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bcrypt.c revision 1.3 
      1 /*	$NetBSD: bcrypt.c,v 1.3 2003/08/06 08:34:32 jdolecek Exp $	*/
      2 /*	$OpenBSD: bcrypt.c,v 1.16 2002/02/19 19:39:36 millert Exp $	*/
      3 
      4 /*
      5  * Copyright 1997 Niels Provos <provos (at) 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 (at) 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 
     49 #if 0
     50 #include <stdio.h>
     51 #endif
     52 
     53 #include <sys/cdefs.h>
     54 __RCSID("$NetBSD: bcrypt.c,v 1.3 2003/08/06 08:34:32 jdolecek Exp $");
     55 
     56 #include <stdio.h>
     57 #include <stdlib.h>
     58 #include <sys/types.h>
     59 #include <string.h>
     60 #include <pwd.h>
     61 
     62 #include "blowfish.c"
     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 static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t);
     75 static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
     76 static void decode_base64(u_int8_t *, u_int16_t, u_int8_t *);
     77 
     78 char *__bcrypt(const char *, const char *);	/* XXX */
     79 
     80 static char    encrypted[_PASSWORD_LEN];
     81 static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
     82 static char    error[] = ":";
     83 
     84 const static u_int8_t Base64Code[] =
     85 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
     86 
     87 const static u_int8_t index_64[128] =
     88 {
     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, 255, 255, 255, 255,
     93 	255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
     94 	56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
     95 	255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
     96 	7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
     97 	17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
     98 	255, 255, 255, 255, 255, 255, 28, 29, 30,
     99 	31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    100 	41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
    101 	51, 52, 53, 255, 255, 255, 255, 255
    102 };
    103 #define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
    104 
    105 static void
    106 decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data)
    107 {
    108 	u_int8_t *bp = buffer;
    109 	u_int8_t *p = data;
    110 	u_int8_t c1, c2, c3, c4;
    111 	while (bp < buffer + len) {
    112 		c1 = CHAR64(*p);
    113 		c2 = CHAR64(*(p + 1));
    114 
    115 		/* Invalid data */
    116 		if (c1 == 255 || c2 == 255)
    117 			break;
    118 
    119 		*bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
    120 		if (bp >= buffer + len)
    121 			break;
    122 
    123 		c3 = CHAR64(*(p + 2));
    124 		if (c3 == 255)
    125 			break;
    126 
    127 		*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
    128 		if (bp >= buffer + len)
    129 			break;
    130 
    131 		c4 = CHAR64(*(p + 3));
    132 		if (c4 == 255)
    133 			break;
    134 		*bp++ = ((c3 & 0x03) << 6) | c4;
    135 
    136 		p += 4;
    137 	}
    138 }
    139 
    140 static void
    141 encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
    142 {
    143 	salt[0] = '$';
    144 	salt[1] = BCRYPT_VERSION;
    145 	salt[2] = 'a';
    146 	salt[3] = '$';
    147 
    148 	snprintf(salt + 4, 4, "%2.2u$", logr);
    149 
    150 	encode_base64((u_int8_t *) salt + 7, csalt, clen);
    151 }
    152 
    153 /* Generates a salt for this version of crypt.
    154    Since versions may change. Keeping this here
    155    seems sensible.
    156  */
    157 char *
    158 bcrypt_gensalt(u_int8_t log_rounds)
    159 {
    160 	u_int8_t csalt[BCRYPT_MAXSALT];
    161 	u_int16_t i;
    162 	u_int32_t seed = 0;
    163 
    164 	for (i = 0; i < BCRYPT_MAXSALT; i++) {
    165 		if (i % 4 == 0)
    166 			seed = arc4random();
    167 		csalt[i] = seed & 0xff;
    168 		seed = seed >> 8;
    169 	}
    170 
    171 	if (log_rounds < 4)
    172 		log_rounds = 4;
    173 
    174 	encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
    175 	return gsalt;
    176 }
    177 
    178 /* We handle $Vers$log2(NumRounds)$salt+passwd$
    179    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
    180 
    181 char   *
    182 __bcrypt(key, salt)
    183 	const char   *key;
    184 	const char   *salt;
    185 {
    186 	blf_ctx state;
    187 	u_int32_t rounds, i, k;
    188 	u_int16_t j;
    189 	u_int8_t key_len, salt_len, logr, minor;
    190 	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
