Tristan Matthews | 0a329cc | 2013-07-17 13:20:14 -0400 | [diff] [blame] | 1 | /* |
| 2 | * aes_cbc.c |
| 3 | * |
| 4 | * AES Cipher Block Chaining Mode |
| 5 | * |
| 6 | * David A. McGrew |
| 7 | * Cisco Systems, Inc. |
| 8 | */ |
| 9 | |
| 10 | /* |
| 11 | * |
| 12 | * Copyright (c) 2001-2006, Cisco Systems, Inc. |
| 13 | * All rights reserved. |
| 14 | * |
| 15 | * Redistribution and use in source and binary forms, with or without |
| 16 | * modification, are permitted provided that the following conditions |
| 17 | * are met: |
| 18 | * |
| 19 | * Redistributions of source code must retain the above copyright |
| 20 | * notice, this list of conditions and the following disclaimer. |
| 21 | * |
| 22 | * Redistributions in binary form must reproduce the above |
| 23 | * copyright notice, this list of conditions and the following |
| 24 | * disclaimer in the documentation and/or other materials provided |
| 25 | * with the distribution. |
| 26 | * |
| 27 | * Neither the name of the Cisco Systems, Inc. nor the names of its |
| 28 | * contributors may be used to endorse or promote products derived |
| 29 | * from this software without specific prior written permission. |
| 30 | * |
| 31 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 32 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 33 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 34 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 35 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
| 36 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| 37 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| 38 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 39 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 40 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 41 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 42 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 43 | * |
| 44 | */ |
| 45 | |
| 46 | |
| 47 | #include "aes_cbc.h" |
| 48 | #include "alloc.h" |
| 49 | |
| 50 | debug_module_t mod_aes_cbc = { |
| 51 | 0, /* debugging is off by default */ |
| 52 | "aes cbc" /* printable module name */ |
| 53 | }; |
| 54 | |
| 55 | |
| 56 | |
| 57 | err_status_t |
| 58 | aes_cbc_alloc(cipher_t **c, int key_len) { |
| 59 | extern cipher_type_t aes_cbc; |
| 60 | uint8_t *pointer; |
| 61 | int tmp; |
| 62 | |
| 63 | debug_print(mod_aes_cbc, |
| 64 | "allocating cipher with key length %d", key_len); |
| 65 | |
| 66 | if (key_len != 16) |
| 67 | return err_status_bad_param; |
| 68 | |
| 69 | /* allocate memory a cipher of type aes_icm */ |
| 70 | tmp = (sizeof(aes_cbc_ctx_t) + sizeof(cipher_t)); |
| 71 | pointer = (uint8_t*)crypto_alloc(tmp); |
| 72 | if (pointer == NULL) |
| 73 | return err_status_alloc_fail; |
| 74 | |
| 75 | /* set pointers */ |
| 76 | *c = (cipher_t *)pointer; |
| 77 | (*c)->type = &aes_cbc; |
| 78 | (*c)->state = pointer + sizeof(cipher_t); |
| 79 | |
| 80 | /* increment ref_count */ |
| 81 | aes_cbc.ref_count++; |
| 82 | |
| 83 | /* set key size */ |
| 84 | (*c)->key_len = key_len; |
| 85 | |
| 86 | return err_status_ok; |
| 87 | } |
| 88 | |
| 89 | err_status_t |
| 90 | aes_cbc_dealloc(cipher_t *c) { |
| 91 | extern cipher_type_t aes_cbc; |
| 92 | |
| 93 | /* zeroize entire state*/ |
| 94 | octet_string_set_to_zero((uint8_t *)c, |
| 95 | sizeof(aes_cbc_ctx_t) + sizeof(cipher_t)); |
| 96 | |
| 97 | /* free memory */ |
| 98 | crypto_free(c); |
| 99 | |
| 100 | /* decrement ref_count */ |
| 101 | aes_cbc.ref_count--; |
| 102 | |
| 103 | return err_status_ok; |
| 104 | } |
| 105 | |
| 106 | err_status_t |
| 107 | aes_cbc_context_init(aes_cbc_ctx_t *c, const uint8_t *key, |
| 108 | cipher_direction_t dir) { |
| 109 | v128_t tmp_key; |
| 110 | |
| 111 | /* set tmp_key (for alignment) */ |
| 112 | v128_copy_octet_string(&tmp_key, key); |
| 113 | |
