1 /* $OpenBSD: bcrypt.c,v 1.25 2012/09/04 22:16:17 tedu 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 #include <stdio.h> 49 #include <stdlib.h> 50 #include <sys/types.h> 51 #include <string.h> 52 #include <pwd.h> 53 #include <blf.h> 54 55 /* This implementation is adaptable to current computing power. 56 * You can have up to 2^31 rounds which should be enough for some 57 * time to come. 58 */ 59 60 #define BCRYPT_VERSION '2' 61 #define BCRYPT_MAXSALT 16 /* Precomputation is just so nice */ 62 #define BCRYPT_BLOCKS 6 /* Ciphertext blocks */ 63 #define BCRYPT_MINROUNDS 16 /* we have log2(rounds) in salt */ 64 65 char *bcrypt_gensalt(u_int8_t); 66 67 static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t); 68 static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t); 69 static void decode_base64(u_int8_t *, u_int16_t, u_int8_t *); 70 71 static char encrypted[_PASSWORD_LEN]; 72 static char gsalt[7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1]; 73 static char error[] = ":"; 74 75 const static u_int8_t Base64Code[] = 76 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; 77 78 const static u_int8_t index_64[128] = { 79 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 80 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 81 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 82 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 83 255, 255, 255, 255, 255, 255, 0, 1, 54, 55, 84 56, 57, 58, 59, 60, 61, 62, 63, 255, 255, 85 255, 255, 255, 255, 255, 2, 3, 4, 5, 6, 86 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 87 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 88 255, 255, 255, 255, 255, 255, 28, 29, 30, 89 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 90 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 91 51, 52, 53, 255, 255, 255, 255, 255 92 }; 93 #define CHAR64(c) ( (c) > 127 ? 255 : index_64[(c)]) 94 95 static void 96 decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data) 97 { 98 u_int8_t *bp = buffer; 99 u_int8_t *p = data; 100 u_int8_t c1, c2, c3, c4; 101 while (bp < buffer + len) { 102 c1 = CHAR64(*p); 103 c2 = CHAR64(*(p + 1)); 104 105 /* Invalid data */ 106 if (c1 == 255 || c2 == 255) 107 break; 108 109 *bp++ = (c1 << 2) | ((c2 & 0x30) >> 4); 110 if (bp >= buffer + len) 111 break; 112 113 c3 = CHAR64(*(p + 2)); 114 if (c3 == 255) 115 break; 116 117 *bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2); 118 if (bp >= buffer + len) 119 break; 120 121 c4 = CHAR64(*(p + 3)); 122 if (c4 == 255) 123 break; 124 *bp++ = ((c3 & 0x03) << 6) | c4; 125 126 p += 4; 127 } 128 } 129 130 static void 131 encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr) 132 { 133 salt[0] = '$'; 134 salt[1] = BCRYPT_VERSION; 135 salt[2] = 'a'; 136 salt[3] = '$'; 137 138 snprintf(salt + 4, 4, "%2.2u$", logr); 139 140 encode_base64((u_int8_t *) salt + 7, csalt, clen); 141 } 142 /* Generates a salt for this version of crypt. 143 Since versions may change. Keeping this here 144 seems sensible. 145 */ 146 147 char * 148 bcrypt_gensalt(u_int8_t log_rounds) 149 { 150 u_int8_t csalt[BCRYPT_MAXSALT]; 151 152 arc4random_buf(csalt, sizeof(csalt)); 153 154 if (log_rounds < 4) 155 log_rounds = 4; 156 else if (log_rounds > 31) 157 log_rounds = 31; 158 159 encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds); 160 return gsalt; 161 } 162 /* We handle $Vers$log2(NumRounds)$salt+passwd$ 163 i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */ 164 165 char * 166 bcrypt(const char *key, const char *salt) 167 { 168 blf_ctx state; 169 u_int32_t rounds, i, k; 170 u_int16_t j; 171 u_int8_t key_len, salt_len, logr, minor; 172 u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt"; 173 u_int8_t csalt[BCRYPT_MAXSALT]; 174 u_int32_t cdata[BCRYPT_BLOCKS]; 175 int n; 176 177 /* Discard "$" identifier */ 178 salt++; 179 180 if (*salt > BCRYPT_VERSION) { 181 /* How do I handle errors ? Return ':' */ 182 return error; 183 } 184 185 /* Check for minor versions */ 186 if (salt[1] != '$') { 187 switch (salt[1]) { 188 case 'a': 189 /* 'ab' should not yield the same as 'abab' */ 190 minor = salt[1]; 191 salt++; 192 break; 193 default: 194 return error; 195 } 196 } else 197 minor = 0; 198 199 /* Discard version + "$" identifier */ 200 salt += 2; 201 202 if (salt[2] != '$') 203 /* Out of sync with passwd entry */ 204 return error; 205 206 /* Computer power doesn't increase linear, 2^x should be fine */ 207 n = atoi(salt); 208 if (n > 31 || n < 0) 209 return error; 210 logr = (u_int8_t)n; 211 if ((rounds = (u_int32_t) 1 << logr) < BCRYPT_MINROUNDS) 212 return error; 213 214 /* Discard num rounds + "$" identifier */ 215 salt += 3; 216 217 if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT) 218 return error; 219 220 /* We dont want the base64 salt but the raw data */ 221 decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt); 222 salt_len = BCRYPT_MAXSALT; 223 key_len = strlen(key) + (minor >= 'a' ? 1 : 0); 224 225 /* Setting up S-Boxes and Subkeys */ 226 Blowfish_initstate(&state); 227 Blowfish_expandstate(&state, csalt, salt_len, 228 (u_int8_t *) key, key_len); 229 for (k = 0; k < rounds; k++) { 230 Blowfish_expand0state(&state, (u_int8_t *) key, key_len); 231 Blowfish_expand0state(&state, csalt, salt_len); 232 } 233 234 /* This can be precomputed later */ 235 j = 0; 236 for (i = 0; i < BCRYPT_BLOCKS; i++) 237 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j); 238 239 /* Now do the encryption */ 240 for (k = 0; k < 64; k++) 241 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2); 242 243 for (i = 0; i < BCRYPT_BLOCKS; i++) { 244 ciphertext[4 * i + 3] = cdata[i] & 0xff; 245 cdata[i] = cdata[i] >> 8; 246 ciphertext[4 * i + 2] = cdata[i] & 0xff; 247 cdata[i] = cdata[i] >> 8; 248 ciphertext[4 * i + 1] = cdata[i] & 0xff; 249 cdata[i] = cdata[i] >> 8; 250 ciphertext[4 * i + 0] = cdata[i] & 0xff; 251 } 252 253 254 i = 0; 255 encrypted[i++] = '$'; 256 encrypted[i++] = BCRYPT_VERSION; 257 if (minor) 258 encrypted[i++] = minor; 259 encrypted[i++] = '$'; 260 261 snprintf(encrypted + i, 4, "%2.2u$", logr); 262 263 encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT); 264 encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext, 265 4 * BCRYPT_BLOCKS - 1); 266 memset(&state, 0, sizeof(state)); 267 memset(ciphertext, 0, sizeof(ciphertext)); 268 memset(csalt, 0, sizeof(csalt)); 269 memset(cdata, 0, sizeof(cdata)); 270 return encrypted; 271 } 272 273 static void 274 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len) 275 { 276 u_int8_t *bp = buffer; 277 u_int8_t *p = data; 278 u_int8_t c1, c2; 279 while (p < data + len) { 280 c1 = *p++; 281 *bp++ = Base64Code[(c1 >> 2)]; 282 c1 = (c1 & 0x03) << 4; 283 if (p >= data + len) { 284 *bp++ = Base64Code[c1]; 285 break; 286 } 287 c2 = *p++; 288 c1 |= (c2 >> 4) & 0x0f; 289 *bp++ = Base64Code[c1]; 290 c1 = (c2 & 0x0f) << 2; 291 if (p >= data + len) { 292 *bp++ = Base64Code[c1]; 293 break; 294 } 295 c2 = *p++; 296 c1 |= (c2 >> 6) & 0x03; 297 *bp++ = Base64Code[c1]; 298 *bp++ = Base64Code[c2 & 0x3f]; 299 } 300 *bp = '\0'; 301 } 302 #if 0 303 void 304 main() 305 { 306 char blubber[73]; 307 char salt[100]; 308 char *p; 309 salt[0] = '$'; 310 salt[1] = BCRYPT_VERSION; 311 salt[2] = '$'; 312 313 snprintf(salt + 3, 4, "%2.2u$", 5); 314 315 printf("24 bytes of salt: "); 316 fgets(salt + 6, sizeof(salt) - 6, stdin); 317 salt[99] = 0; 318 printf("72 bytes of password: "); 319 fpurge(stdin); 320 fgets(blubber, sizeof(blubber), stdin); 321 blubber[72] = 0; 322 323 p = crypt(blubber, salt); 324 printf("Passwd entry: %s\n\n", p); 325 326 p = bcrypt_gensalt(5); 327 printf("Generated salt: %s\n", p); 328 p = crypt(blubber, p); 329 printf("Passwd entry: %s\n", p); 330 } 331 #endif 332