crypt-sha256.c revision 330897
1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2011 The FreeBSD Project. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28/* Based on: 29 * SHA256-based Unix crypt implementation. Released into the Public Domain by 30 * Ulrich Drepper <drepper@redhat.com>. */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: stable/11/lib/libcrypt/crypt-sha256.c 330897 2018-03-14 03:19:51Z eadler $"); 34 35#include <sys/endian.h> 36#include <sys/param.h> 37 38#include <errno.h> 39#include <limits.h> 40#include <sha256.h> 41#include <stdbool.h> 42#include <stdint.h> 43#include <stdio.h> 44#include <stdlib.h> 45#include <string.h> 46 47#include "crypt.h" 48 49/* Define our magic string to mark salt for SHA256 "encryption" replacement. */ 50static const char sha256_salt_prefix[] = "$5$"; 51 52/* Prefix for optional rounds specification. */ 53static const char sha256_rounds_prefix[] = "rounds="; 54 55/* Maximum salt string length. */ 56#define SALT_LEN_MAX 16 57/* Default number of rounds if not explicitly specified. */ 58#define ROUNDS_DEFAULT 5000 59/* Minimum number of rounds. */ 60#define ROUNDS_MIN 1000 61/* Maximum number of rounds. */ 62#define ROUNDS_MAX 999999999 63 64static char * 65crypt_sha256_r(const char *key, const char *salt, char *buffer, int buflen) 66{ 67 u_long srounds; 68 int n; 69 uint8_t alt_result[32], temp_result[32]; 70 SHA256_CTX ctx, alt_ctx; 71 size_t salt_len, key_len, cnt, rounds; 72 char *cp, *copied_key, *copied_salt, *p_bytes, *s_bytes, *endp; 73 const char *num; 74 bool rounds_custom; 75 76 copied_key = NULL; 77 copied_salt = NULL; 78 79 /* Default number of rounds. */ 80 rounds = ROUNDS_DEFAULT; 81 rounds_custom = false; 82 83 /* Find beginning of salt string. The prefix should normally always 84 * be present. Just in case it is not. */ 85 if (strncmp(sha256_salt_prefix, salt, sizeof(sha256_salt_prefix) - 1) == 0) 86 /* Skip salt prefix. */ 87 salt += sizeof(sha256_salt_prefix) - 1; 88 89 if (strncmp(salt, sha256_rounds_prefix, sizeof(sha256_rounds_prefix) - 1) 90 == 0) { 91 num = salt + sizeof(sha256_rounds_prefix) - 1; 92 srounds = strtoul(num, &endp, 10); 93 94 if (*endp == '$') { 95 salt = endp + 1; 96 rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX)); 97 rounds_custom = true; 98 } 99 } 100 101 salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX); 102 key_len = strlen(key); 103 104 /* Prepare for the real work. */ 105 SHA256_Init(&ctx); 106 107 /* Add the key string. */ 108 SHA256_Update(&ctx, key, key_len); 109 110 /* The last part is the salt string. This must be at most 8 111 * characters and it ends at the first `$' character (for 112 * compatibility with existing implementations). */ 113 SHA256_Update(&ctx, salt, salt_len); 114 115 /* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The 116 * final result will be added to the first context. */ 117 SHA256_Init(&alt_ctx); 118 119 /* Add key. */ 120 SHA256_Update(&alt_ctx, key, key_len); 121 122 /* Add salt. */ 123 SHA256_Update(&alt_ctx, salt, salt_len); 124 125 /* Add key again. */ 126 SHA256_Update(&alt_ctx, key, key_len); 127 128 /* Now get result of this (32 bytes) and add it to the other context. */ 129 SHA256_Final(alt_result, &alt_ctx); 130 131 /* Add for any character in the key one byte of the alternate sum. */ 132 for (cnt = key_len; cnt > 32; cnt -= 32) 133 SHA256_Update(&ctx, alt_result, 32); 134 SHA256_Update(&ctx, alt_result, cnt); 135 136 /* Take the binary representation of the length of the