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 #include "crypt.h"
  63
  64 /* This implementation is adaptable to current computing power.
  65  * You can have up to 2^31 rounds which should be enough for some
  66  * time to come.
  67  */
  68
  69 #define BCRYPT_VERSION '2'
  70 #define BCRYPT_MAXSALT 16       /* Precomputation is just so nice */
  71 #define BCRYPT_BLOCKS 6         /* Ciphertext blocks */
  72 #define BCRYPT_MINROUNDS 16     /* we have log2(rounds) in salt */
  73
  74 char   *bcrypt_gensalt (u_int8_t);
  75
  76 static void encode_salt (char *, u_int8_t *, u_int16_t, u_int8_t);
  77 static void encode_base64 (u_int8_t *, u_int8_t *, u_int16_t);
  78 static void decode_base64 (u_int8_t *, u_int16_t, u_int8_t *);
  79
  80 static char    encrypted[_PASSWORD_LEN];
  81 static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
  82
  83 static const u_int8_t Base64Code[] =
  84 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  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, u_int8_t *data)
 106 {
 107         u_int8_t *bp = buffer;
 108         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++ = (c1 << 2) | ((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++ = ((c2 & 0x0f) << 4) | ((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 /* Generates a salt for this version of crypt.
 152    Since versions may change. Keeping this here
 153    seems sensible.
 154  */
 155
 156 char *
 157 bcrypt_gensalt(u_int8_t log_rounds)
 158 {
 159         u_int8_t csalt[BCRYPT_MAXSALT];
 160         u_int16_t i;
 161         u_int32_t seed = 0;
 162
 163         for (i = 0; i < BCRYPT_MAXSALT; i++) {
 164                 if (i % 4 == 0)
 165                         seed = arc4random();
 166                 csalt[i] = seed & 0xff;
 167                 seed = seed >> 8;
 168         }
 169
 170         if (log_rounds < 4)
 171                 log_rounds = 4;
 172
 173         encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
 174         return gsalt;
 175 }
 176 /* We handle $Vers$log2(NumRounds)$salt+passwd$
 177    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
 178
 179 char   *
 180 crypt_blowfish(const char *key, const char *salt)
 181 {
 182         blf_ctx state;
 183         u_int32_t rounds, i, k;
 184         u_int16_t j;
 185         u_int8_t key_len, salt_len, logr, minor;
 186         u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
 187         u_int8_t csalt[BCRYPT_MAXSALT];
 188         u_int32_t cdata[BCRYPT_BLOCKS];
 189         static const char *magic = "$2a$04$";
 190
 191                 /* Defaults */
 192         minor = 'a';
 193         logr = 4;
 194         rounds = 1 << logr;
 195
 196         /* If it starts with the magic string, then skip that */
 197         if(!strncmp(salt, magic, strlen(magic))) {
 198                 salt += strlen(magic);
 199         }
 200         else if (*salt == '$') {
 201
 202                 /* Discard "$" identifier */
 203                 salt++;
 204
 205                 if (*salt > BCRYPT_VERSION) {
 206                         /* How do I handle errors ? Return NULL according to
 207                            crypt(3) */
 208                         return NULL;
 209                 }
 210
 211                 /* Check for minor versions */
 212                 if (salt[1] != '$') {
 213                          switch (salt[1]) {
 214                          case 'a':
 215                                  /* 'ab' should not yield the same as 'abab' */
 216                                  minor = salt[1];
 217                                  salt++;
 218                                  break;
 219                          default:
 220                                  return NULL;
 221                          }
 222                 } else
 223                          minor = 0;
 224
 225                 /* Discard version + "$" identifier */
 226                 salt += 2;
 227
 228                 if (salt[2] != '$')
 229                         /* Out of sync with passwd entry */
 230                         return NULL;
 231
