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