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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 | /* One way encryption based on SHA512 sum. Copyright (C) 2007, 2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@redhat.com>, 2007. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ #include <assert.h> #include <errno.h> #include <stdbool.h> #include <stdlib.h> #include <string.h> #include <sys/param.h> #include "sha512.h" #include "libcrypt.h" /* Define our magic string to mark salt for SHA512 "encryption" replacement. */ static const char sha512_salt_prefix[] = "$6$"; /* Prefix for optional rounds specification. */ static const char sha512_rounds_prefix[] = "rounds="; /* Maximum salt string length. */ #define SALT_LEN_MAX 16 /* Default number of rounds if not explicitly specified. */ #define ROUNDS_DEFAULT 5000 /* Minimum number of rounds. */ #define ROUNDS_MIN 1000 /* Maximum number of rounds. */ #define ROUNDS_MAX 999999999 /* Table with characters for base64 transformation. */ static const char b64t[64] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; #define B64_FROM_24BIT(b2, b1, b0, steps) \ { \ int n = (steps); \ unsigned int w = ((b2) << 16) | ((b1) << 8) | (b0); \ while (n-- > 0 && buflen > 0) \ { \ *cp++ = b64t[w & 0x3f]; \ --buflen; \ w >>= 6; \ } \ } char * __sha512_crypt_r (const char *key, const char *salt, char *buffer, int buflen) { unsigned char alt_result[64] __attribute__ ((__aligned__ (__alignof__ (uint64_t)))); unsigned char temp_result[64] __attribute__ ((__aligned__ (__alignof__ (uint64_t)))); size_t salt_len; size_t key_len; size_t cnt; char *cp; char *copied_key = NULL; char *copied_salt = NULL; char *p_bytes; char *s_bytes; /* Default number of rounds. */ size_t rounds = ROUNDS_DEFAULT; bool rounds_custom = false; /* Find beginning of salt string. The prefix should normally always be present. Just in case it is not. */ if (strncmp (sha512_salt_prefix, salt, sizeof (sha512_salt_prefix) - 1) == 0) /* Skip salt prefix. */ salt += sizeof (sha512_salt_prefix) - 1; if (strncmp (salt, sha512_rounds_prefix, sizeof (sha512_rounds_prefix) - 1) == 0) { const char *num = salt + sizeof (sha512_rounds_prefix) - 1; char *endp; unsigned long int srounds = strtoul (num, &endp, 10); if (*endp == '$') { salt = endp + 1; rounds = MAX (ROUNDS_MIN, MIN (srounds, ROUNDS_MAX)); rounds_custom = true; } } salt_len = MIN (strcspn (salt, "$"), SALT_LEN_MAX); key_len = strlen (key); if ((uintptr_t)key % __alignof__ (uint64_t) != 0) { char *tmp = (char *) alloca (key_len + __alignof__ (uint64_t)); key = copied_key = memcpy (tmp + __alignof__ (uint64_t) - (uintptr_t)tmp % __alignof__ (uint64_t), key, key_len); assert ((key - (char *) 0) % __alignof__ (uint64_t) == 0); } if ((uintptr_t)salt % __alignof__ (uint64_t) != 0) { char *tmp = (char *) alloca (salt_len + __alignof__ (uint64_t)); salt = copied_salt = memcpy (tmp + __alignof__ (uint64_t) - (uintptr_t)tmp % __alignof__ (uint64_t), salt, salt_len); assert ((uintptr_t)salt % __alignof__ (uint64_t) == 0); } struct sha512_ctx ctx; struct sha512_ctx alt_ctx; /* Prepare for the real work. */ __sha512_init_ctx (&ctx); /* Add the key string. */ __sha512_process_bytes (key, key_len, &ctx); /* The last part is the salt string. This must be at most 16 characters and it ends at the first `$' character. */ __sha512_process_bytes (salt, salt_len, &ctx); /* Compute alternate SHA512 sum with input KEY, SALT, and KEY. The final result will be added to the first context. */ __sha512_init_ctx (&alt_ctx); /* Add key. */ __sha512_process_bytes (key, key_len, &alt_ctx); /* Add salt. */ __sha512_process_bytes (salt, salt_len, &alt_ctx); /* Add key again. */ __sha512_process_bytes (key, key_len, &alt_ctx); /* Now get result of this (64 bytes) and add it to the other context. */ __sha512_finish_ctx (&alt_ctx, alt_result); /* Add for any character in the key one byte of the alternate sum. */ for (cnt = key_len; cnt > 64; cnt -= 64) __sha512_process_bytes (alt_result, 64, &ctx); __sha512_process_bytes (alt_result, cnt, &ctx); /* Take the binary representation of the length of the key and for every 1 add the alternate sum, for every 0 the key. */ for (cnt = key_len; cnt > 0; cnt >>= 1) if ((cnt & 1) != 0) __sha512_process_bytes (alt_result, 64, &ctx); else __sha512_process_bytes (key, key_len, &ctx); /* Create intermediate result. */ __sha512_finish_ctx (&ctx, alt_result); /* Start computation of P byte sequence. */ __sha512_init_ctx (&alt_ctx); /* For every character in the password add the entire password. */ for (cnt = 0; cnt < key_len; ++cnt) __sha512_process_bytes (key, key_len, &alt_ctx); /* Finish the digest. */ __sha512_finish_ctx (&alt_ctx, temp_result); /* Create byte sequence P. */ cp = p_bytes = alloca (key_len); for (cnt = key_len; cnt >= 64; cnt -= 64) cp = mempcpy (cp, temp_result, 64); memcpy (cp, temp_result, cnt); /* Start computation of S byte sequence. */ __sha512_init_ctx (&alt_ctx); /* For every character in the password add the entire password. */ for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) __sha512_process_bytes (salt, salt_len, &alt_ctx); /* Finish the digest. */ __sha512_finish_ctx (&alt_ctx, temp_result); /* Create byte sequence S. */ cp = s_bytes = alloca (salt_len); for (cnt = salt_len; cnt >= 64; cnt -= 64) cp = mempcpy (cp, temp_result, 64); memcpy (cp, temp_result, cnt); /* Repeatedly run the collected hash value through SHA512 to burn CPU cycles. */ for (cnt = 0; cnt < rounds; ++cnt) { /* New context. */ __sha512_init_ctx (&ctx); /* Add key or last result. */ if ((cnt & 1) != 0) __sha512_process_bytes (p_bytes, key_len, &ctx); else __sha512_process_bytes (alt_result, 64, &ctx); /* Add salt for numbers not divisible by 3. */ if (cnt % 3 != 0) __sha512_process_bytes (s_bytes, salt_len, &ctx); /* Add key for numbers not divisible by 7. */ if (cnt % 7 != 0) __sha512_process_bytes (p_bytes, key_len, &ctx); /* Add key or last result. */ if ((cnt & 1) != 0) __sha512_process_bytes (alt_result, 64, &ctx); else __sha512_process_bytes (p_bytes, key_len, &ctx); /* Create intermediate result. */ __sha512_finish_ctx (&ctx, alt_result); } /* Now we can construct the result string. It consists of three parts. */ cp = stpncpy (buffer, sha512_salt_prefix, MAX (0, buflen)); buflen -= sizeof (sha512_salt_prefix) - 1; if (rounds_custom) { int n = snprintf (cp, MAX (0, buflen), "%s%zu$", sha512_rounds_prefix, rounds); cp += n; buflen -= n; } cp = stpncpy (cp, salt, MIN ((size_t) MAX (0, buflen), salt_len)); buflen -= MIN ((size_t) MAX (0, buflen), salt_len); if (buflen > 0) { *cp++ = '$'; --buflen; } B64_FROM_24BIT (alt_result[0], alt_result[21], alt_result[42], 4); B64_FROM_24BIT (alt_result[22], alt_result[43], alt_result[1], 4); B64_FROM_24BIT (alt_result[44], alt_result[2], alt_result[23], 4); B64_FROM_24BIT (alt_result[3], alt_result[24], alt_result[45], 4); B64_FROM_24BIT (alt_result[25], alt_result[46], alt_result[4], 4); B64_FROM_24BIT (alt_result[47], alt_result[5], alt_result[26], 4); B64_FROM_24BIT (alt_result[6], alt_result[27], alt_result[48], 4); B64_FROM_24BIT (alt_result[28], alt_result[49], alt_result[7], 4); B64_FROM_24BIT (alt_result[50], alt_result[8], alt_result[29], 4); B64_FROM_24BIT (alt_result[9], alt_result[30], alt_result[51], 4); B64_FROM_24BIT (alt_result[31], alt_result[52], alt_result[10], 4); B64_FROM_24BIT (alt_result[53], alt_result[11], alt_result[32], 4); B64_FROM_24BIT (alt_result[12], alt_result[33], alt_result[54], 4); B64_FROM_24BIT (alt_result[34], alt_result[55], alt_result[13], 4); B64_FROM_24BIT (alt_result[56], alt_result[14], alt_result[35], 4); B64_FROM_24BIT (alt_result[15], alt_result[36], alt_result[57], 4); B64_FROM_24BIT (alt_result[37], alt_result[58], alt_result[16], 4); B64_FROM_24BIT (alt_result[59], alt_result[17], alt_result[38], 4); B64_FROM_24BIT (alt_result[18], alt_result[39], alt_result[60], 4); B64_FROM_24BIT (alt_result[40], alt_result[61], alt_result[19], 4); B64_FROM_24BIT (alt_result[62], alt_result[20], alt_result[41], 4); B64_FROM_24BIT (0, 0, alt_result[63], 2); if (buflen <= 0) { __set_errno (ERANGE); buffer = NULL; } else *cp = '\0'; /* Terminate the string. */ /* Clear the buffer for the intermediate result so that people attaching to processes or reading core dumps cannot get any information. We do it in this way to clear correct_words[] inside the SHA512 implementation as well. */ __sha512_init_ctx (&ctx); __sha512_finish_ctx (&ctx, alt_result); memset (&ctx, '\0', sizeof (ctx)); memset (&alt_ctx, '\0', sizeof (alt_ctx)); memset (temp_result, '\0', sizeof (temp_result)); memset (p_bytes, '\0', key_len); memset (s_bytes, '\0', salt_len); if (copied_key != NULL) memset (copied_key, '\0', key_len); if (copied_salt != NULL) memset (copied_salt, '\0', salt_len); return buffer; } static char *buffer; /* This entry point is equivalent to the `crypt' function in Unix libcs. */ char * __sha512_crypt (const unsigned char *key, const unsigned char *salt) { /* We don't want to have an arbitrary limit in the size of the password. We can compute an upper bound for the size of the result in advance and so we can prepare the buffer we pass to `sha512_crypt_r'. */ static int buflen; int needed = (sizeof (sha512_salt_prefix) - 1 + sizeof (sha512_rounds_prefix) + 9 + 1 + strlen (salt) + 1 + 86 + 1); if (buflen < needed) { char *new_buffer = (char *) realloc (buffer, needed); if (new_buffer == NULL) return NULL; buffer = new_buffer; buflen = needed; } return __sha512_crypt_r ((const char *) key, (const char *) salt, buffer, buflen); } |