lib/libcrypt/bcrypt.c

   1 /*      $NetBSD: bcrypt.c,v 1.19 2013/08/28 17:47:07 riastradh 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 1.19 2013/08/28 17:47:07 riastradh 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       (7 + (BCRYPT_MAXSALT * 4 + 2) / 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
  81 static const u_int8_t Base64Code[] =
  82 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  83
  84 char *bcrypt_gensalt(u_int8_t);
  85
  86 static const u_int8_t index_64[128] =
  87 {
  88         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  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, 0, 1, 54, 55,
  93         56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
  94         255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
  95         7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
  96         17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  97         255, 255, 255, 255, 255, 255, 28, 29, 30,
  98         31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  99         41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
 100         51, 52, 53, 255, 255, 255, 255, 255
 101 };
 102 #define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
 103
 104 static void
 105 decode_base64(u_int8_t *buffer, u_int16_t len, const u_int8_t *data)
 106 {
 107         u_int8_t *bp = buffer;
 108         const u_int8_t *p = data;
 109         u_int8_t c1, c2, c3, c4;
 110         while (bp < buffer + len) {
 111                 c1 = CHAR64(*p);
 112                 c2 = CHAR64(*(p + 1));
 113
 114                 /* Invalid data */
 115                 if (c1 == 255 || c2 == 255)
 116                         break;
 117
 118                 *bp++ = ((u_int32_t)c1 << 2) | (((u_int32_t)c2 & 0x30) >> 4);
 119                 if (bp >= buffer + len)
 120                         break;
 121
 122                 c3 = CHAR64(*(p + 2));
 123                 if (c3 == 255)
 124                         break;
 125
 126                 *bp++ = (((u_int32_t)c2 & 0x0f) << 4) | (((uint32_t)c3 & 0x3c) >> 2);
 127                 if (bp >= buffer + len)
 128                         break;
 129
 130                 c4 = CHAR64(*(p + 3));
 131                 if (c4 == 255)
 132                         break;
 133                 *bp++ = ((c3 & 0x03) << 6) | c4;
 134
 135                 p += 4;
 136         }
 137 }
 138
 139 static void
 140 encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
 141 {
 142         salt[0] = '$';
 143         salt[1] = BCRYPT_VERSION;
 144         salt[2] = 'a';
 145         salt[3] = '$';
 146
 147         snprintf(salt + 4, 4, "%2.2u$", logr);
 148
 149         encode_base64((u_int8_t *) salt + 7, csalt, clen);
 150 }
 151
 152 int
 153 __gensalt_blowfish(char *salt, size_t saltlen, const char *option)
 154 {
 155         size_t i;
 156         u_int32_t seed = 0;
 157         u_int8_t csalt[BCRYPT_MAXSALT];
 158         unsigned long nrounds;
 159         char *ep;
 160
 161         if (saltlen < BCRYPT_MAXSALTLEN) {
 162                 errno = ENOSPC;
 163                 return -1;
 164         }
 165         if (option == NULL) {
 166                 errno = EINVAL;
 167                 return -1;
 168         }
 169         nrounds = strtoul(option, &ep, 0);
 170         if (option == ep || *ep) {
 171                 errno = EINVAL;
 172                 return -1;
 173         }
 174         if (errno == ERANGE && nrounds == ULONG_MAX)
 175                 return -1;
 176
 177         if (nrounds < 4)
 178                 nrounds = 4;
 179         else if (nrounds > 31)
 180                 nrounds = 31;
 181
 182         for (i = 0; i < BCRYPT_MAXSALT; i++) {
 183                 if (i % 4 == 0)
 184                         seed = arc4random();
 185                 csalt[i] = seed & 0xff;
 186                 seed = seed >> 8;
 187         }
 188         encode_salt(salt, csalt, BCRYPT_MAXSALT, (u_int8_t)nrounds);
 189         return 0;
 190 }
 191
 192 /* Generates a salt for this version of crypt.
 193    Since versions may change. Keeping this here
 194    seems sensible.
