1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #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 #include <strings.h> 45 46 #include "crypt.h" 47 48 /* Define our magic string to mark salt for SHA256 "encryption" replacement. */ 49 static const char sha256_salt_prefix[] = "$5$"; 50 51 /* Prefix for optional rounds specification. */ 52 static const char sha256_rounds_prefix[] = "rounds="; 53 54 /* Maximum salt string length. */ 55 #define SALT_LEN_MAX 16 56 /* Default number of rounds if not explicitly specified. */ 57 #define ROUNDS_DEFAULT 5000 58 /* Minimum number of rounds. */ 59 #define ROUNDS_MIN 1000 60 /* Maximum number of rounds. */ 61 #define ROUNDS_MAX 999999999 62 63 int 64 crypt_sha256(const char *key, const char *salt, char *buffer) 65 { 66 u_long srounds; 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, *p_bytes, *s_bytes, *endp; 71 const char *num; 72 bool rounds_custom; 73 74 /* Default number of rounds. */ 75 rounds = ROUNDS_DEFAULT; 76 rounds_custom = false; 77 78 /* Find beginning of salt string. The prefix should normally always 79 * be present. Just in case it is not. */ 80 if (strncmp(sha256_salt_prefix, salt, sizeof(sha256_salt_prefix) - 1) == 0) 81 /* Skip salt prefix. */ 82 salt += sizeof(sha256_salt_prefix) - 1; 83 84 if (strncmp(salt, sha256_rounds_prefix, sizeof(sha256_rounds_prefix) - 1) 85 == 0) { 86 num = salt + sizeof(sha256_rounds_prefix) - 1; 87 srounds = strtoul(num, &endp, 10); 88 89 if (*endp == '$') { 90 salt = endp + 1; 91 rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX)); 92 rounds_custom = true; 93 } 94 } 95 96 salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX); 97 key_len = strlen(key); 98 99 /* Prepare for the real work. */ 100 SHA256_Init(&ctx); 101 102 /* Add the key string. */ 103 SHA256_Update(&ctx, key, key_len); 104 105 /* The last part is the salt string. This must be at most 8 106 * characters and it ends at the first `$' character (for 107 * compatibility with existing implementations). */ 108 SHA256_Update(&ctx, salt, salt_len); 109 110 /* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The 111 * final result will be added to the first context. */ 112 SHA256_Init(&alt_ctx); 113 114 /* Add key. */ 115 SHA256_Update(&alt_ctx, key, key_len); 116 117 /* Add salt. */ 118 SHA256_Update(&alt_ctx, salt, salt_len); 119 120 /* Add key again. */ 121 SHA256_Update(&alt_ctx, key, key_len); 122 123 /* Now get result of this (32 bytes) and add it to the other context. */ 124 SHA256_Final(alt_result, &alt_ctx); 125 126 /* Add for any character in the key one byte of the alternate sum. */ 127 for (cnt = key_len; cnt > 32; cnt -= 32) 128 SHA256_Update(&ctx, alt_result, 32); 129 SHA256_Update(&ctx, alt_result, cnt); 130 131 /* Take the binary representation of the length of the key and for 132 * every 1 add the alternate sum, for every 0 the key. */ 133 for (cnt = key_len; cnt > 0; cnt >>= 1) 134 if ((cnt & 1) != 0) 135 SHA256_Update(&ctx, alt_result, 32); 136 else 137 SHA256_Update(&ctx, key, key_len); 138 139 /* Create intermediate result. */ 140 SHA256_Final(alt_result, &ctx); 141 142 /* Start computation of P byte sequence. */ 143 SHA256_Init(&alt_ctx); 144 145 /* For every character in the password add the entire password. */ 146 for (cnt = 0; cnt < key_len; ++cnt) 147 SHA256_Update(&alt_ctx, key, key_len); 148 149 /* Finish the digest. */ 150 SHA256_Final(temp_result, &alt_ctx); 151 152 /* Create byte sequence P. */ 153 cp = p_bytes = alloca(key_len); 154 for (cnt = key_len; cnt >= 32; cnt -= 32) { 155 memcpy(cp, temp_result, 32); 156 cp += 32; 157 } 158 memcpy(cp, temp_result, cnt); 159 160 /* Start computation of S byte sequence. */ 161 SHA256_Init(&alt_ctx); 162 163 /* For every character in the password add the entire password. */ 164 for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) 165 SHA256_Update(&alt_ctx, salt, salt_len); 166 167 /* Finish the digest. */ 168 SHA256_Final(temp_result, &alt_ctx); 