| 114 | debug_print(mod_aes_cbc, |
| 115 | "key: %s", v128_hex_string(&tmp_key)); |
| 116 | |
| 117 | /* expand key for the appropriate direction */ |
| 118 | switch (dir) { |
| 119 | case (direction_encrypt): |
| 120 | aes_expand_encryption_key(&tmp_key, c->expanded_key); |
| 121 | break; |
| 122 | case (direction_decrypt): |
| 123 | aes_expand_decryption_key(&tmp_key, c->expanded_key); |
| 124 | break; |
| 125 | default: |
| 126 | return err_status_bad_param; |
| 127 | } |
| 128 | |
| 129 | |
| 130 | return err_status_ok; |
| 131 | } |
| 132 | |
| 133 | |
| 134 | err_status_t |
| 135 | aes_cbc_set_iv(aes_cbc_ctx_t *c, void *iv) { |
| 136 | int i; |
| 137 | /* v128_t *input = iv; */ |
| 138 | uint8_t *input = (uint8_t*) iv; |
| 139 | |
| 140 | /* set state and 'previous' block to iv */ |
| 141 | for (i=0; i < 16; i++) |
| 142 | c->previous.v8[i] = c->state.v8[i] = input[i]; |
| 143 | |
| 144 | debug_print(mod_aes_cbc, "setting iv: %s", v128_hex_string(&c->state)); |
| 145 | |
| 146 | return err_status_ok; |
| 147 | } |
| 148 | |
| 149 | err_status_t |
| 150 | aes_cbc_encrypt(aes_cbc_ctx_t *c, |
| 151 | unsigned char *data, |
| 152 | unsigned int *bytes_in_data) { |
| 153 | int i; |
| 154 | unsigned char *input = data; /* pointer to data being read */ |
| 155 | unsigned char *output = data; /* pointer to data being written */ |
| 156 | int bytes_to_encr = *bytes_in_data; |
| 157 | |
| 158 | /* |
| 159 | * verify that we're 16-octet aligned |
| 160 | */ |
| 161 | if (*bytes_in_data & 0xf) |
| 162 | return err_status_bad_param; |
| 163 | |
| 164 | /* |
| 165 | * note that we assume that the initialization vector has already |
| 166 | * been set, e.g. by calling aes_cbc_set_iv() |
| 167 | */ |
| 168 | debug_print(mod_aes_cbc, "iv: %s", |
| 169 | v128_hex_string(&c->state)); |
| 170 | |
| 171 | /* |
| 172 | * loop over plaintext blocks, exoring state into plaintext then |
| 173 | * encrypting and writing to output |
| 174 | */ |
| 175 | while (bytes_to_encr > 0) { |
| 176 | |
| 177 | /* exor plaintext into state */ |
| 178 | for (i=0; i < 16; i++) |
| 179 | c->state.v8[i] ^= *input++; |
| 180 | |
| 181 | debug_print(mod_aes_cbc, "inblock: %s", |
| 182 | v128_hex_string(&c->state)); |
| 183 | |
| 184 | aes_encrypt(&c->state, c->expanded_key); |
| 185 | |
| 186 | debug_print(mod_aes_cbc, "outblock: %s", |
| 187 | v128_hex_string(&c->state)); |
| 188 | |
| 189 | /* copy ciphertext to output */ |
| 190 | for (i=0; i < 16; i++) |
| 191 | *output++ = c->state.v8[i]; |
| 192 | |
| 193 | bytes_to_encr -= 16; |
| 194 | } |
| 195 | |
| 196 | return err_status_ok; |
| 197 | } |
| 198 | |
| 199 | err_status_t |
| 200 | aes_cbc_decrypt(aes_cbc_ctx_t *c, |
| 201 | unsigned char *data, |
| 202 | unsigned int *bytes_in_data) { |
| 203 | int i; |
| 204 | v128_t state, previous; |
| 205 | unsigned char *input = data; /* pointer to data being read */ |
| 206 | unsigned char *output = data; /* pointer to data being written */ |
| 207 | int bytes_to_encr = *bytes_in_data; |
| 208 | uint8_t tmp; |
| 209 | |
| 210 | /* |
| 211 | * verify that we're 16-octet aligned |
| 212 | */ |
| 213 | if (*bytes_in_data & 0x0f) |
| 214 | return err_status_bad_param; |
| 215 | |
| 216 | /* set 'previous' block to iv*/ |
| 217 | for (i=0; i < 16; i++) { |
| 218 | previous.v8[i] = c->previous.v8[i]; |
| 219 | } |
| 220 | |
| 221 | debug_print(mod_aes_cbc, "iv: %s", |
| 222 | v128_hex_string(&previous)); |
| 223 | |
| 224 | /* |
| 225 | * loop over ciphertext blocks, decrypting then exoring with state |
| 226 | * then writing plaintext to output |
| 227 | */ |
| 228 | while (bytes_to_encr > 0) { |
| 229 | |
| 230 | /* set state to ciphertext input block */ |
| 231 | for (i=0; i < 16; i++) { |
| 232 | state.v8[i] = *input++; |
| 233 | } |
| 234 | |
| 235 | debug_print(mod_aes_cbc, "inblock: %s", |
| 236 | v128_hex_string(&state)); |
