xref: /netbsd-src/lib/libcrypt/bcrypt.c (revision 8b0f9554ff8762542c4defc4f70e1eb76fb508fa) 
1 /*	$NetBSD: bcrypt.c,v 1.9 2006/10/27 19:39:11 drochner Exp $	*/
2 /*	$OpenBSD: bcrypt.c,v 1.16 2002/02/19 19:39:36 millert Exp $	*/
3 
4 /*
5  * Copyright 1997 Niels Provos <provos@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@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 #include <sys/cdefs.h>
49 __RCSID("$NetBSD: bcrypt.c,v 1.9 2006/10/27 19:39:11 drochner Exp $");
50 
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <sys/types.h>
54 #include <string.h>
55 #include <pwd.h>
56 #include <errno.h>
57 #include <limits.h>
58 
59 #include "crypt.h"
60 #include "blowfish.c"
61 
62 /* This implementation is adaptable to current computing power.
63  * You can have up to 2^31 rounds which should be enough for some
64  * time to come.
65  */
66 
67 #define BCRYPT_VERSION '2'
68 #define BCRYPT_MAXSALT 16	/* Precomputation is just so nice */
69 #define BCRYPT_MAXSALTLEN 	(BCRYPT_MAXSALT * 4 / 3 + 1)
70 #define BCRYPT_BLOCKS 6		/* Ciphertext blocks */
71 #define BCRYPT_MINROUNDS 16	/* we have log2(rounds) in salt */
72 
73 static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t);
74 static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
75 static void decode_base64(u_int8_t *, u_int16_t, const u_int8_t *);
76 
77 char *__bcrypt(const char *, const char *);	/* XXX */
78 
79 static char    encrypted[_PASSWORD_LEN];
80 static char    error[] = ":";
81 
82 static const u_int8_t Base64Code[] =
83 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
84 
85 char *bcrypt_gensalt(u_int8_t);
86 
87 static const 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, const u_int8_t *data)
107 {
108 	u_int8_t *bp = buffer;
109 	const 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++ = ((u_int32_t)c1 << 2) | (((u_int32_t)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++ = (((u_int32_t)c2 & 0x0f) << 4) | (((uint32_t)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 int
154 __gensalt_blowfish(char *salt, size_t saltlen, const char *option)
155 {
156 	size_t i;
157 	u_int32_t seed = 0;
158 	u_int8_t csalt[BCRYPT_MAXSALT];
159 	unsigned long nrounds;
160 	char *ep;
161 
162 	if (saltlen < BCRYPT_MAXSALTLEN) {
163 		errno = ENOSPC;
164 		return -1;
165 	}
166 	if (option == NULL) {
167 		errno = EINVAL;
168 		return -1;
169 	}
170 	nrounds = strtoul(option, &ep, 0);
171 	if (option == ep || *ep) {
172 		errno = EINVAL;
173 		return -1;
174 	}
175 	if (errno == ERANGE && nrounds == ULONG_MAX)
176 		return -1;
177 
178 	if (nrounds > 255) {
179 		errno = EINVAL;
180 		return -1;
181 	}
182 
183 	if (nrounds < 4)
184 		nrounds = 4;
185 
186 	for (i = 0; i < BCRYPT_MAXSALT; i++) {
187 		if (i % 4 == 0)
188 			seed = arc4random();
189 		csalt[i] = seed & 0xff;
190 		seed = seed >> 8;
191 	}
192 	encode_salt(salt, csalt, BCRYPT_MAXSALT, (u_int8_t)nrounds);
193 	return 0;
194 }
195 
196 /* Generates a salt for this version of crypt.
197    Since versions may change. Keeping this here
198    seems sensible.