 195    XXX: compat.
 196  */
 197 char *
 198 bcrypt_gensalt(u_int8_t log_rounds)
 199 {
 200         static char gsalt[BCRYPT_MAXSALTLEN];
 201         char num[10];
 202
 203         (void)snprintf(num, sizeof(num), "%d", log_rounds);
 204         if (__gensalt_blowfish(gsalt, sizeof(gsalt), num) == -1)
 205                 return NULL;
 206         return gsalt;
 207 }
 208
 209 /* We handle $Vers$log2(NumRounds)$salt+passwd$
 210    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
 211
 212 char   *
 213 __bcrypt(const char *key, const char *salt)
 214 {
 215         blf_ctx state;
 216         u_int32_t rounds, i, k;
 217         u_int16_t j;
 218         u_int8_t key_len, salt_len, logr, minor;
 219         u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
 220         u_int8_t csalt[BCRYPT_MAXSALT];
 221         u_int32_t cdata[BCRYPT_BLOCKS];
 222         int n;
 223         size_t len;
 224
 225         /* Discard "$" identifier */
 226         salt++;
 227
 228         if (*salt > BCRYPT_VERSION)
 229                 return NULL;
 230
 231         /* Check for minor versions */
 232         if (salt[1] != '$') {
 233                 switch (salt[1]) {
 234                 case 'a':
 235                         /* 'ab' should not yield the same as 'abab' */
 236                         minor = salt[1];
 237                         salt++;
 238                         break;
 239                 default:
 240                         return NULL;
 241                 }
 242         } else
 243                  minor = 0;
 244
 245         /* Discard version + "$" identifier */
 246         salt += 2;
 247
 248         if (salt[2] != '$')
 249                 /* Out of sync with passwd entry */
 250                 return NULL;
 251
 252         /* Computer power doesn't increase linear, 2^x should be fine */
 253         n = atoi(salt);
 254         if (n > 31 || n < 0)
 255                 return NULL;
 256         logr = (u_int8_t)n;
 257         if ((rounds = (u_int32_t) 1 << logr) < BCRYPT_MINROUNDS)
 258                 return NULL;
 259
 260         /* Discard num rounds + "$" identifier */
 261         salt += 3;
 262
 263         if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
 264                 return NULL;
 265
 266         /* We dont want the base64 salt but the raw data */
 267         decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *)salt);
 268         salt_len = BCRYPT_MAXSALT;
 269         len = strlen(key);
 270         if (len > 72)
 271                 key_len = 72;
 272         else
 273                 key_len = (uint8_t)len;
 274         key_len += minor >= 'a' ? 1 : 0;
 275
 276         /* Setting up S-Boxes and Subkeys */
 277         Blowfish_initstate(&state);
 278         Blowfish_expandstate(&state, csalt, salt_len,
 279             (const u_int8_t *) key, key_len);
 280         for (k = 0; k < rounds; k++) {
 281                 Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
 282                 Blowfish_expand0state(&state, csalt, salt_len);
 283         }
 284
 285         /* This can be precomputed later */
 286         j = 0;
 287         for (i = 0; i < BCRYPT_BLOCKS; i++)
 288                 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
 289
 290         /* Now do the encryption */
 291         for (k = 0; k < 64; k++)
 292                 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
 293
 294         for (i = 0; i < BCRYPT_BLOCKS; i++) {
 295                 ciphertext[4 * i + 3] = cdata[i] & 0xff;
 296                 cdata[i] = cdata[i] >> 8;
 297                 ciphertext[4 * i + 2] = cdata[i] & 0xff;
 298                 cdata[i] = cdata[i] >> 8;
 299                 ciphertext[4 * i + 1] = cdata[i] & 0xff;
 300                 cdata[i] = cdata[i] >> 8;
 301                 ciphertext[4 * i + 0] = cdata[i] & 0xff;
 302         }
 303
 304
 305         i = 0;
 306         encrypted[i++] = '$';
 307         encrypted[i++] = BCRYPT_VERSION;
 308         if (minor)
 309                 encrypted[i++] = minor;
 310         encrypted[i++] = '$';
 311
 312         snprintf(encrypted + i, 4, "%2.2u$", logr);
 313
 314         encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
 315         encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
 316             4 * BCRYPT_BLOCKS - 1);
 317         explicit_memset(&state, 0, sizeof(state));
 318         return encrypted;
 319 }
 320
 321 static void
 322 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
 323 {
 324         u_int8_t *bp = buffer;
 325         u_int8_t *p = data;
 326         u_int8_t c1, c2;
 327         while (p < data + len) {
 328                 c1 = *p++;
 329                 *bp++ = Base64Code[((u_int32_t)c1 >> 2)];
 330                 c1 = (c1 & 0x03) << 4;
 331                 if (p >= data + len) {
 332                         *bp++ = Base64Code[c1];
 333                         break;
 334                 }
 335                 c2 = *p++;
 336                 c1 |= ((u_int32_t)c2 >> 4) & 0x0f;
 337                 *bp++ = Base64Code[c1];
 338                 c1 = (c2 & 0x0f) << 2;
 339                 if (p >= data + len) {
 340                         *bp++ = Base64Code[c1];
 341                         break;
 342                 }
 343                 c2 = *p++;
 344                 c1 |= ((u_int32_t)c2 >> 6) & 0x03;
 345                 *bp++ = Base64Code[c1];
 346                 *bp++ = Base64Code[c2 & 0x3f];
 347         }
 348         *bp = '\0';
 349 }
 350 #if 0
 351 void
 352 main()
 353 {
 354         char    blubber[73];
 355         char    salt[100];
 356         char   *p;
 357         salt[0] = '$';
 358         salt[1] = BCRYPT_VERSION;
 359         salt[2] = '$';
 360
 361         snprintf(salt + 3, 4, "%2.2u$", 5);
 362
 363         printf("24 bytes of salt: ");
 364         fgets(salt + 6, 94, stdin);
 365         salt[99] = 0;
 366         printf("72 bytes of password: ");
 367         fpurge(stdin);
 368         fgets(blubber, 73, stdin);
 369         blubber[72] = 0;
 370
 371         p = crypt(blubber, salt);
 372         printf("Passwd entry: %s\n\n", p);
 373
 374         p = bcrypt_gensalt(5);
 375         printf("Generated salt: %s\n", p);
 376         p = crypt(blubber, p);
 377         printf("Passwd entry: %s\n", p);
 378 }
 379 #endif