| 237 | |
| 238 | /* decrypt state */ |
| 239 | aes_decrypt(&state, c->expanded_key); |
| 240 | |
| 241 | debug_print(mod_aes_cbc, "outblock: %s", |
| 242 | v128_hex_string(&state)); |
| 243 | |
| 244 | /* |
| 245 | * exor previous ciphertext block out of plaintext, and write new |
| 246 | * plaintext block to output, while copying old ciphertext block |
| 247 | * to the 'previous' block |
| 248 | */ |
| 249 | for (i=0; i < 16; i++) { |
| 250 | tmp = *output; |
| 251 | *output++ = state.v8[i] ^ previous.v8[i]; |
| 252 | previous.v8[i] = tmp; |
| 253 | } |
| 254 | |
| 255 | bytes_to_encr -= 16; |
| 256 | } |
| 257 | |
| 258 | return err_status_ok; |
| 259 | } |
| 260 | |
| 261 | |
| 262 | err_status_t |
| 263 | aes_cbc_nist_encrypt(aes_cbc_ctx_t *c, |
| 264 | unsigned char *data, |
| 265 | unsigned int *bytes_in_data) { |
| 266 | int i; |
| 267 | unsigned char *pad_start; |
| 268 | int num_pad_bytes; |
| 269 | err_status_t status; |
| 270 | |
| 271 | /* |
| 272 | * determine the number of padding bytes that we need to add - |
| 273 | * this value is always between 1 and 16, inclusive. |
| 274 | */ |
| 275 | num_pad_bytes = 16 - (*bytes_in_data & 0xf); |
| 276 | pad_start = data; |
| 277 | pad_start += *bytes_in_data; |
| 278 | *pad_start++ = 0xa0; |
| 279 | for (i=0; i < num_pad_bytes; i++) |
| 280 | *pad_start++ = 0x00; |
| 281 | |
| 282 | /* |
| 283 | * increment the data size |
| 284 | */ |
| 285 | *bytes_in_data += num_pad_bytes; |
| 286 | |
| 287 | /* |
| 288 | * now cbc encrypt the padded data |
| 289 | */ |
| 290 | status = aes_cbc_encrypt(c, data, bytes_in_data); |
| 291 | if (status) |
| 292 | return status; |
| 293 | |
| 294 | return err_status_ok; |
| 295 | } |
| 296 | |
| 297 | |
| 298 | err_status_t |
| 299 | aes_cbc_nist_decrypt(aes_cbc_ctx_t *c, |
| 300 | unsigned char *data, |
| 301 | unsigned int *bytes_in_data) { |
| 302 | unsigned char *pad_end; |
| 303 | int num_pad_bytes; |
| 304 | err_status_t status; |
| 305 | |
| 306 | /* |
| 307 | * cbc decrypt the padded data |
| 308 | */ |
| 309 | status = aes_cbc_decrypt(c, data, bytes_in_data); |
| 310 | if (status) |
| 311 | return status; |
| 312 | |
| 313 | /* |
| 314 | * determine the number of padding bytes in the decrypted plaintext |
| 315 | * - this value is always between 1 and 16, inclusive. |
| 316 | */ |
| 317 | num_pad_bytes = 1; |
| 318 | pad_end = data + (*bytes_in_data - 1); |
| 319 | while (*pad_end != 0xa0) { /* note: should check padding correctness */ |
| 320 | pad_end--; |
| 321 | num_pad_bytes++; |
| 322 | } |
| 323 | |
| 324 | /* decrement data size */ |
| 325 | *bytes_in_data -= num_pad_bytes; |
| 326 | |
| 327 | return err_status_ok; |
| 328 | } |
| 329 | |
| 330 | |
| 331 | char |
| 332 | aes_cbc_description[] = "aes cipher block chaining (cbc) mode"; |
| 333 | |
| 334 | /* |
| 335 | * Test case 0 is derived from FIPS 197 Appendix A; it uses an |
| 336 | * all-zero IV, so that the first block encryption matches the test |
| 337 | * case in that appendix. This property provides a check of the base |
| 338 | * AES encryption and decryption algorithms; if CBC fails on some |
| 339 | * particular platform, then you should print out AES intermediate |
| 340 | * data and compare with the detailed info provided in that appendix. |
| 341 | * |
| 342 | */ |
| 343 | |
| 344 | |
| 345 | uint8_t aes_cbc_test_case_0_key[16] = { |
| 346 | 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, |
| 347 | 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f |
| 348 | }; |
| 349 | |
| 350 | uint8_t aes_cbc_test_case_0_plaintext[64] = { |
| 351 | 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, |
| 352 | 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff |
| 353 | }; |
| 354 | |
| 355 | uint8_t aes_cbc_test_case_0_ciphertext[80] = { |
