xref: /freebsd/secure/lib/libcrypt/crypt-blowfish.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
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 
49 /*
50  * FreeBSD implementation by Paul Herman <pherman@frenchfries.net>
51  */
52 
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <sys/types.h>
56 #include <string.h>
57 #include <pwd.h>
58 #include "blowfish.h"
59 #include "crypt.h"
60 
61 /* This implementation is adaptable to current computing power.
62  * You can have up to 2^31 rounds which should be enough for some
63  * time to come.
64  */
65 
66 #define BCRYPT_VERSION '2'
67 #define BCRYPT_MAXSALT 16	/* Precomputation is just so nice */
68 #define BCRYPT_BLOCKS 6		/* Ciphertext blocks */
69 #define BCRYPT_MINROUNDS 16	/* we have log2(rounds) in salt */
70 
71 static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
72 static void decode_base64(u_int8_t *, u_int16_t, const u_int8_t *);
73 
74 static char    encrypted[_PASSWORD_LEN];
75 static char    error[] = ":";
76 
77 static const u_int8_t Base64Code[] =
78 "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
79 
80 static const u_int8_t index_64[128] =
81 {
82 	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
83 	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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, 0, 1, 54, 55,
87 	56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
88 	255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
89 	7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
90 	17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
91 	255, 255, 255, 255, 255, 255, 28, 29, 30,
92 	31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
93 	41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
94 	51, 52, 53, 255, 255, 255, 255, 255
95 };
96 #define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
97 
98 static void
99 decode_base64(u_int8_t *buffer, u_int16_t len, const u_int8_t *data)
100 {
101 	u_int8_t *bp = buffer;
102 	const u_int8_t *p = data;
103 	u_int8_t c1, c2, c3, c4;
104 	while (bp < buffer + len) {
105 		c1 = CHAR64(*p);
106 		c2 = CHAR64(*(p + 1));
107 
108 		/* Invalid data */
109 		if (c1 == 255 || c2 == 255)
110 			break;
111 
112 		*bp++ = (u_int8_t)((c1 << 2) | ((c2 & 0x30) >> 4));
113 		if (bp >= buffer + len)
114 			break;
115 
116 		c3 = CHAR64(*(p + 2));
117 		if (c3 == 255)
118 			break;
119 
120 		*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
121 		if (bp >= buffer + len)
122 			break;
123 
124 		c4 = CHAR64(*(p + 3));
125 		if (c4 == 255)
126 			break;
127 		*bp++ = ((c3 & 0x03) << 6) | c4;
128 
129 		p += 4;
130 	}
131 }
132 
133 /* We handle $Vers$log2(NumRounds)$salt+passwd$
134    i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
135 
136 char   *
137 crypt_blowfish(const char *key, const char *salt)
138 {
139 	blf_ctx state;
140 	u_int32_t rounds, i, k;
141 	u_int16_t j;
142 	u_int8_t key_len, salt_len, logr, minr;
143 	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
144 	u_int8_t csalt[BCRYPT_MAXSALT];
145 	u_int32_t cdata[BCRYPT_BLOCKS];
146 	static const char     *magic = "$2a$04$";
147 
148 		/* Defaults */
149 	minr = 'a';
150 	logr = 4;
151 	rounds = 1 << logr;
152 
153         /* If it starts with the magic string, then skip that */
154 	if(!strncmp(salt, magic, strlen(magic))) {
155 		salt += strlen(magic);
156 	}
157 	else if (*salt == '$') {
158 
159 		/* Discard "$" identifier */
160 		salt++;
161 
162 		if (*salt > BCRYPT_VERSION) {
163 			/* How do I handle errors ? Return ':' */
164 			return error;
165 		}
166 
167 		/* Check for minor versions */
168 		if (salt[1] != '$') {