 232                 /* Computer power doesnt increase linear, 2^x should be fine */
 233                 if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
 234                         return NULL;
 235
 236                 /* Discard num rounds + "$" identifier */
 237                 salt += 3;
 238         }
 239
 240
 241         /* We dont want the base64 salt but the raw data */
 242         decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
 243         salt_len = BCRYPT_MAXSALT;
 244         key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
 245
 246         /* Setting up S-Boxes and Subkeys */
 247         Blowfish_initstate(&state);
 248         Blowfish_expandstate(&state, csalt, salt_len,
 249             (u_int8_t *) key, key_len);
 250         for (k = 0; k < rounds; k++) {
 251                 Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
 252                 Blowfish_expand0state(&state, csalt, salt_len);
 253         }
 254
 255         /* This can be precomputed later */
 256         j = 0;
 257         for (i = 0; i < BCRYPT_BLOCKS; i++)
 258                 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
 259
 260         /* Now do the encryption */
 261         for (k = 0; k < 64; k++)
 262                 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
 263
 264         for (i = 0; i < BCRYPT_BLOCKS; i++) {
 265                 ciphertext[4 * i + 3] = cdata[i] & 0xff;
 266                 cdata[i] = cdata[i] >> 8;
 267                 ciphertext[4 * i + 2] = cdata[i] & 0xff;
 268                 cdata[i] = cdata[i] >> 8;
 269                 ciphertext[4 * i + 1] = cdata[i] & 0xff;
 270                 cdata[i] = cdata[i] >> 8;
 271                 ciphertext[4 * i + 0] = cdata[i] & 0xff;
 272         }
 273
 274
 275         i = 0;
 276         encrypted[i++] = '$';
 277         encrypted[i++] = BCRYPT_VERSION;
 278         if (minor)
 279                 encrypted[i++] = minor;
 280         encrypted[i++] = '$';
 281
 282         snprintf(encrypted + i, 4, "%2.2u$", logr);
 283
 284         encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
 285         encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
 286             4 * BCRYPT_BLOCKS - 1);
 287         return encrypted;
 288 }
 289
 290 static void
 291 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
 292 {
 293         u_int8_t *bp = buffer;
 294         u_int8_t *p = data;
 295         u_int8_t c1, c2;
 296         while (p < data + len) {
 297                 c1 = *p++;
 298                 *bp++ = Base64Code[(c1 >> 2)];
 299                 c1 = (c1 & 0x03) << 4;
 300                 if (p >= data + len) {
 301                         *bp++ = Base64Code[c1];
 302                         break;
 303                 }
 304                 c2 = *p++;
 305                 c1 |= (c2 >> 4) & 0x0f;
 306                 *bp++ = Base64Code[c1];
 307                 c1 = (c2 & 0x0f) << 2;
 308                 if (p >= data + len) {
 309                         *bp++ = Base64Code[c1];
 310                         break;
 311                 }
 312                 c2 = *p++;
 313                 c1 |= (c2 >> 6) & 0x03;
 314                 *bp++ = Base64Code[c1];
 315                 *bp++ = Base64Code[c2 & 0x3f];
 316         }
 317         *bp = '\0';
 318 }
 319 #if 0
 320 void
 321 main()
 322 {
 323         char    blubber[73];
 324         char    salt[100];
 325         char   *p;
 326         salt[0] = '$';
 327         salt[1] = BCRYPT_VERSION;
 328         salt[2] = '$';
 329
 330         snprintf(salt + 3, 4, "%2.2u$", 5);
 331
 332         printf("24 bytes of salt: ");
 333         fgets(salt + 6, 94, stdin);
 334         salt[99] = 0;
 335         printf("72 bytes of password: ");
 336         fpurge(stdin);
 337         fgets(blubber, 73, stdin);
 338         blubber[72] = 0;
 339
 340         p = crypt(blubber, salt);
 341         printf("Passwd entry: %s\n\n", p);
 342
 343         p = bcrypt_gensalt(5);
 344         printf("Generated salt: %s\n", p);
 345         p = crypt(blubber, p);
 346         printf("Passwd entry: %s\n", p);
 347 }
 348 #endif