1 /* 2 * Copyright (c) 2011 The FreeBSD Project. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 */ 25 26 /* Based on: 27 * SHA256-based Unix crypt implementation. Released into the Public Domain by 28 * Ulrich Drepper <drepper@redhat.com>. */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/endian.h> 34 #include <sys/param.h> 35 36 #include <errno.h> 37 #include <limits.h> 38 #include <sha256.h> 39 #include <stdbool.h> 40 #include <stdint.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 45 #include "crypt.h" 46 47 /* Define our magic string to mark salt for SHA256 "encryption" replacement. */ 48 static const char sha256_salt_prefix[] = "$5$"; 49 50 /* Prefix for optional rounds specification. */ 51 static const char sha256_rounds_prefix[] = "rounds="; 52 53 /* Maximum salt string length. */ 54 #define SALT_LEN_MAX 16 55 /* Default number of rounds if not explicitly specified. */ 56 #define ROUNDS_DEFAULT 5000 57 /* Minimum number of rounds. */ 58 #define ROUNDS_MIN 1000 59 /* Maximum number of rounds. */ 60 #define ROUNDS_MAX 999999999 61 62 static char * 63 crypt_sha256_r(const char *key, const char *salt, char *buffer, int buflen) 64 { 65 u_long srounds; 66 int n; 67 uint8_t alt_result[32], temp_result[32]; 68 SHA256_CTX ctx, alt_ctx; 69 size_t salt_len, key_len, cnt, rounds; 70 char *cp, *copied_key, *copied_salt, *p_bytes, *s_bytes, *endp; 71 const char *num; 72 bool rounds_custom; 73 74 copied_key = NULL; 75 copied_salt = NULL; 76 77 /* Default number of rounds. */ 78 rounds = ROUNDS_DEFAULT; 79 rounds_custom = false; 80 81 /* Find beginning of salt string. The prefix should normally always 82 * be present. Just in case it is not. */ 83 if (strncmp(sha256_salt_prefix, salt, sizeof(sha256_salt_prefix) - 1) == 0) 84 /* Skip salt prefix. */ 85 salt += sizeof(sha256_salt_prefix) - 1; 86 87 if (strncmp(salt, sha256_rounds_prefix, sizeof(sha256_rounds_prefix) - 1) 88 == 0) { 89 num = salt + sizeof(sha256_rounds_prefix) - 1; 90 srounds = strtoul(num, &endp, 10); 91 92 if (*endp == '$') { 93 salt = endp + 1; 94 rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX)); 95 rounds_custom = true; 96 } 97 } 98 99 salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX); 100 key_len = strlen(key); 101 102 /* Prepare for the real work. */ 103 SHA256_Init(&ctx); 104 105 /* Add the key string. */ 106 SHA256_Update(&ctx, key, key_len); 107 108 /* The last part is the salt string. This must be at most 8 109 * characters and it ends at the first `$' character (for 110 * compatibility with existing implementations). */ 111 SHA256_Update(&ctx, salt, salt_len); 112 113 /* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The 114 * final result will be added to the first context. */ 115 SHA256_Init(&alt_ctx); 116 117 /* Add key. */ 118 SHA256_Update(&alt_ctx, key, key_len); 119 120 /* Add salt. */ 121 SHA256_Update(&alt_ctx, salt, salt_len); 122 123 /* Add key again. */ 124 SHA256_Update(&alt_ctx, key, key_len); 125 126 /* Now get result of this (32 bytes) and add it to the other context. */ 127 SHA256_Final(alt_result, &alt_ctx); 128 129 /* Add for any character in the key one byte of the alternate sum. */ 130 for (cnt = key_len; cnt > 32; cnt -= 32) 131 SHA256_Update(&ctx, alt_result, 32); 132 SHA256_Update(&ctx, alt_result, cnt); 133 134 /* Take the binary representation of the length of the key and for 135 * every 1 add the alternate sum, for every 0 the key. */ 136 for (cnt = key_len; cnt > 0; cnt >>= 1) 