169 			 switch (salt[1]) {
170 			 case 'a':
171 				 /* 'ab' should not yield the same as 'abab' */
172 				 minr = (u_int8_t)salt[1];
173 				 salt++;
174 				 break;
175 			 default:
176 				 return error;
177 			 }
178 		} else
179 			 minr = 0;
180 
181 		/* Discard version + "$" identifier */
182 		salt += 2;
183 
184 		if (salt[2] != '$')
185 			/* Out of sync with passwd entry */
186 			return error;
187 
188 		/* Computer power doesnt increase linear, 2^x should be fine */
189 		logr = (u_int8_t)atoi(salt);
190 		rounds = 1 << logr;
191 		if (rounds < BCRYPT_MINROUNDS)
192 			return error;
193 
194 		/* Discard num rounds + "$" identifier */
195 		salt += 3;
196 	}
197 
198 
199 	/* We dont want the base64 salt but the raw data */
200 	decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *)salt);
201 	salt_len = BCRYPT_MAXSALT;
202 	key_len = (u_int8_t)(strlen(key) + (minr >= 'a' ? 1 : 0));
203 
204 	/* Setting up S-Boxes and Subkeys */
205 	Blowfish_initstate(&state);
206 	Blowfish_expandstate(&state, csalt, salt_len,
207 	    (const u_int8_t *) key, key_len);
208 	for (k = 0; k < rounds; k++) {
209 		Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
210 		Blowfish_expand0state(&state, csalt, salt_len);
211 	}
212 
213 	/* This can be precomputed later */
214 	j = 0;
215 	for (i = 0; i < BCRYPT_BLOCKS; i++)
216 		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
217 
218 	/* Now do the encryption */
219 	for (k = 0; k < 64; k++)
220 		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
221 
222 	for (i = 0; i < BCRYPT_BLOCKS; i++) {
223 		ciphertext[4 * i + 3] = cdata[i] & 0xff;
224 		cdata[i] = cdata[i] >> 8;
225 		ciphertext[4 * i + 2] = cdata[i] & 0xff;
226 		cdata[i] = cdata[i] >> 8;
227 		ciphertext[4 * i + 1] = cdata[i] & 0xff;
228 		cdata[i] = cdata[i] >> 8;
229 		ciphertext[4 * i + 0] = cdata[i] & 0xff;
230 	}
231 
232 
233 	i = 0;
234 	encrypted[i++] = '$';
235 	encrypted[i++] = BCRYPT_VERSION;
236 	if (minr)
237 		encrypted[i++] = (int8_t)minr;
238 	encrypted[i++] = '$';
239 
240 	snprintf(encrypted + i, 4, "%2.2u$", logr);
241 
242 	encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
243 	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
244 	    4 * BCRYPT_BLOCKS - 1);
245 	return encrypted;
246 }
247 
248 static void
249 encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
250 {
251 	u_int8_t *bp = buffer;
252 	u_int8_t *p = data;
253 	u_int8_t c1, c2;
254 	while (p < data + len) {
255 		c1 = *p++;
256 		*bp++ = Base64Code[(c1 >> 2)];
257 		c1 = (c1 & 0x03) << 4;
258 		if (p >= data + len) {
259 			*bp++ = Base64Code[c1];
260 			break;
261 		}
262 		c2 = *p++;
263 		c1 |= (c2 >> 4) & 0x0f;
264 		*bp++ = Base64Code[c1];
265 		c1 = (c2 & 0x0f) << 2;
266 		if (p >= data + len) {
267 			*bp++ = Base64Code[c1];
268 			break;
269 		}
270 		c2 = *p++;
271 		c1 |= (c2 >> 6) & 0x03;
272 		*bp++ = Base64Code[c1];
273 		*bp++ = Base64Code[c2 & 0x3f];
274 	}
275 	*bp = '\0';
276 }
277 
278 #if 0
279 void
280 main()
281 {
282 	char    blubber[73];
283 	char    salt[100];
284 	char   *p;
285 	salt[0] = '$';
286 	salt[1] = BCRYPT_VERSION;
287 	salt[2] = '$';
288 
289 	snprintf(salt + 3, 4, "%2.2u$", 5);
290 
291 	printf("24 bytes of salt: ");
292 	fgets(salt + 6, 94, stdin);
293 	salt[99] = 0;
294 	printf("72 bytes of password: ");
295 	fpurge(stdin);
296 	fgets(blubber, 73, stdin);
297 	blubber[72] = 0;
298 
299 	p = crypt(blubber, salt);
300 	printf("Passwd entry: %s\n\n", p);
301 
302 	p = bcrypt_gensalt(5);
303 	printf("Generated salt: %s\n", p);
304 	p = crypt(blubber, p);
305 	printf("Passwd entry: %s\n", p);
306 }
307 #endif
308