    191 	u_int8_t csalt[BCRYPT_MAXSALT];
    192 	u_int32_t cdata[BCRYPT_BLOCKS];
    193 
    194 	/* Discard "$" identifier */
    195 	salt++;
    196 
    197 	if (*salt > BCRYPT_VERSION) {
    198 		/* How do I handle errors ? Return ':' */
    199 		return error;
    200 	}
    201 
    202 	/* Check for minor versions */
    203 	if (salt[1] != '$') {
    204 		 switch (salt[1]) {
    205 		 case 'a':
    206 			 /* 'ab' should not yield the same as 'abab' */
    207 			 minor = salt[1];
    208 			 salt++;
    209 			 break;
    210 		 default:
    211 			 return error;
    212 		 }
    213 	} else
    214 		 minor = 0;
    215 
    216 	/* Discard version + "$" identifier */
    217 	salt += 2;
    218 
    219 	if (salt[2] != '$')
    220 		/* Out of sync with passwd entry */
    221 		return error;
    222 
    223 	/* Computer power doesn't increase linear, 2^x should be fine */
    224 	if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
    225 		return error;
    226 
    227 	/* Discard num rounds + "$" identifier */
    228 	salt += 3;
    229 
    230 	if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
    231 		return error;
    232 
    233 	/* We dont want the base64 salt but the raw data */
    234 	decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
    235 	salt_len = BCRYPT_MAXSALT;
    236 	key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
    237 
    238 	/* Setting up S-Boxes and Subkeys */
    239 	Blowfish_initstate(&state);
    240 	Blowfish_expandstate(&state, csalt, salt_len,
    241 	    (u_int8_t *) key, key_len);
    242 	for (k = 0; k < rounds; k++) {
    243 		Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
    244 		Blowfish_expand0state(&state, csalt, salt_len);
    245 	}
    246 
    247 	/* This can be precomputed later */
    248 	j = 0;
    249 	for (i = 0; i < BCRYPT_BLOCKS; i++)
    250 		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
    251 
    252 	/* Now do the encryption */
    253 	for (k = 0; k < 64; k++)
    254 		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
    255 
    256 	for (i = 0; i < BCRYPT_BLOCKS; i++) {
    257 		ciphertext[4 * i + 3] = cdata[i] & 0xff;
    258 		cdata[i] = cdata[i] >> 8;
    259 		ciphertext[4 * i + 2] = cdata[i] & 0xff;
    260 		cdata[i] = cdata[i] >> 8;
    261 		ciphertext[4 * i + 1] = cdata[i] & 0xff;
    262 		cdata[i] = cdata[i] >> 8;
    263 		ciphertext[4 * i + 0] = cdata[i] & 0xff;
    264 	}
    265 
    266 
    267 	i = 0;
    268 	encrypted[i++] = '$';
    269 	encrypted[i++] = BCRYPT_VERSION;
    270 	if (minor)
    271 		encrypted[i++] = minor;
    272 	encrypted[i++] = '$';
    273 
    274 	snprintf(encrypted + i, 4, "%2.2u$", logr);
    275 
    276 	encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
    277 	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
    278 	    4 * BCRYPT_BLOCKS - 1);
    279 	return encrypted;
    280 }
    281 
    282 static void
    283 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
    284 {
    285 	u_int8_t *bp = buffer;
    286 	u_int8_t *p = data;
    287 	u_int8_t c1, c2;
    288 	while (p < data + len) {
    289 		c1 = *p++;
    290 		*bp++ = Base64Code[(c1 >> 2)];
    291 		c1 = (c1 & 0x03) << 4;
    292 		if (p >= data + len) {
    293 			*bp++ = Base64Code[c1];
    294 			break;
    295 		}
    296 		c2 = *p++;
    297 		c1 |= (c2 >> 4) & 0x0f;
    298 		*bp++ = Base64Code[c1];
    299 		c1 = (c2 & 0x0f) << 2;
    300 		if (p >= data + len) {
    301 			*bp++ = Base64Code[c1];
    302 			break;
    303 		}
    304 		c2 = *p++;
    305 		c1 |= (c2 >> 6) & 0x03;
    306 		*bp++ = Base64Code[c1];
    307 		*bp++ = Base64Code[c2 & 0x3f];
    308 	}
    309 	*bp = '\0';
    310 }
    311 #if 0
    312 void
    313 main()
    314 {
    315 	char    blubber[73];
    316 	char    salt[100];
    317 	char   *p;
    318 	salt[0] = '$';
    319 	salt[1] = BCRYPT_VERSION;
    320 	salt[2] = '$';
    321 
    322 	snprintf(salt + 3, 4, "%2.2u$", 5);
    323 
    324 	printf("24 bytes of salt: ");
    325 	fgets(salt + 6, 94, stdin);
    326 	salt[99] = 0;
    327 	printf("72 bytes of password: ");
    328 	fpurge(stdin);
    329 	fgets(blubber, 73, stdin);
    330 	blubber[72] = 0;
    331 
    332 	p = crypt(blubber, salt);
    333 	printf("Passwd entry: %s\n\n", p);
    334 
    335 	p = bcrypt_gensalt(5);
    336 	printf("Generated salt: %s\n", p);
    337 	p = crypt(blubber, p);
    338 	printf("Passwd entry: %s\n", p);
    339 }
    340 #endif
    341