169 170 /* Create byte sequence S. */ 171 cp = s_bytes = alloca(salt_len); 172 for (cnt = salt_len; cnt >= 32; cnt -= 32) { 173 memcpy(cp, temp_result, 32); 174 cp += 32; 175 } 176 memcpy(cp, temp_result, cnt); 177 178 /* Repeatedly run the collected hash value through SHA256 to burn CPU 179 * cycles. */ 180 for (cnt = 0; cnt < rounds; ++cnt) { 181 /* New context. */ 182 SHA256_Init(&ctx); 183 184 /* Add key or last result. */ 185 if ((cnt & 1) != 0) 186 SHA256_Update(&ctx, p_bytes, key_len); 187 else 188 SHA256_Update(&ctx, alt_result, 32); 189 190 /* Add salt for numbers not divisible by 3. */ 191 if (cnt % 3 != 0) 192 SHA256_Update(&ctx, s_bytes, salt_len); 193 194 /* Add key for numbers not divisible by 7. */ 195 if (cnt % 7 != 0) 196 SHA256_Update(&ctx, p_bytes, key_len); 197 198 /* Add key or last result. */ 199 if ((cnt & 1) != 0) 200 SHA256_Update(&ctx, alt_result, 32); 201 else 202 SHA256_Update(&ctx, p_bytes, key_len); 203 204 /* Create intermediate result. */ 205 SHA256_Final(alt_result, &ctx); 206 } 207 208 /* Now we can construct the result string. It consists of three 209 * parts. */ 210 cp = stpcpy(buffer, sha256_salt_prefix); 211 212 if (rounds_custom) 213 cp += sprintf(cp, "%s%zu$", sha256_rounds_prefix, rounds); 214 215 cp = stpncpy(cp, salt, salt_len); 216 217 *cp++ = '$'; 218 219 b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4, &cp); 220 b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4, &cp); 221 b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4, &cp); 222 b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4, &cp); 223 b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4, &cp); 224 b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4, &cp); 225 b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4, &cp); 226 b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4, &cp); 227 b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4, &cp); 228 b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4, &cp); 229 b64_from_24bit(0, alt_result[31], alt_result[30], 3, &cp); 230 *cp = '\0'; /* Terminate the string. */ 231 232 /* Clear the buffer for the intermediate result so that people 233 * attaching to processes or reading core dumps cannot get any 234 * information. We do it in this way to clear correct_words[] inside 235 * the SHA256 implementation as well. */ 236 SHA256_Init(&ctx); 237 SHA256_Final(alt_result, &ctx); 238 explicit_bzero(temp_result, sizeof(temp_result)); 239 explicit_bzero(p_bytes, key_len); 240 explicit_bzero(s_bytes, salt_len); 241 242 return (0); 243 } 244 245 #ifdef TEST 246 247 static const struct { 248 const char *input; 249 const char result[32]; 250 } tests[] = 251 { 252 /* Test vectors from FIPS 180-2: appendix B.1. */ 253 { 254 "abc", 255 "\xba\x78\x16\xbf\x8f\x01\xcf\xea\x41\x41\x40\xde\x5d\xae\x22\x23" 256 "\xb0\x03\x61\xa3\x96\x17\x7a\x9c\xb4\x10\xff\x61\xf2\x00\x15\xad" 257 }, 258 /* Test vectors from FIPS 180-2: appendix B.2. */ 259 { 260 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 261 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 262 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 263 }, 264 /* Test vectors from the NESSIE project. */ 265 { 266 "", 267 "\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9\x24" 268 "\x27\xae\x41\xe4\x64\x9b\x93\x4c\xa4\x95\x99\x1b\x78\x52\xb8\x55" 269 }, 270 { 271 "a", 272 "\xca\x97\x81\x12\xca\x1b\xbd\xca\xfa\xc2\x31\xb3\x9a\x23\xdc\x4d" 273 "\xa7\x86\xef\xf8\x14\x7c\x4e\x72\xb9\x80\x77\x85\xaf\xee\x48\xbb" 274 }, 275 { 276 "message digest", 277 "\xf7\x84\x6f\x55\xcf\x23\xe1\x4e\xeb\xea\xb5\xb4\xe1\x55\x0c\xad" 278 "\x5b\x50\x9e\x33\x48\xfb\xc4\xef\xa3\xa1\x41\x3d\x39\x3c\xb6\x50" 279 }, 280 { 281 "abcdefghijklmnopqrstuvwxyz", 282 "\x71\xc4\x80\xdf\x93\xd6\xae\x2f\x1e\xfa\xd1\x44\x7c\x66\xc9\x52" 283 "\x5e\x31\x62\x18\xcf\x51\xfc\x8d\x9e\xd8\x32\xf2\xda\xf1\x8b\x73" 284 }, 285 { 286 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 287 