lib/libcrypt/crypt-blowfish.c

   1 /*
   2  * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Niels Provos.
  16  * 4. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * $FreeBSD: src/secure/lib/libcrypt/crypt-blowfish.c,v 1.1.2.1 2001/05/24 12:20:03 markm Exp $
  31  */
  32
  33 /* This password hashing algorithm was designed by David Mazieres
  34  * <dm@lcs.mit.edu> and works as follows:
  35  *
  36  * 1. state := InitState ()
  37  * 2. state := ExpandKey (state, salt, password) 3.
  38  * REPEAT rounds:
  39  *      state := ExpandKey (state, 0, salt)
  40  *      state := ExpandKey(state, 0, password)
  41  * 4. ctext := "OrpheanBeholderScryDoubt"
  42  * 5. REPEAT 64:
  43  *      ctext := Encrypt_ECB (state, ctext);
  44  * 6. RETURN Concatenate (salt, ctext);
  45  *
  46  */
  47
  48 /*
  49  * FreeBSD implementation by Paul Herman <pherman@frenchfries.net>
  50  */
  51
  52 #if 0
  53 #include <stdio.h>
  54 #endif
  55
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <sys/types.h>
  59 #include <string.h>
  60 #include <pwd.h>
  61 #include "blowfish.h"
  62
  63 /* This implementation is adaptable to current computing power.
  64  * You can have up to 2^31 rounds which should be enough for some
  65  * time to come.
  66  */
  67
  68 #define BCRYPT_VERSION '2'
  69 #define BCRYPT_MAXSALT 16       /* Precomputation is just so nice */
  70 #define BCRYPT_BLOCKS 6         /* Ciphertext blocks */
  71 #define BCRYPT_MINROUNDS 16     /* we have log2(rounds) in salt */
  72
  73 char   *bcrypt_gensalt (u_int8_t);
  74
  75 static void encode_salt (char *, u_int8_t *, u_int16_t, u_int8_t);
  76 static void encode_base64 (u_int8_t *, u_int8_t *, u_int16_t);
  77 static void decode_base64 (u_int8_t *, u_int16_t, u_int8_t *);
  78
  79 static char    encrypted[_PASSWORD_LEN];
  80 static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
  81
  82 static const u_int8_t Base64Code[] =
  83 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  84
  85 static const u_int8_t index_64[128] =
  86 {
  87         255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  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, 0, 1, 54, 55,
  92         56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
  93         255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
  94         7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
  95         17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  96         255, 255, 255, 255, 255, 255, 28, 29, 30,
  97         31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  98         41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
  99         51, 52, 53, 255, 255, 255, 255, 255
 100 };
 101 #define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
 102
 103 static void
 104 decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data)
 105 {
 106         u_int8_t *bp = buffer;
 107         u_int8_t *p = data;
 108         u_int8_t c1, c2, c3, c4;
 109         while (bp < buffer + len) {
 110                 c1 = CHAR64(*p);
 111                 c2 = CHAR64(*(p + 1));
 112
 113                 /* Invalid data */
 114                 if (c1 == 255 || c2 == 255)
 115                         break;
 116
 117                 *bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
 118                 if (bp >= buffer + len)
 119                         break;
 120
 121                 c3 = CHAR64(*(p + 2));
 122                 if (c3 == 255)
 123                         break;
 124
 125                 *bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
 126                 if (bp >= buffer + len)
 127                         break;
 128
 129                 c4 = CHAR64(*(p + 3));
 130                 if (c4 == 255)
 131                         break;
 132                 *bp++ = ((c3 & 0x03) << 6) | c4;
 133
 134                 p += 4;
 135         }
 136 }
 137
 138 static void
 139 encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
 140 {
 141         salt[0] = '$';
 142         salt[1] = BCRYPT_VERSION;
 143         salt[2] = 'a';
 144         salt[3] = '$';
 145
 146         snprintf(salt + 4, 4, "%2.2u$", logr);
 147
 148         encode_base64((u_int8_t *) salt + 7, csalt, clen);
 149 }
 150 /* Generates a salt for this version of crypt.
 151    Since versions may change. Keeping this here
 152    seems sensible.
