crypt-blowfish.c revision 266816 
1/*	$OpenBSD: bcrypt.c,v 1.29 2014/02/24 19:45:43 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#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: stable/10/secure/lib/libcrypt/crypt-blowfish.c 266816 2014-05-28 18:51:49Z delphij $");
35
36/* This password hashing algorithm was designed by David Mazieres
37 * <dm@lcs.mit.edu> and works as follows:
38 *
39 * 1. state := InitState ()
40 * 2. state := ExpandKey (state, salt, password)
41 * 3. REPEAT rounds:
42 *      state := ExpandKey (state, 0, password)
43 *	state := ExpandKey (state, 0, salt)
44 * 4. ctext := "OrpheanBeholderScryDoubt"
45 * 5. REPEAT 64:
46 * 	ctext := Encrypt_ECB (state, ctext);
47 * 6. RETURN Concatenate (salt, ctext);
48 *
49 */
50
51/*
52 * FreeBSD implementation by Paul Herman <pherman@frenchfries.net>
53 * and updated by Xin Li <delphij@FreeBSD.org>
54 */
55
56#include <stdio.h>
57#include <stdlib.h>
58#include <sys/types.h>
59#include <string.h>
60#include <pwd.h>
61#include "blowfish.h"
62#include "crypt.h"
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_MINLOGROUNDS 4	/* we have log2(rounds) in salt */
73
74
75static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
76static void decode_base64(u_int8_t *, u_int16_t, const u_int8_t *);
77
78static char    encrypted[_PASSWORD_LEN];
79
80const static u_int8_t Base64Code[] =
81"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
82
83const static u_int8_t index_64[128] = {
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
100static void
101decode_base64(u_int8_t *buffer, u_int16_t len, const u_int8_t *data)
102{
103	u_int8_t *bp = buffer;
104	const 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/* We handle $Vers$log2(NumRounds)$salt+passwd$
136   i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
137
138char   *
139crypt_blowfish(const char *key, const char *salt)
140{
141	blf_ctx state;
142	u_int32_t rounds, i, k;
143	u_int16_t j;
144	size_t key_len;
145	u_int8_t salt_len, logr, minr;
146	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
147	u_int8_t csalt[BCRYPT_MAXSALT];
148	u_int32_t cdata[BCRYPT_BLOCKS];
149	char arounds[3];
150
151	/* Defaults */
152	minr = 'b';
153	logr = BCRYPT_MINLOGROUNDS;
154	rounds = 1U << logr;
155
156	if (*salt == '$') {
157		/* Discard "$" identifier */
158		salt++;
159
160		if (*salt > BCRYPT_VERSION) {
161			/* How do I handle errors ? Return NULL */
162			return NULL;
163		}
164
165		/* Check for minor versions */
166		if (salt[1] != '$') {
167			 switch (salt[1]) {
168			 case 'a':	/* 'ab' should not yield the same as 'abab' */
169			 case 'b':	/* cap input length at 72 bytes */
170				 minr = salt[1];
171				 salt++;
172				 break;
173			 default:
174				 return NULL;
175			 }
176		} else
177			 minr = 0;
178
179		/* Discard version + "$" identifier */
180		salt += 2;
181
182		if (salt[2] != '$')
183			/* Out of sync with passwd entry */
184			return NULL;
185
186		memcpy(arounds, salt, sizeof(arounds));
187		if (arounds[sizeof(arounds) - 1] != '$')
188			return NULL;
189		arounds[sizeof(arounds) - 1] = 0;
190		logr = strtonum(arounds, BCRYPT_MINLOGROUNDS, 31, NULL);
191		if (logr == 0)
192			return NULL;
193		/* Computer power doesn't increase linearly, 2^x should be fine */
194		rounds = 1U << logr;
195
196		/* Discard num rounds + "$" identifier */
197		salt += 3;
198	}
199
200	if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
