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