key and for 137 * every 1 add the alternate sum, for every 0 the key. */ 138 for (cnt = key_len; cnt > 0; cnt >>= 1) 139 if ((cnt & 1) != 0) 140 SHA256_Update(&ctx, alt_result, 32); 141 else 142 SHA256_Update(&ctx, key, key_len); 143 144 /* Create intermediate result. */ 145 SHA256_Final(alt_result, &ctx); 146 147 /* Start computation of P byte sequence. */ 148 SHA256_Init(&alt_ctx); 149 150 /* For every character in the password add the entire password. */ 151 for (cnt = 0; cnt < key_len; ++cnt) 152 SHA256_Update(&alt_ctx, key, key_len); 153 154 /* Finish the digest. */ 155 SHA256_Final(temp_result, &alt_ctx); 156 157 /* Create byte sequence P. */ 158 cp = p_bytes = alloca(key_len); 159 for (cnt = key_len; cnt >= 32; cnt -= 32) { 160 memcpy(cp, temp_result, 32); 161 cp += 32; 162 } 163 memcpy(cp, temp_result, cnt); 164 165 /* Start computation of S byte sequence. */ 166 SHA256_Init(&alt_ctx); 167 168 /* For every character in the password add the entire password. */ 169 for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) 170 SHA256_Update(&alt_ctx, salt, salt_len); 171 172 /* Finish the digest. */ 173 SHA256_Final(temp_result, &alt_ctx); 174 175 /* Create byte sequence S. */ 176 cp = s_bytes = alloca(salt_len); 177 for (cnt = salt_len; cnt >= 32; cnt -= 32) { 178 memcpy(cp, temp_result, 32); 179 cp += 32; 180 } 181 memcpy(cp, temp_result, cnt); 182 183 /* Repeatedly run the collected hash value through SHA256 to burn CPU 184 * cycles. */ 185 for (cnt = 0; cnt < rounds; ++cnt) { 186 /* New context. */ 187 SHA256_Init(&ctx); 188 189 /* Add key or last result. */ 190 if ((cnt & 1) != 0) 191 SHA256_Update(&ctx, p_bytes, key_len); 192 else 193 SHA256_Update(&ctx, alt_result, 32); 194 195 /* Add salt for numbers not divisible by 3. */ 196 if (cnt % 3 != 0) 197 SHA256_Update(&ctx, s_bytes, salt_len); 198 199 /* Add key for numbers not divisible by 7. */ 200 if (cnt % 7 != 0) 201 SHA256_Update(&ctx, p_bytes, key_len); 202 203 /* Add key or last result. */ 204 if ((cnt & 1) != 0) 205 SHA256_Update(&ctx, alt_result, 32); 206 else 207 SHA256_Update(&ctx, p_bytes, key_len); 208 209 /* Create intermediate result. */ 210 SHA256_Final(alt_result, &ctx); 211 } 212 213 /* Now we can construct the result string. It consists of three 214 * parts. */ 215 cp = stpncpy(buffer, sha256_salt_prefix, MAX(0, buflen)); 216 buflen -= sizeof(sha256_salt_prefix) - 1; 217 218 if (rounds_custom) { 219 n = snprintf(cp, MAX(0, buflen), "%s%zu$", 220 sha256_rounds_prefix, rounds); 221 222 cp += n; 223 buflen -= n; 224 } 225 226 cp = stpncpy(cp, salt, MIN((size_t)MAX(0, buflen), salt_len)); 227 buflen -= MIN((size_t)MAX(0, buflen), salt_len); 228 229 if (buflen > 0) { 230 *cp++ = '$'; 231 --buflen; 232 } 233 234 b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4, &buflen, &cp); 235 b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4, &buflen, &cp); 236 b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4, &buflen, &cp); 237 b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4, &buflen, &cp); 238 b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4, &buflen, &cp); 239 b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4, &buflen, &cp); 240 b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4, &buflen, &cp); 241 b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4, &buflen, &cp); 242 b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4, &buflen, &cp); 243 b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4, &buflen, &cp); 244 