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39" 288 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1" 289 }, 290 { 291 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 292 "\xdb\x4b\xfc\xbd\x4d\xa0\xcd\x85\xa6\x0c\x3c\x37\xd3\xfb\xd8\x80" 293 "\x5c\x77\xf1\x5f\xc6\xb1\xfd\xfe\x61\x4e\xe0\xa7\xc8\xfd\xb4\xc0" 294 }, 295 { 296 "123456789012345678901234567890123456789012345678901234567890" 297 "12345678901234567890", 298 "\xf3\x71\xbc\x4a\x31\x1f\x2b\x00\x9e\xef\x95\x2d\xd8\x3c\xa8\x0e" 299 "\x2b\x60\x02\x6c\x8e\x93\x55\x92\xd0\xf9\xc3\x08\x45\x3c\x81\x3e" 300 } 301 }; 302 303 #define ntests (sizeof (tests) / sizeof (tests[0])) 304 305 static const struct { 306 const char *salt; 307 const char *input; 308 const char *expected; 309 } tests2[] = 310 { 311 { 312 "$5$saltstring", "Hello world!", 313 "$5$saltstring$5B8vYYiY.CVt1RlTTf8KbXBH3hsxY/GNooZaBBGWEc5" 314 }, 315 { 316 "$5$rounds=10000$saltstringsaltstring", "Hello world!", 317 "$5$rounds=10000$saltstringsaltst$3xv.VbSHBb41AL9AvLeujZkZRBAwqFMz2." 318 "opqey6IcA" 319 }, 320 { 321 "$5$rounds=5000$toolongsaltstring", "This is just a test", 322 "$5$rounds=5000$toolongsaltstrin$Un/5jzAHMgOGZ5.mWJpuVolil07guHPvOW8" 323 "mGRcvxa5" 324 }, 325 { 326 "$5$rounds=1400$anotherlongsaltstring", 327 "a very much longer text to encrypt. This one even stretches over more" 328 "than one line.", 329 "$5$rounds=1400$anotherlongsalts$Rx.j8H.h8HjEDGomFU8bDkXm3XIUnzyxf12" 330 "oP84Bnq1" 331 }, 332 { 333 "$5$rounds=77777$short", 334 "we have a short salt string but not a short password", 335 "$5$rounds=77777$short$JiO1O3ZpDAxGJeaDIuqCoEFysAe1mZNJRs3pw0KQRd/" 336 }, 337 { 338 "$5$rounds=123456$asaltof16chars..", "a short string", 339 "$5$rounds=123456$asaltof16chars..$gP3VQ/6X7UUEW3HkBn2w1/Ptq2jxPyzV/" 340 "cZKmF/wJvD" 341 }, 342 { 343 "$5$rounds=10$roundstoolow", "the minimum number is still observed", 344 "$5$rounds=1000$roundstoolow$yfvwcWrQ8l/K0DAWyuPMDNHpIVlTQebY9l/gL97" 345 "2bIC" 346 }, 347 }; 348 349 #define ntests2 (sizeof (tests2) / sizeof (tests2[0])) 350 351 int 352 main(void) 353 { 354 SHA256_CTX ctx; 355 uint8_t sum[32]; 356 int result = 0; 357 int i, cnt; 358 359 for (cnt = 0; cnt < (int)ntests; ++cnt) { 360 SHA256_Init(&ctx); 361 SHA256_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input)); 362 SHA256_Final(sum, &ctx); 363 if (memcmp(tests[cnt].result, sum, 32) != 0) { 364 for (i = 0; i < 32; i++) 365 printf("%02X", tests[cnt].result[i]); 366 printf("\n"); 367 for (i = 0; i < 32; i++) 368 printf("%02X", sum[i]); 369 printf("\n"); 370 printf("test %d run %d failed\n", cnt, 1); 371 result = 1; 372 } 373 374 SHA256_Init(&ctx); 375 for (i = 0; tests[cnt].input[i] != '\0'; ++i) 376 SHA256_Update(&ctx, &tests[cnt].input[i], 1); 377 SHA256_Final(sum, &ctx); 378 if (memcmp(tests[cnt].result, sum, 32) != 0) { 379 for (i = 0; i < 32; i++) 380 printf("%02X", tests[cnt].result[i]); 381 printf("\n"); 382 for (i = 0; i < 32; i++) 383 printf("%02X", sum[i]); 384 printf("\n"); 385 printf("test %d run %d failed\n", cnt, 2); 386 result = 1; 387 } 388 } 389 390 /* Test vector from FIPS 180-2: appendix B.3. */ 391 char buf[1000]; 392 393 memset(buf, 'a', sizeof(buf)); 394 SHA256_Init(&ctx); 395 for (i = 0; i < 1000; ++i) 396 SHA256_Update(&ctx, buf, sizeof(buf)); 397 SHA256_Final(sum, &ctx); 398 static const char expected[32] = 399 "\xcd\xc7\x6e\x5c\x99\x14\xfb\x92\x81\xa1\xc7\xe2\x84\xd7\x3e\x67" 400 "\xf1\x80\x9a\x48\xa4\x97\x20\x0e\x04\x6d\x39\xcc\xc7\x11\x2c\xd0"; 401 402 if (memcmp(expected, sum, 32) != 0) { 403 printf("test %d failed\n", cnt); 404 result = 1; 405 } 406 407 for (cnt = 0; cnt < ntests2; ++cnt) { 408 char *cp = crypt_sha256(tests2[cnt].input, tests2[cnt].salt); 409 410 if (strcmp(cp, tests2[cnt].expected) != 0) { 411 printf("test %d: expected \"%s\", got \"%s\"\n", 412 cnt, tests2[cnt].expected, cp); 413 result = 1; 414 } 415 } 416 417 if (result == 0) 418 puts("all tests OK"); 419 420 return result; 421 } 422 423 #endif /* TEST */ 424