lib/libcrypt/bcrypt.c

   1 /*      $NetBSD: bcrypt.c,v 1.8 2006/10/24 22:49:19 mlelstv Exp $       */
   2 /*      $OpenBSD: bcrypt.c,v 1.16 2002/02/19 19:39:36 millert Exp $     */
   3
   4 /*
   5  * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by Niels Provos.
  19  * 4. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /* This password hashing algorithm was designed by David Mazieres
  35  * <dm@lcs.mit.edu> and works as follows:
  36  *
  37  * 1. state := InitState ()
  38  * 2. state := ExpandKey (state, salt, password) 3.
  39  * REPEAT rounds:
  40  *      state := ExpandKey (state, 0, salt)
  41  *      state := ExpandKey(state, 0, password)
  42  * 4. ctext := "OrpheanBeholderScryDoubt"
  43  * 5. REPEAT 64:
  44  *      ctext := Encrypt_ECB (state, ctext);
  45  * 6. RETURN Concatenate (salt, ctext);
  46  *
  47  */
  48 #include <sys/cdefs.h>
  49 __RCSID("$NetBSD: bcrypt.c,v 1.8 2006/10/24 22:49:19 mlelstv Exp $");
  50
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <sys/types.h>
  54 #include <string.h>
  55 #include <pwd.h>
  56 #include <errno.h>
  57 #include <limits.h>
  58
  59 #include "crypt.h"
  60 #include "blowfish.c"
  61
  62 /* This implementation is adaptable to current computing power.
  63  * You can have up to 2^31 rounds which should be enough for some
  64  * time to come.
  65  */
  66
  67 #define BCRYPT_VERSION '2'
  68 #define BCRYPT_MAXSALT 16       /* Precomputation is just so nice */
  69 #define BCRYPT_MAXSALTLEN       (BCRYPT_MAXSALT * 4 / 3 + 1)
  70 #define BCRYPT_BLOCKS 6         /* Ciphertext blocks */
  71 #define BCRYPT_MINROUNDS 16     /* we have log2(rounds) in salt */
  72
  73 static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t);
  74 static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
  75 static void decode_base64(u_int8_t *, u_int16_t, const u_int8_t *);
  76
  77 char *__bcrypt(const char *, const char *);     /* XXX */
  78
  79 static char    encrypted[_PASSWORD_LEN];
  80 static char    error[] = ":";
  81
  82 static const u_int8_t Base64Code[] =
  83 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  84
  85 char *bcrypt_gensalt(u_int8_t);
  86
  87 static const u_int8_t index_64[128] =
  88 {
  89         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  90         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  91         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  92         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  93         255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
  94         56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
  95         255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
  96         7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
  97         17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  98         255, 255, 255, 255, 255, 255, 28, 29, 30,
  99         31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
 100         41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
 101         51, 52, 53, 255, 255, 255, 255, 255
 102 };
 103 #define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
 104
 105 static void
 106 decode_base64(u_int8_t *buffer, u_int16_t len, const u_int8_t *data)
 107 {
 108         u_int8_t *bp = buffer;
 109         const u_int8_t *p = data;
 110         u_int8_t c1, c2, c3, c4;
 111         while (bp < buffer + len) {
 112                 c1 = CHAR64(*p);
 113                 c2 = CHAR64(*(p + 1));
 114
 115                 /* Invalid data */
 116                 if (c1 == 255 || c2 == 255)
 117                         break;
 118
 119                 *bp++ = ((u_int32_t)c1 << 2) | (((u_int32_t)c2 & 0x30) >> 4);
 120                 if (bp >= buffer + len)
 121                         break;
 122
 123                 c3 = CHAR64(*(p + 2));
 124                 if (c3 == 255)
 125                         break;
 126
 127                 *bp++ = (((u_int32_t)c2 & 0x0f) << 4) | (((uint32_t)c3 & 0x3c) >> 2);
 128                 if (bp >= buffer + len)
 129                         break;