137 if ((cnt & 1) != 0) 138 SHA256_Update(&ctx, alt_result, 32); 139 else 140 SHA256_Update(&ctx, key, key_len); 141 142 /* Create intermediate result. */ 143 SHA256_Final(alt_result, &ctx); 144 145 /* Start computation of P byte sequence. */ 146 SHA256_Init(&alt_ctx); 147 148 /* For every character in the password add the entire password. */ 149 for (cnt = 0; cnt < key_len; ++cnt) 150 SHA256_Update(&alt_ctx, key, key_len); 151 152 /* Finish the digest. */ 153 SHA256_Final(temp_result, &alt_ctx); 154 155 /* Create byte sequence P. */ 156 cp = p_bytes = alloca(key_len); 157 for (cnt = key_len; cnt >= 32; cnt -= 32) { 158 memcpy(cp, temp_result, 32); 159 cp += 32; 160 } 161 memcpy(cp, temp_result, cnt); 162 163 /* Start computation of S byte sequence. */ 164 SHA256_Init(&alt_ctx); 165 166 /* For every character in the password add the entire password. */ 167 for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) 168 SHA256_Update(&alt_ctx, salt, salt_len); 169 170 /* Finish the digest. */ 171 SHA256_Final(temp_result, &alt_ctx); 172 173 /* Create byte sequence S. */ 174 cp = s_bytes = alloca(salt_len); 175 for (cnt = salt_len; cnt >= 32; cnt -= 32) { 176 memcpy(cp, temp_result, 32); 177 cp += 32; 178 } 179 memcpy(cp, temp_result, cnt); 180 181 /* Repeatedly run the collected hash value through SHA256 to burn CPU 182 * cycles. */ 183 for (cnt = 0; cnt < rounds; ++cnt) { 184 /* New context. */ 185 SHA256_Init(&ctx); 186 187 /* Add key or last result. */ 188 if ((cnt & 1) != 0) 189 SHA256_Update(&ctx, p_bytes, key_len); 190 else 191 SHA256_Update(&ctx, alt_result, 32); 192 193 /* Add salt for numbers not divisible by 3. */ 194 if (cnt % 3 != 0) 195 SHA256_Update(&ctx, s_bytes, salt_len); 196 197 /* Add key for numbers not divisible by 7. */ 198 if (cnt % 7 != 0) 199 SHA256_Update(&ctx, p_bytes, key_len); 200 201 /* Add key or last result. */ 202 if ((cnt & 1) != 0) 203 SHA256_Update(&ctx, alt_result, 32); 204 else 205 SHA256_Update(&ctx, p_bytes, key_len); 206 207 /* Create intermediate result. */ 208 SHA256_Final(alt_result, &ctx); 209 } 210 211 /* Now we can construct the result string. It consists of three 212 * parts. */ 213 cp = stpncpy(buffer, sha256_salt_prefix, MAX(0, buflen)); 214 buflen -= sizeof(sha256_salt_prefix) - 1; 215 216 if (rounds_custom) { 217 n = snprintf(cp, MAX(0, buflen), "%s%zu$", 218 sha256_rounds_prefix, rounds); 219 220 cp += n; 221 buflen -= n; 222 } 223 224 cp = stpncpy(cp, salt, MIN((size_t)MAX(0, buflen), salt_len)); 225 buflen -= MIN((size_t)MAX(0, buflen), salt_len); 226 227 if (buflen > 0) { 228 *cp++ = '$'; 229 --buflen; 230 } 231 232 b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4, &buflen, &cp); 233 b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4, &buflen, &cp); 234 b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4, &buflen, &cp); 235 b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4, &buflen, &cp); 236 b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4, &buflen, &cp); 237 b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4, &buflen, &cp); 238 b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4, &buflen, &cp); 239 b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4, &buflen, &cp); 240 b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4, &buflen, &cp); 241 b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4, &buflen, &cp); 242 b64_from_24bit(0, alt_result[31], alt_result[30], 3, &buflen, &cp); 243 if (buflen <= 0) { 244 errno = ERANGE; 245 buffer = NULL; 246 } 247 else 248 *cp = '\0'; /* Terminate the string. */ 249 250 /* Clear the buffer for the intermediate result so that people 251 * attaching to processes or reading core dumps cannot get any 252 * information. We do it in this way to clear correct_words[] inside 253 * the SHA256 implementation as well. */ 254 SHA256_Init(&ctx); 255 SHA256_Final(alt_result, &ctx); 256 memset(temp_result, '\0', sizeof(temp_result)); 257 memset(p_bytes, '\0', key_len); 258 memset(s_bytes, '\0', salt_len); 259 memset(&ctx, '\0', sizeof(ctx)); 260 memset(&alt_ctx, '\0', sizeof(alt_ctx)); 261 if (copied_key != NULL) 262 memset(copied_key, '\0', key_len); 263 if (copied_salt != NULL) 264 memset(copied_salt, '\0', salt_len); 265 266 return buffer; 267 } 268 269 /* This entry point is equivalent to crypt(3). */ 270 char * 271 crypt_sha256(const char *key, const char *salt) 272 { 273 /* We don't want to have an arbitrary limit in the size of the 274 * password. We can compute an upper bound for the size of the 275 * result in advance and so we can prepare the buffer we pass to 276 * `crypt_sha256_r'. */ 277 static char *buffer; 278 static int buflen; 279 int needed; 280 char *new_buffer; 281 282 needed = (sizeof(sha256_salt_prefix) - 1 283 + sizeof(sha256_rounds_prefix) + 9 + 1 284 + strlen(salt) + 1 + 43 + 1); 285 286 if (buflen < needed) { 287 new_buffer = (char *)realloc(buffer, needed); 288 289 if (new_buffer == NULL) 290 return NULL; 291 292 buffer = new_buffer; 293 buflen = needed; 294 } 295 296 return crypt_sha256_r(key, salt, buffer, buflen); 297 } 298 299 #ifdef TEST 300 301 static const struct { 302 const char *input; 303 const char result[32]; 304 } tests[] = 305 { 306 /* Test vectors from FIPS 180-2: appendix B.1. */ 307 { 308 "abc", 309 "\xba\x78\x16\xbf\x8f\x01\xcf\xea\x41\x41\x40\xde\x5d\xae\x22\x23" 310 "\xb0\x03\x61\xa3\x96\x17\x7a\x9c\xb4\x10\xff\x61\xf2\x00\x15\xad" 311 }, 312 /* Test vectors from FIPS 180-2: appendix B.2. */ 313 { 314 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 315 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 316 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 317 }, 318 /* Test vectors from the NESSIE project. */ 319 { 320 "", 321 "\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9\x24" 322 "\x27\xae\x41\xe4\x64\x9b\x93\x4c\xa4\x95\x99\x1b\x78\x52\xb8\x55" 323 }, 324 { 325 "a", 326 "\xca\x97\x81\x12\xca\x1b\xbd\xca\xfa\xc2\x31\xb3\x9a\x23\xdc\x4d" 327 "\xa7\x86\xef\xf8\x14\x7c\x4e\x72\xb9\x80\x77\x85\xaf\xee\x48\xbb" 328 }, 329 { 330 "message digest", 331 "\xf7\x84\x6f\x55\xcf\x23\xe1\x4e\xeb\xea\xb5\xb4\xe1\x55\x0c\xad" 332 "\x5b\x50\x9e\x33\x48\xfb\xc4\xef\xa3\xa1\x41\x3d\x39\x3c\xb6\x50" 333 }, 334 { 335 "abcdefghijklmnopqrstuvwxyz", 336 "\x71\xc4\x80\xdf\x93\xd6\xae\x2f\x1e\xfa\xd1\x44\x7c\x66\xc9\x52" 337 "\x5e\x31\x62\x18\xcf\x51\xfc\x8d\x9e\xd8\x32\xf2\xda\xf1\x8b\x73" 338 }, 339 { 340 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 341 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 342 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 343 }, 344 { 345 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 346 "\xdb\x4b\xfc\xbd\x4d\xa0\xcd\x85\xa6\x0c\x3c\x37\xd3\xfb\xd8\x80" 347 "\x5c\x77\xf1\x5f\xc6\xb1\xfd\xfe\x61\x4e\xe0\xa7\xc8\xfd\xb4\xc0" 348 }, 349 { 350 "123456789012345678901234567890123456789012345678901234567890" 351 "12345678901234567890", 352 "\xf3\x71\xbc\x4a\x31\x1f\x2b\x00\x9e\xef\x95\x2d\xd8\x3c\xa8\x0e" 