199    XXX: compat.
200  */
201 char *
202 bcrypt_gensalt(u_int8_t log_rounds)
203 {
204 	static char gsalt[BCRYPT_MAXSALTLEN];
205 	char num[10];
206 
207 	(void)snprintf(num, sizeof(num), "%d", log_rounds);
208 	if (__gensalt_blowfish(gsalt, sizeof(gsalt), num) == -1)
209 		return NULL;
210 	return gsalt;
211 }
212 
213 /* We handle $Vers$log2(NumRounds)$salt+passwd$
214    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
215 
216 char   *
217 __bcrypt(key, salt)
218 	const char   *key;
219 	const char   *salt;
220 {
221 	blf_ctx state;
222 	u_int32_t rounds, i, k;
223 	u_int16_t j;
224 	u_int8_t key_len, salt_len, logr, minor;
225 	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
226 	u_int8_t csalt[BCRYPT_MAXSALT];
227 	u_int32_t cdata[BCRYPT_BLOCKS];
228 
229 	/* Discard "$" identifier */
230 	salt++;
231 
232 	if (*salt > BCRYPT_VERSION) {
233 		/* How do I handle errors ? Return ':' */
234 		return error;
235 	}
236 
237 	/* Check for minor versions */
238 	if (salt[1] != '$') {
239 		 switch (salt[1]) {
240 		 case 'a':
241 			 /* 'ab' should not yield the same as 'abab' */
242 			 minor = salt[1];
243 			 salt++;
244 			 break;
245 		 default:
246 			 return error;
247 		 }
248 	} else
249 		 minor = 0;
250 
251 	/* Discard version + "$" identifier */
252 	salt += 2;
253 
254 	if (salt[2] != '$')
255 		/* Out of sync with passwd entry */
256 		return error;
257 
258 	/* Computer power doesn't increase linear, 2^x should be fine */
259 	if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
260 		return error;
261 
262 	/* Discard num rounds + "$" identifier */
263 	salt += 3;
264 
265 	if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
266 		return error;
267 
268 	/* We dont want the base64 salt but the raw data */
269 	decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *)salt);
270 	salt_len = BCRYPT_MAXSALT;
271 	key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
272 
273 	/* Setting up S-Boxes and Subkeys */
274 	Blowfish_initstate(&state);
275 	Blowfish_expandstate(&state, csalt, salt_len,
276 	    (const u_int8_t *) key, key_len);
277 	for (k = 0; k < rounds; k++) {
278 		Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
279 		Blowfish_expand0state(&state, csalt, salt_len);
280 	}
281 
282 	/* This can be precomputed later */
283 	j = 0;
284 	for (i = 0; i < BCRYPT_BLOCKS; i++)
285 		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
286 
287 	/* Now do the encryption */
288 	for (k = 0; k < 64; k++)
289 		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
290 
291 	for (i = 0; i < BCRYPT_BLOCKS; i++) {
292 		ciphertext[4 * i + 3] = cdata[i] & 0xff;
293 		cdata[i] = cdata[i] >> 8;
294 		ciphertext[4 * i + 2] = cdata[i] & 0xff;
295 		cdata[i] = cdata[i] >> 8;
296 		ciphertext[4 * i + 1] = cdata[i] & 0xff;
297 		cdata[i] = cdata[i] >> 8;
298 		ciphertext[4 * i + 0] = cdata[i] & 0xff;
299 	}
300 
301 
302 	i = 0;
303 	encrypted[i++] = '$';
304 	encrypted[i++] = BCRYPT_VERSION;
305 	if (minor)
306 		encrypted[i++] = minor;
307 	encrypted[i++] = '$';
308 
309 	snprintf(encrypted + i, 4, "%2.2u$", logr);
310 
311 	encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
312 	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
313 	    4 * BCRYPT_BLOCKS - 1);
314 	return encrypted;
315 }
316 
317 static void
318 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
319 {
320 	u_int8_t *bp = buffer;
321 	u_int8_t *p = data;
322 	u_int8_t c1, c2;
323 	while (p < data + len) {
324 		c1 = *p++;
325 		*bp++ = Base64Code[((u_int32_t)c1 >> 2)];
326 		c1 = (c1 & 0x03) << 4;
327 		if (p >= data + len) {
328 			*bp++ = Base64Code[c1];
329 			break;
330 		}
331 		c2 = *p++;
332 		c1 |= ((u_int32_t)c2 >> 4) & 0x0f;
333 		*bp++ = Base64Code[c1];
334 		c1 = (c2 & 0x0f) << 2;
335 		if (p >= data + len) {
336 			*bp++ = Base64Code[c1];
337 			break;
338 		}
339 		c2 = *p++;
340 		c1 |= ((u_int32_t)c2 >> 6) & 0x03;
341 		*bp++ = Base64Code[c1];
342 		*bp++ = Base64Code[c2 & 0x3f];
343 	}
344 	*bp = '\0';
345 }
346 #if 0
347 void
348 main()
349 {
350 	char    blubber[73];
351 	char    salt[100];
352 	char   *p;
353 	salt[0] = '$';
354 	salt[1] = BCRYPT_VERSION;
355 	salt[2] = '$';
356 
357 	snprintf(salt + 3, 4, "%2.2u$", 5);
358 
359 	printf("24 bytes of salt: ");
360 	fgets(salt + 6, 94, stdin);
361 	salt[99] = 0;
362 	printf("72 bytes of password: ");
363 	fpurge(stdin);
364 	fgets(blubber, 73, stdin);
365 	blubber[72] = 0;
366 
367 	p = crypt(blubber, salt);
368 	printf("Passwd entry: %s\n\n", p);
369 
370 	p = bcrypt_gensalt(5);
371 	printf("Generated salt: %s\n", p);
372 	p = crypt(blubber, p);
373 	printf("Passwd entry: %s\n", p);
374 }
375 #endif
376