| 356 | 0x69, 0xc4, 0xe0, 0xd8, 0x6a, 0x7b, 0x04, 0x30, |
| 357 | 0xd8, 0xcd, 0xb7, 0x80, 0x70, 0xb4, 0xc5, 0x5a, |
| 358 | 0x03, 0x35, 0xed, 0x27, 0x67, 0xf2, 0x6d, 0xf1, |
| 359 | 0x64, 0x83, 0x2e, 0x23, 0x44, 0x38, 0x70, 0x8b |
| 360 | |
| 361 | }; |
| 362 | |
| 363 | uint8_t aes_cbc_test_case_0_iv[16] = { |
| 364 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
| 365 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 |
| 366 | }; |
| 367 | |
| 368 | |
| 369 | cipher_test_case_t aes_cbc_test_case_0 = { |
| 370 | 16, /* octets in key */ |
| 371 | aes_cbc_test_case_0_key, /* key */ |
| 372 | aes_cbc_test_case_0_iv, /* initialization vector */ |
| 373 | 16, /* octets in plaintext */ |
| 374 | aes_cbc_test_case_0_plaintext, /* plaintext */ |
| 375 | 32, /* octets in ciphertext */ |
| 376 | aes_cbc_test_case_0_ciphertext, /* ciphertext */ |
| 377 | NULL /* pointer to next testcase */ |
| 378 | }; |
| 379 | |
| 380 | |
| 381 | /* |
| 382 | * this test case is taken directly from Appendix F.2 of NIST Special |
| 383 | * Publication SP 800-38A |
| 384 | */ |
| 385 | |
| 386 | uint8_t aes_cbc_test_case_1_key[16] = { |
| 387 | 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, |
| 388 | 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c, |
| 389 | }; |
| 390 | |
| 391 | uint8_t aes_cbc_test_case_1_plaintext[64] = { |
| 392 | 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, |
| 393 | 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a, |
| 394 | 0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, |
| 395 | 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51, |
| 396 | 0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, |
| 397 | 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef, |
| 398 | 0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, |
| 399 | 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10 |
| 400 | }; |
| 401 | |
| 402 | uint8_t aes_cbc_test_case_1_ciphertext[80] = { |
| 403 | 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, |
| 404 | 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d, |
| 405 | 0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, |
| 406 | 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2, |
| 407 | 0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, |
| 408 | 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16, |
| 409 | 0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, |
| 410 | 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7, |
| 411 | 0x39, 0x34, 0x07, 0x03, 0x36, 0xd0, 0x77, 0x99, |
| 412 | 0xe0, 0xc4, 0x2f, 0xdd, 0xa8, 0xdf, 0x4c, 0xa3 |
| 413 | }; |
| 414 | |
| 415 | uint8_t aes_cbc_test_case_1_iv[16] = { |
| 416 | 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, |
| 417 | 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f |
| 418 | }; |
| 419 | |
| 420 | cipher_test_case_t aes_cbc_test_case_1 = { |
| 421 | 16, /* octets in key */ |
| 422 | aes_cbc_test_case_1_key, /* key */ |
| 423 | aes_cbc_test_case_1_iv, /* initialization vector */ |
| 424 | 64, /* octets in plaintext */ |
| 425 | aes_cbc_test_case_1_plaintext, /* plaintext */ |
| 426 | 80, /* octets in ciphertext */ |
| 427 | aes_cbc_test_case_1_ciphertext, /* ciphertext */ |
| 428 | &aes_cbc_test_case_0 /* pointer to next testcase */ |
| 429 | }; |
| 430 | |
| 431 | cipher_type_t aes_cbc = { |
| 432 | (cipher_alloc_func_t) aes_cbc_alloc, |
| 433 | (cipher_dealloc_func_t) aes_cbc_dealloc, |
| 434 | (cipher_init_func_t) aes_cbc_context_init, |
| 435 | (cipher_encrypt_func_t) aes_cbc_nist_encrypt, |
| 436 | (cipher_decrypt_func_t) aes_cbc_nist_decrypt, |
| 437 | (cipher_set_iv_func_t) aes_cbc_set_iv, |
| 438 | (char *) aes_cbc_description, |
| 439 | (int) 0, /* instance count */ |
| 440 | (cipher_test_case_t *) &aes_cbc_test_case_0, |
| 441 | (debug_module_t *) &mod_aes_cbc |
| 442 | }; |
| 443 | |
| 444 | |