353 "\x2b\x60\x02\x6c\x8e\x93\x55\x92\xd0\xf9\xc3\x08\x45\x3c\x81\x3e" 354 } 355 }; 356 357 #define ntests (sizeof (tests) / sizeof (tests[0])) 358 359 static const struct { 360 const char *salt; 361 const char *input; 362 const char *expected; 363 } tests2[] = 364 { 365 { 366 "$5$saltstring", "Hello world!", 367 "$5$saltstring$5B8vYYiY.CVt1RlTTf8KbXBH3hsxY/GNooZaBBGWEc5" 368 }, 369 { 370 "$5$rounds=10000$saltstringsaltstring", "Hello world!", 371 "$5$rounds=10000$saltstringsaltst$3xv.VbSHBb41AL9AvLeujZkZRBAwqFMz2." 372 "opqey6IcA" 373 }, 374 { 375 "$5$rounds=5000$toolongsaltstring", "This is just a test", 376 "$5$rounds=5000$toolongsaltstrin$Un/5jzAHMgOGZ5.mWJpuVolil07guHPvOW8" 377 "mGRcvxa5" 378 }, 379 { 380 "$5$rounds=1400$anotherlongsaltstring", 381 "a very much longer text to encrypt. This one even stretches over more" 382 "than one line.", 383 "$5$rounds=1400$anotherlongsalts$Rx.j8H.h8HjEDGomFU8bDkXm3XIUnzyxf12" 384 "oP84Bnq1" 385 }, 386 { 387 "$5$rounds=77777$short", 388 "we have a short salt string but not a short password", 389 "$5$rounds=77777$short$JiO1O3ZpDAxGJeaDIuqCoEFysAe1mZNJRs3pw0KQRd/" 390 }, 391 { 392 "$5$rounds=123456$asaltof16chars..", "a short string", 393 "$5$rounds=123456$asaltof16chars..$gP3VQ/6X7UUEW3HkBn2w1/Ptq2jxPyzV/" 394 "cZKmF/wJvD" 395 }, 396 { 397 "$5$rounds=10$roundstoolow", "the minimum number is still observed", 398 "$5$rounds=1000$roundstoolow$yfvwcWrQ8l/K0DAWyuPMDNHpIVlTQebY9l/gL97" 399 "2bIC" 400 }, 401 }; 402 403 #define ntests2 (sizeof (tests2) / sizeof (tests2[0])) 404 405 int 406 main(void) 407 { 408 SHA256_CTX ctx; 409 uint8_t sum[32]; 410 int result = 0; 411 int i, cnt; 412 413 for (cnt = 0; cnt < (int)ntests; ++cnt) { 414 SHA256_Init(&ctx); 415 SHA256_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input)); 416 SHA256_Final(sum, &ctx); 417 if (memcmp(tests[cnt].result, sum, 32) != 0) { 418 for (i = 0; i < 32; i++) 419 printf("%02X", tests[cnt].result[i]); 420 printf("\n"); 421 for (i = 0; i < 32; i++) 422 printf("%02X", sum[i]); 423 printf("\n"); 424 printf("test %d run %d failed\n", cnt, 1); 425 result = 1; 426 } 427 428 SHA256_Init(&ctx); 429 for (i = 0; tests[cnt].input[i] != '\0'; ++i) 430 SHA256_Update(&ctx, &tests[cnt].input[i], 1); 431 SHA256_Final(sum, &ctx); 432 if (memcmp(tests[cnt].result, sum, 32) != 0) { 433 for (i = 0; i < 32; i++) 434 printf("%02X", tests[cnt].result[i]); 435 printf("\n"); 436 for (i = 0; i < 32; i++) 437 printf("%02X", sum[i]); 438 printf("\n"); 439 printf("test %d run %d failed\n", cnt, 2); 440 result = 1; 441 } 442 } 443 444 /* Test vector from FIPS 180-2: appendix B.3. */ 445 char buf[1000]; 446 447 memset(buf, 'a', sizeof(buf)); 448 SHA256_Init(&ctx); 449 for (i = 0; i < 1000; ++i) 450 SHA256_Update(&ctx, buf, sizeof(buf)); 451 SHA256_Final(sum, &ctx); 452 static const char expected[32] = 453 "\xcd\xc7\x6e\x5c\x99\x14\xfb\x92\x81\xa1\xc7\xe2\x84\xd7\x3e\x67" 454 "\xf1\x80\x9a\x48\xa4\x97\x20\x0e\x04\x6d\x39\xcc\xc7\x11\x2c\xd0"; 455 456 if (memcmp(expected, sum, 32) != 0) { 457 printf("test %d failed\n", cnt); 458 result = 1; 459 } 460 461 for (cnt = 0; cnt < ntests2; ++cnt) { 462 char *cp = crypt_sha256(tests2[cnt].input, tests2[cnt].salt); 463 464 if (strcmp(cp, tests2[cnt].expected) != 0) { 465 printf("test %d: expected \"%s\", got \"%s\"\n", 466 cnt, tests2[cnt].expected, cp); 467 result = 1; 468 } 469 } 470 471 if (result == 0) 472 puts("all tests OK"); 473 474 return result; 475 } 476 477 #endif /* TEST */ 478