 130
 131                 c4 = CHAR64(*(p + 3));
 132                 if (c4 == 255)
 133                         break;
 134                 *bp++ = ((c3 & 0x03) << 6) | c4;
 135
 136                 p += 4;
 137         }
 138 }
 139
 140 static void
 141 encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
 142 {
 143         salt[0] = '$';
 144         salt[1] = BCRYPT_VERSION;
 145         salt[2] = 'a';
 146         salt[3] = '$';
 147
 148         snprintf(salt + 4, 4, "%2.2u$", logr);
 149
 150         encode_base64((u_int8_t *) salt + 7, csalt, clen);
 151 }
 152
 153 int
 154 __gensalt_blowfish(char *salt, size_t saltlen, const char *option)
 155 {
 156         size_t i;
 157         u_int32_t seed = 0;
 158         u_int8_t csalt[BCRYPT_MAXSALT];
 159         unsigned long nrounds;
 160         char *ep;
 161
 162         if (saltlen < BCRYPT_MAXSALTLEN) {
 163                 errno = ENOSPC;
 164                 return -1;
 165         }
 166         if (option == NULL) {
 167                 errno = EINVAL;
 168                 return -1;
 169         }
 170         nrounds = strtoul(option, &ep, 0);
 171         if (option == ep || *ep) {
 172                 errno = EINVAL;
 173                 return -1;
 174         }
 175         if (errno == ERANGE && nrounds == ULONG_MAX)
 176                 return -1;
 177
 178         if (nrounds > 255) {
 179                 errno = EINVAL;
 180                 return -1;
 181         }
 182
 183         if (nrounds < 4)
 184                 nrounds = 4;
 185
 186         for (i = 0; i < BCRYPT_MAXSALT; i++) {
 187                 if (i % 4 == 0)
 188                         seed = arc4random();
 189                 csalt[i] = seed & 0xff;
 190                 seed = seed >> 8;
 191         }
 192         encode_salt(salt, csalt, BCRYPT_MAXSALT, (u_int8_t)nrounds);
 193         return 0;
 194 }
 195
 196 /* Generates a salt for this version of crypt.
 197    Since versions may change. Keeping this here
 198    seems sensible.
 199    XXX: compat.
 200  */
 201 char *
 202 bcrypt_gensalt(u_int8_t log_rounds)
 203 {
 204         static char gsalt[BCRYPT_MAXSALTLEN];
 205         char num[10];
 206
 207         (void)snprintf(num, sizeof(num), "%d", log_rounds);
 208         if (__gensalt_blowfish(gsalt, sizeof(gsalt), num) == -1)
 209                 return NULL;
 210         return gsalt;
 211 }
 212
 213 /* We handle $Vers$log2(NumRounds)$salt+passwd$
 214    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
 215
 216 char   *
 217 __bcrypt(key, salt)
 218         const char   *key;
 219         const char   *salt;
 220 {
 221         blf_ctx state;
 222         u_int32_t rounds, i, k;
 223         u_int16_t j;
 224         u_int8_t key_len, salt_len, logr, minor;
 225         u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
 226         u_int8_t csalt[BCRYPT_MAXSALT];
 227         u_int32_t cdata[BCRYPT_BLOCKS];
 228
 229         /* Discard "$" identifier */
 230         salt++;
 231
 232         if (*salt > BCRYPT_VERSION) {
 233                 /* How do I handle errors ? Return ':' */
 234                 return error;
 235         }
 236
 237         /* Check for minor versions */
 238         if (salt[1] != '$') {
 239                  switch (salt[1]) {
 240                  case 'a':
 241                          /* 'ab' should not yield the same as 'abab' */
 242                          minor = salt[1];
 243                          salt++;
 244                          break;
 245                  default:
 246                          return error;
 247                  }
 248         } else
 249                  minor = 0;
 250
 251         /* Discard version + "$" identifier */
 252         salt += 2;
 253
 254         if (salt[2] != '$')
 255                 /* Out of sync with passwd entry */
 256                 return error;
 257
 258         /* Computer power doesn't increase linear, 2^x should be fine */
 259         if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
 260                 return error;