 153  */
 154
 155 char *
 156 bcrypt_gensalt(u_int8_t log_rounds)
 157 {
 158         u_int8_t csalt[BCRYPT_MAXSALT];
 159         u_int16_t i;
 160         u_int32_t seed = 0;
 161
 162         for (i = 0; i < BCRYPT_MAXSALT; i++) {
 163                 if (i % 4 == 0)
 164                         seed = arc4random();
 165                 csalt[i] = seed & 0xff;
 166                 seed = seed >> 8;
 167         }
 168
 169         if (log_rounds < 4)
 170                 log_rounds = 4;
 171
 172         encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
 173         return gsalt;
 174 }
 175 /* We handle $Vers$log2(NumRounds)$salt+passwd$
 176    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
 177
 178 char   *
 179 crypt_blowfish(const char *key, const char *salt)
 180 {
 181         blf_ctx state;
 182         u_int32_t rounds, i, k;
 183         u_int16_t j;
 184         u_int8_t key_len, salt_len, logr, minor;
 185         u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
 186         u_int8_t csalt[BCRYPT_MAXSALT];
 187         u_int32_t cdata[BCRYPT_BLOCKS];
 188         static char     *magic = "$2a$04$";
 189
 190                 /* Defaults */
 191         minor = 'a';
 192         logr = 4;
 193         rounds = 1 << logr;
 194
 195         /* If it starts with the magic string, then skip that */
 196         if(!strncmp(salt, magic, strlen(magic))) {
 197                 salt += strlen(magic);
 198         }
 199         else if (*salt == '$') {
 200
 201                 /* Discard "$" identifier */
 202                 salt++;
 203
 204                 if (*salt > BCRYPT_VERSION) {
 205                         /* How do I handle errors ? Return NULL according to
 206                            crypt(3) */
 207                         return NULL;
 208                 }
 209
 210                 /* Check for minor versions */
 211                 if (salt[1] != '$') {
 212                          switch (salt[1]) {
 213                          case 'a':
 214                                  /* 'ab' should not yield the same as 'abab' */
 215                                  minor = salt[1];
 216                                  salt++;
 217                                  break;
 218                          default:
 219                                  return NULL;
 220                          }
 221                 } else
 222                          minor = 0;
 223
 224                 /* Discard version + "$" identifier */
 225                 salt += 2;
 226
 227                 if (salt[2] != '$')
 228                         /* Out of sync with passwd entry */
 229                         return NULL;
 230
 231                 /* Computer power doesnt increase linear, 2^x should be fine */
 232                 if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
 233                         return NULL;
 234
 235                 /* Discard num rounds + "$" identifier */
 236                 salt += 3;
 237         }
 238
 239
 240         /* We dont want the base64 salt but the raw data */
 241         decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
 242         salt_len = BCRYPT_MAXSALT;
 243         key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
 244
 245         /* Setting up S-Boxes and Subkeys */
 246         Blowfish_initstate(&state);
 247         Blowfish_expandstate(&state, csalt, salt_len,
 248             (u_int8_t *) key, key_len);
 249         for (k = 0; k < rounds; k++) {
 250                 Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
 251                 Blowfish_expand0state(&state, csalt, salt_len);
 252         }
 253
 254         /* This can be precomputed later */
 255         j = 0;
 256         for (i = 0; i < BCRYPT_BLOCKS; i++)
 257                 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
 258
 259         /* Now do the encryption */
 260         for (k = 0; k < 64; k++)
 261                 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
 262
 263         for (i = 0; i < BCRYPT_BLOCKS; i++) {
 264                 ciphertext[4 * i + 3] = cdata[i] & 0xff;
 265                 cdata[i] = cdata[i] >> 8;
 266                 ciphertext[4 * i + 2] = cdata[i] & 0xff;
 267                 cdata[i] = cdata[i] >> 8;
 268                 ciphertext[4 * i + 1] = cdata[i] & 0xff;
 269                 cdata[i] = cdata[i] >> 8;
 270                 ciphertext[4 * i + 0] = cdata[i] & 0xff;
 271         }
 272
 273
 274         i = 0;
 275         encrypted[i++] = '$';
 276         encrypted[i++] = BCRYPT_VERSION;
 277         if (minor)
 278                 encrypted[i++] = minor;
 279         encrypted[i++] = '$';
 280
 281         snprintf(encrypted + i, 4, "%2.2u$", logr);
 282
 283         encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
 284         encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
 285             4 * BCRYPT_BLOCKS - 1);
 286         return encrypted;
 287 }
 288
 289 static void
 290 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
 291 {
 292         u_int8_t *bp = buffer;
 293         u_int8_t *p = data;
 294         u_int8_t c1, c2;
 295         while (p < data + len) {
 296                 c1 = *p++;
 297                 *bp++ = Base64Code[(c1 >> 2)];
 298                 c1 = (c1 & 0x03) << 4;
 299                 if (p >= data + len) {
 300                         *bp++ = Base64Code[c1];
 301                         break;
 302                 }
 303                 c2 = *p++;
 304                 c1 |= (c2 >> 4) & 0x0f;
 305                 *bp++ = Base64Code[c1];
 306                 c1 = (c2 & 0x0f) << 2;
 307                 if (p >= data + len) {
 308                         *bp++ = Base64Code[c1];
 309                         break;
 310                 }
 311                 c2 = *p++;
 312                 c1 |= (c2 >> 6) & 0x03;
 313                 *bp++ = Base64Code[c1];
 314                 *bp++ = Base64Code[c2 & 0x3f];
 315         }
 316         *bp = '\0';
 317 }
 318 #if 0
 319 void
 320 main()
 321 {
 322         char    blubber[73];
 323         char    salt[100];
 324         char   *p;
 325         salt[0] = '$';
 326         salt[1] = BCRYPT_VERSION;
 327         salt[2] = '$';
 328
 329         snprintf(salt + 3, 4, "%2.2u$", 5);
 330
 331         printf("24 bytes of salt: ");
 332         fgets(salt + 6, 94, stdin);
 333         salt[99] = 0;
 334         printf("72 bytes of password: ");
 335         fpurge(stdin);
 336         fgets(blubber, 73, stdin);
 337         blubber[72] = 0;
 338
 339         p = crypt(blubber, salt);
 340         printf("Passwd entry: %s\n\n", p);
 341
 342         p = bcrypt_gensalt(5);
 343         printf("Generated salt: %s\n", p);
 344         p = crypt(blubber, p);
 345         printf("Passwd entry: %s\n", p);
 346 }
 347 #endif