size_t add_len, 352 const unsigned char *input, unsigned char *output, 353 unsigned char *tag, size_t tag_len ) 354 { 355 CCM_VALIDATE_RET( ctx != NULL ); 356 CCM_VALIDATE_RET( iv != NULL ); 357 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 358 CCM_VALIDATE_RET( length == 0 || input != NULL ); 359 CCM_VALIDATE_RET( length == 0 || output != NULL ); 360 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 361 return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len, 362 add, add_len, input, output, tag, tag_len ) ); 363 } 364 365 int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 366 const unsigned char *iv, size_t iv_len, 367 const unsigned char *add, size_t add_len, 368 const unsigned char *input, unsigned char *output, 369 unsigned char *tag, size_t tag_len ) 370 { 371 CCM_VALIDATE_RET( ctx != NULL ); 372 CCM_VALIDATE_RET( iv != NULL ); 373 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 374 CCM_VALIDATE_RET( length == 0 || input != NULL ); 375 CCM_VALIDATE_RET( length == 0 || output != NULL ); 376 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 377 if( tag_len == 0 ) 378 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 379 380 return( mbedtls_ccm_star_encrypt_and_tag( ctx, length, iv, iv_len, add, 381 add_len, input, output, tag, tag_len ) ); 382 } 383 384 /* 385 * Authenticated decryption 386 */ 387 int mbedtls_ccm_star_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 388 const unsigned char *iv, size_t iv_len, 389 const unsigned char *add, size_t add_len, 390 const unsigned char *input, unsigned char *output, 391 const unsigned char *tag, size_t tag_len ) 392 { 393 int ret; 394 unsigned char check_tag[16]; 395 unsigned char i; 396 int diff; 397 398 CCM_VALIDATE_RET( ctx != NULL ); 399 CCM_VALIDATE_RET( iv != NULL ); 400 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 401 CCM_VALIDATE_RET( length == 0 || input != NULL ); 402 CCM_VALIDATE_RET( length == 0 || output != NULL ); 403 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 404 405 if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length, 406 iv, iv_len, add, add_len, 407 input, output, check_tag, tag_len ) ) != 0 ) 408 { 409 return( ret ); 410 } 411 412 /* Check tag in "constant-time" */ 413 for( diff = 0, i = 0; i < tag_len; i++ ) 414 diff |= tag[i] ^ check_tag[i]; 415 416 if( diff != 0 ) 417 { 418 mbedtls_platform_zeroize( output, length ); 419 return( MBEDTLS_ERR_CCM_AUTH_FAILED ); 420 } 421 422 return( 0 ); 423 } 424 425 int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 426 const unsigned char *iv, size_t iv_len, 427 const unsigned char *add, size_t add_len, 428 const unsigned char *input, unsigned char *output, 429 const unsigned char *tag, size_t tag_len ) 430 { 431 CCM_VALIDATE_RET( ctx != NULL ); 432 CCM_VALIDATE_RET( iv != NULL ); 433 CCM_VALIDATE_RET( add_len == 0 || add != NULL ); 434 CCM_VALIDATE_RET( length == 0 || input != NULL ); 435 CCM_VALIDATE_RET( length == 0 || output != NULL ); 436 CCM_VALIDATE_RET( tag_len == 0 || tag != NULL ); 437 438 if( tag_len == 0 ) 439 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 440 441 return( mbedtls_ccm_star_auth_decrypt( ctx, length, iv, iv_len, add, 442 add_len, input, output, tag, tag_len ) ); 443 } 444 #endif /* !MBEDTLS_CCM_ALT */ 445 446 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 447 /* 448 * Examples 1 to 3 from SP800-38C Appendix C 449 */ 450 451 #define NB_TESTS 3 452 #define CCM_SELFTEST_PT_MAX_LEN 24 453 #define CCM_SELFTEST_CT_MAX_LEN 32 454 /* 455 * The data is the same for all tests, only the used length changes 456 */ 457 static const unsigned char key[] = { 458 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 459 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f 460 }; 461 462 static const unsigned char iv[] = { 463 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 464 0x18, 0x19, 0x1a, 0x1b 465 }; 466 467 static const unsigned char ad[] = { 468 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 469 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 470 0x10, 0x11, 0x12, 0x13 471 }; 472 473 static const unsigned char msg[CCM_SELFTEST_PT_MAX_LEN] = { 474 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 475 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 476 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 477 }; 478 479 static const size_t iv_len [NB_TESTS] = { 7, 8, 12 }; 480 static const size_t add_len[NB_TESTS] = { 8, 16, 20 }; 481 static const size_t msg_len[NB_TESTS] = { 4, 16, 24 }; 482 static const size_t tag_len[NB_TESTS] = { 4, 6, 8 }; 483 484 static const unsigned char res[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = { 485 { 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d }, 486 { 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62, 487 0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d, 488 0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd }, 489 { 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a, 490 0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b, 491 0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5, 492 0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 } 493 }; 494 495 int mbedtls_ccm_self_test( int verbose ) 496 { 497 mbedtls_ccm_context ctx; 498 /* 499 * Some hardware accelerators require the input and output buffers 500 * would be in RAM, because the flash is not accessible. 501 * Use buffers on the stack to hold the test vectors data. 502 */ 503 unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN]; 504 unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN]; 505 size_t i; 506 int ret; 507 508 mbedtls_ccm_init( &ctx ); 509 510 if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 ) 511 { 512 if( verbose != 0 ) 513 mbedtls_printf( " CCM: setup failed" ); 514 515 return( 1 ); 516 } 517 518 for( i = 0; i < NB_TESTS; i++ ) 519 { 520 if( verbose != 0 ) 521 mbedtls_printf( " CCM-AES #%u: ", (unsigned int) i + 1 ); 522 523 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 524 memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN ); 525 memcpy( plaintext, msg, msg_len[i] ); 526 527 ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i], 528 iv, iv_len[i], ad, add_len[i], 529 plaintext, ciphertext, 530 ciphertext + msg_len[i], tag_len[i] ); 531 532 if( ret != 0 || 533 memcmp( ciphertext, res[i], msg_len[i] + tag_len[i] ) != 0 ) 534 { 535 if( verbose != 0 ) 536 mbedtls_printf( "failed\n" ); 537 538 return( 1 ); 539 } 540 memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN ); 541 542 ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i], 543 iv, iv_len[i], ad, add_len[i], 544 ciphertext, plaintext, 545 ciphertext + msg_len[i], tag_len[i] ); 546 547 if( ret != 0 || 548 memcmp( plaintext, msg, msg_len[i] ) != 0 ) 549 { 550 if( verbose != 0 ) 551 mbedtls_printf( "failed\n" ); 552 553 return( 1 ); 554 } 555 556 if( verbose != 0 ) 557 mbedtls_printf( "passed\n" ); 558 } 559 560 mbedtls_ccm_free( &ctx ); 561 562 if( verbose != 0 ) 563 mbedtls_printf( "\n" ); 564 565 return( 0 ); 566 } 567 568 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 569 570 #endif /* MBEDTLS_CCM_C */ 571