 261
 262         /* Discard num rounds + "$" identifier */
 263         salt += 3;
 264
 265         if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
 266                 return error;
 267
 268         /* We dont want the base64 salt but the raw data */
 269         decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *)salt);
 270         salt_len = BCRYPT_MAXSALT;
 271         key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
 272
 273         /* Setting up S-Boxes and Subkeys */
 274         Blowfish_initstate(&state);
 275         Blowfish_expandstate(&state, csalt, salt_len,
 276             (const u_int8_t *) key, key_len);
 277         for (k = 0; k < rounds; k++) {
 278                 Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
 279                 Blowfish_expand0state(&state, csalt, salt_len);
 280         }
 281
 282         /* This can be precomputed later */
 283         j = 0;
 284         for (i = 0; i < BCRYPT_BLOCKS; i++)
 285                 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
 286
 287         /* Now do the encryption */
 288         for (k = 0; k < 64; k++)
 289                 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
 290
 291         for (i = 0; i < BCRYPT_BLOCKS; i++) {
 292                 ciphertext[4 * i + 3] = cdata[i] & 0xff;
 293                 cdata[i] = cdata[i] >> 8;
 294                 ciphertext[4 * i + 2] = cdata[i] & 0xff;
 295                 cdata[i] = cdata[i] >> 8;
 296                 ciphertext[4 * i + 1] = cdata[i] & 0xff;
 297                 cdata[i] = cdata[i] >> 8;
 298                 ciphertext[4 * i + 0] = cdata[i] & 0xff;
 299         }
 300
 301
 302         i = 0;
 303         encrypted[i++] = '$';
 304         encrypted[i++] = BCRYPT_VERSION;
 305         if (minor)
 306                 encrypted[i++] = minor;
 307         encrypted[i++] = '$';
 308
 309         snprintf(encrypted + i, 4, "%2.2u$", logr);
 310
 311         encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
 312         encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
 313             4 * BCRYPT_BLOCKS - 1);
 314         return encrypted;
 315 }
 316
 317 static void
 318 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
 319 {
 320         u_int8_t *bp = buffer;
 321         u_int8_t *p = data;
 322         u_int8_t c1, c2;
 323         while (p < data + len) {
 324                 c1 = *p++;
 325                 *bp++ = Base64Code[((u_int32_t)c1 >> 2)];
 326                 c1 = (c1 & 0x03) << 4;
 327                 if (p >= data + len) {
 328                         *bp++ = Base64Code[c1];
 329                         break;
 330                 }
 331                 c2 = *p++;
 332                 c1 |= ((u_int32_t)c2 >> 4) & 0x0f;
 333                 *bp++ = Base64Code[c1];
 334                 c1 = (c2 & 0x0f) << 2;
 335                 if (p >= data + len) {
 336                         *bp++ = Base64Code[c1];
 337                         break;
 338                 }
 339                 c2 = *p++;
 340                 c1 |= ((u_int32_t)c2 >> 6) & 0x03;
 341                 *bp++ = Base64Code[c1];
 342                 *bp++ = Base64Code[c2 & 0x3f];
 343         }
 344         *bp = '\0';
 345 }
 346 #if 0
 347 void
 348 main()
 349 {
 350         char    blubber[73];
 351         char    salt[100];
 352         char   *p;
 353         salt[0] = '$';
 354         salt[1] = BCRYPT_VERSION;
 355         salt[2] = '$';
 356
 357         snprintf(salt + 3, 4, "%2.2u$", 5);
 358
 359         printf("24 bytes of salt: ");
 360         fgets(salt + 6, 94, stdin);
 361         salt[99] = 0;
 362         printf("72 bytes of password: ");
 363         fpurge(stdin);
 364         fgets(blubber, 73, stdin);
 365         blubber[72] = 0;
 366
 367         p = crypt(blubber, salt);
 368         printf("Passwd entry: %s\n\n", p);
 369
 370         p = bcrypt_gensalt(5);
 371         printf("Generated salt: %s\n", p);
 372         p = crypt(blubber, p);
 373         printf("Passwd entry: %s\n", p);
 374 }
 375 #endif