b64_from_24bit(0, alt_result[31], alt_result[30], 3, &buflen, &cp); 245 if (buflen <= 0) { 246 errno = ERANGE; 247 buffer = NULL; 248 } 249 else 250 *cp = '\0'; /* Terminate the string. */ 251 252 /* Clear the buffer for the intermediate result so that people 253 * attaching to processes or reading core dumps cannot get any 254 * information. We do it in this way to clear correct_words[] inside 255 * the SHA256 implementation as well. */ 256 SHA256_Init(&ctx); 257 SHA256_Final(alt_result, &ctx); 258 memset(temp_result, '\0', sizeof(temp_result)); 259 memset(p_bytes, '\0', key_len); 260 memset(s_bytes, '\0', salt_len); 261 memset(&ctx, '\0', sizeof(ctx)); 262 memset(&alt_ctx, '\0', sizeof(alt_ctx)); 263 if (copied_key != NULL) 264 memset(copied_key, '\0', key_len); 265 if (copied_salt != NULL) 266 memset(copied_salt, '\0', salt_len); 267 268 return buffer; 269} 270 271/* This entry point is equivalent to crypt(3). */ 272char * 273crypt_sha256(const char *key, const char *salt) 274{ 275 /* We don't want to have an arbitrary limit in the size of the 276 * password. We can compute an upper bound for the size of the 277 * result in advance and so we can prepare the buffer we pass to 278 * `crypt_sha256_r'. */ 279 static char *buffer; 280 static int buflen; 281 int needed; 282 char *new_buffer; 283 284 needed = (sizeof(sha256_salt_prefix) - 1 285 + sizeof(sha256_rounds_prefix) + 9 + 1 286 + strlen(salt) + 1 + 43 + 1); 287 288 if (buflen < needed) { 289 new_buffer = (char *)realloc(buffer, needed); 290 291 if (new_buffer == NULL) 292 return NULL; 293 294 buffer = new_buffer; 295 buflen = needed; 296 } 297 298 return crypt_sha256_r(key, salt, buffer, buflen); 299} 300 301#ifdef TEST 302 303static const struct { 304 const char *input; 305 const char result[32]; 306} tests[] = 307{ 308 /* Test vectors from FIPS 180-2: appendix B.1. */ 309 { 310 "abc", 311 "\xba\x78\x16\xbf\x8f\x01\xcf\xea\x41\x41\x40\xde\x5d\xae\x22\x23" 312 "\xb0\x03\x61\xa3\x96\x17\x7a\x9c\xb4\x10\xff\x61\xf2\x00\x15\xad" 313 }, 314 /* Test vectors from FIPS 180-2: appendix B.2. */ 315 { 316 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 317 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 318 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 319 }, 320 /* Test vectors from the NESSIE project. */ 321 { 322 "", 323 "\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9\x24" 324 "\x27\xae\x41\xe4\x64\x9b\x93\x4c\xa4\x95\x99\x1b\x78\x52\xb8\x55" 325 }, 326 { 327 "a", 328 "\xca\x97\x81\x12\xca\x1b\xbd\xca\xfa\xc2\x31\xb3\x9a\x23\xdc\x4d" 329 "\xa7\x86\xef\xf8\x14\x7c\x4e\x72\xb9\x80\x77\x85\xaf\xee\x48\xbb" 330 }, 331 { 332 "message digest", 333 "\xf7\x84\x6f\x55\xcf\x23\xe1\x4e\xeb\xea\xb5\xb4\xe1\x55\x0c\xad" 334 "\x5b\x50\x9e\x33\x48\xfb\xc4\xef\xa3\xa1\x41\x3d\x39\x3c\xb6\x50" 335 }, 336 { 337 "abcdefghijklmnopqrstuvwxyz", 338 "\x71\xc4\x80\xdf\x93\xd6\xae\x2f\x1e\xfa\xd1\x44\x7c\x66\xc9\x52" 339 "\x5e\x31\x62\x18\xcf\x51\xfc\x8d\x9e\xd8\x32\xf2\xda\xf1\x8b\x73" 340 }, 341 { 342 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 343 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 344 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 345 }, 346 { 347 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 348 "\xdb\x4b\xfc\xbd\x4d\xa0\xcd\x85\xa6\x0c\x3c\x37\xd3\xfb\xd8\x80" 349 "\x5c\x77\xf1\x5f\xc6\xb1\xfd\xfe\x61\x4e\xe0\xa7\xc8\xfd\xb4\xc0" 350 }, 351 { 352 "123456789012345678901234567890123456789012345678901234567890" 353 "12345678901234567890", 354 "\xf3\x71\xbc\x4a\x31\x1f\x2b\x00\x9e\xef\x95\x2d\xd8\x3c\xa8\x0e" 355 "\x2b\x60\x02\x6c\x8e\x93\x55\x92\xd0\xf9\xc3\x08\x45\x3c\x81\x3e" 356 } 357}; 358 359#define ntests (sizeof (tests) / sizeof (tests[0])) 360 361static const struct { 362 const char *salt; 363 const char *input; 364 const char *expected; 365} tests2[] = 366{ 367 { 368 "$5$saltstring", "Hello world!", 369 "$5$saltstring$5B8vYYiY.CVt1RlTTf8KbXBH3hsxY/GNooZaBBGWEc5" 370 }, 371 { 372 "$5$rounds=10000$saltstringsaltstring", "Hello world!", 373 "$5$rounds=10000$saltstringsaltst$3xv.VbSHBb41AL9AvLeujZkZRBAwqFMz2." 374 "opqey6IcA" 375 }, 376 { 377 "$5$rounds=5000$toolongsaltstring", "This is just a test", 378 "$5$rounds=5000$toolongsaltstrin$Un/5jzAHMgOGZ5.mWJpuVolil07guHPvOW8" 379 "mGRcvxa5" 380 }, 381 { 382 "$5$rounds=1400$anotherlongsaltstring", 383 "a very much longer text to encrypt. This one even stretches over more" 384 "than one line.", 385 "$5$rounds=1400$anotherlongsalts$Rx.j8H.h8HjEDGomFU8bDkXm3XIUnzyxf12" 386 "oP84Bnq1" 387 }, 388 { 389 "$5$rounds=77777$short", 390 "we have a short salt string but not a short password", 391 "$5$rounds=77777$short$JiO1O3ZpDAxGJeaDIuqCoEFysAe1mZNJRs3pw0KQRd/" 392 }, 393 { 394 "$5$rounds=123456$asaltof16chars..", "a short string", 395 "$5$rounds=123456$asaltof16chars..$gP3VQ/6X7UUEW3HkBn2w1/Ptq2jxPyzV/" 396 "cZKmF/wJvD" 397 }, 398 { 399 "$5$rounds=10$roundstoolow", "the minimum number is still observed", 400 "$5$rounds=1000$roundstoolow$yfvwcWrQ8l/K0DAWyuPMDNHpIVlTQebY9l/gL97" 401 "2bIC" 402 }, 403}; 404 405#define ntests2 (sizeof (tests2) / sizeof (tests2[0])) 406 407int 408main(void) 409{ 410 SHA256_CTX ctx; 411 uint8_t sum[32]; 412 int result = 0; 413 int i, cnt; 414 415 for (cnt = 0; cnt < (int)ntests; ++cnt) { 416 SHA256_Init(&ctx); 417 SHA256_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input)); 418 SHA256_Final(sum, &ctx); 419 if (memcmp(tests[cnt].result, sum, 32) != 0) { 420 for (i = 0; i < 32; i++) 421 printf("%02X", tests[cnt].result[i]); 422 printf("\n"); 423 for (i = 0; i < 32; i++) 424 printf("%02X", sum[i]); 425 printf("\n"); 426 printf("test %d run %d failed\n", cnt, 1); 427 result = 1; 428 } 429 430 SHA256_Init(&ctx); 431 for (i = 0; tests[cnt].input[i] != '\0'; ++i) 432 SHA256_Update(&ctx, &tests[cnt].input[i], 1); 433 SHA256_Final(sum, &ctx); 434 if (memcmp(tests[cnt].result, sum, 32) != 0) { 435 for (i = 0; i < 32; i++) 436 printf("%02X", tests[cnt].result[i]); 437 printf("\n"); 438 for (i = 0; i < 32; i++) 439 printf("%02X", sum[i]); 440 printf("\n"); 441 printf("test %d run %d failed\n", cnt, 2); 442 result = 1; 443 } 444 } 445 446 /* Test vector from FIPS 180-2: appendix B.3. */ 447 char buf[1000]; 448 449 memset(buf, 'a', sizeof(buf)); 450 SHA256_Init(&ctx); 451 for (i = 0; i < 1000; ++i) 452 SHA256_Update(&ctx, buf, sizeof(buf)); 453 SHA256_Final(sum, &ctx); 454 static const char expected[32] = 455 "\xcd\xc7\x6e\x5c\x99\x14\xfb\x92\x81\xa1\xc7\xe2\x84\xd7\x3e\x67" 456 "\xf1\x80\x9a\x48\xa4\x97\x20\x0e\x04\x6d\x39\xcc\xc7\x11\x2c\xd0"; 457 458 if (memcmp(expected, sum, 32) != 0) { 459 printf("test %d failed\n", cnt); 460 result = 1; 461 } 462 463 for (cnt = 0; cnt < ntests2; ++cnt) { 464 char *cp = crypt_sha256(tests2[cnt].input, tests2[cnt].salt); 465 466 if (strcmp(cp, tests2[cnt].expected) != 0) { 467 printf("test %d: expected \"%s\", got \"%s\"\n", 468 cnt, tests2[cnt].expected, cp); 469 result = 1; 470 } 471 } 472 473 if (result == 0) 474 puts("all tests OK"); 475 476 return result; 477} 478 479#endif /* TEST */ 480