201		return NULL;
202
203	/* We dont want the base64 salt but the raw data */
204	decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *) salt);
205	salt_len = BCRYPT_MAXSALT;
206	if (minr <= 'a')
207		key_len = (u_int8_t)(strlen(key) + (minr >= 'a' ? 1 : 0));
208	else {
209		/* strlen() returns a size_t, but the function calls
210		 * below result in implicit casts to a narrower integer
211		 * type, so cap key_len at the actual maximum supported
212		 * length here to avoid integer wraparound */
213		key_len = strlen(key);
214		if (key_len > 72)
215			key_len = 72;
216		key_len++; /* include the NUL */
217	}
218
219	/* Setting up S-Boxes and Subkeys */
220	Blowfish_initstate(&state);
221	Blowfish_expandstate(&state, csalt, salt_len,
222	    (const u_int8_t *) key, key_len);
223	for (k = 0; k < rounds; k++) {
224		Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
225		Blowfish_expand0state(&state, csalt, salt_len);
226	}
227
228	/* This can be precomputed later */
229	j = 0;
230	for (i = 0; i < BCRYPT_BLOCKS; i++)
231		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
232
233	/* Now do the encryption */
234	for (k = 0; k < 64; k++)
235		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
236
237	for (i = 0; i < BCRYPT_BLOCKS; i++) {
238		ciphertext[4 * i + 3] = cdata[i] & 0xff;
239		cdata[i] = cdata[i] >> 8;
240		ciphertext[4 * i + 2] = cdata[i] & 0xff;
241		cdata[i] = cdata[i] >> 8;
242		ciphertext[4 * i + 1] = cdata[i] & 0xff;
243		cdata[i] = cdata[i] >> 8;
244		ciphertext[4 * i + 0] = cdata[i] & 0xff;
245	}
246
247
248	i = 0;
249	encrypted[i++] = '$';
250	encrypted[i++] = BCRYPT_VERSION;
251	if (minr)
252		encrypted[i++] = minr;
253	encrypted[i++] = '$';
254
255	snprintf(encrypted + i, 4, "%2.2u$", logr);
256
257	encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
258	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
259	    4 * BCRYPT_BLOCKS - 1);
260	memset(&state, 0, sizeof(state));
261	memset(ciphertext, 0, sizeof(ciphertext));
262	memset(csalt, 0, sizeof(csalt));
263	memset(cdata, 0, sizeof(cdata));
264	return encrypted;
265}
266
267static void
268encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
269{
270	u_int8_t *bp = buffer;
271	u_int8_t *p = data;
272	u_int8_t c1, c2;
273	while (p < data + len) {
274		c1 = *p++;
275		*bp++ = Base64Code[(c1 >> 2)];
276		c1 = (c1 & 0x03) << 4;
277		if (p >= data + len) {
278			*bp++ = Base64Code[c1];
279			break;
280		}
281		c2 = *p++;
282		c1 |= (c2 >> 4) & 0x0f;
283		*bp++ = Base64Code[c1];
284		c1 = (c2 & 0x0f) << 2;
285		if (p >= data + len) {
286			*bp++ = Base64Code[c1];
287			break;
288		}
289		c2 = *p++;
290		c1 |= (c2 >> 6) & 0x03;
291		*bp++ = Base64Code[c1];
292		*bp++ = Base64Code[c2 & 0x3f];
293	}
294	*bp = '\0';
295}
296#if 0
297void
298main()
299{
300	char    blubber[73];
301	char    salt[100];
302	char   *p;
303	salt[0] = '$';
304	salt[1] = BCRYPT_VERSION;
305	salt[2] = '$';
306
307	snprintf(salt + 3, 4, "%2.2u$", 5);
308
309	printf("24 bytes of salt: ");
310	fgets(salt + 6, sizeof(salt) - 6, stdin);
311	salt[99] = 0;
312	printf("72 bytes of password: ");
313	fpurge(stdin);
314	fgets(blubber, sizeof(blubber), stdin);
315	blubber[72] = 0;
316
317	p = crypt(blubber, salt);
318	printf("Passwd entry: %s\n\n", p);
319
320	p = bcrypt_gensalt(5);
321	printf("Generated salt: %s\n", p);
322	p = crypt(blubber, p);
323	printf("Passwd entry: %s\n", p);
324}
325#endif
326