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1/* $OpenBSD: bcrypt.c,v 1.12 1998/08/10 18:33:07 provos 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#if 0
49#include <stdio.h>
50#endif
51
52#include <stdio.h>
53#include <stdlib.h>
54#include <sys/types.h>
55#include <string.h>
56#include <pwd.h>
57#include <blf.h>
58
59/* This implementation is adaptable to current computing power.
60 * You can have up to 2^31 rounds which should be enough for some
61 * time to come.
62 */
63
64#define BCRYPT_VERSION '2'
65#define BCRYPT_MAXSALT 16 /* Precomputation is just so nice */
66#define BCRYPT_BLOCKS 6 /* Ciphertext blocks */
67#define BCRYPT_MINROUNDS 16 /* we have log2(rounds) in salt */
68
69char *bcrypt_gensalt __P((u_int8_t));
70
71static void encode_salt __P((char *, u_int8_t *, u_int16_t, u_int8_t));
72static void encode_base64 __P((u_int8_t *, u_int8_t *, u_int16_t));
73static void decode_base64 __P((u_int8_t *, u_int16_t, u_int8_t *));
74
75static char encrypted[_PASSWORD_LEN];
76static char gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
77static char error[] = ":";
78
79const static u_int8_t Base64Code[] =
80"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
81
82const static u_int8_t index_64[128] =
83{
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
100#ifdef __STDC__
101static void
102decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data)
103#else
104static void
105decode_base64(buffer, len, data)
106 u_int8_t *buffer;
107 u_int16_t len;
108 u_int8_t *data;
109#endif
110{
111 u_int8_t *bp = buffer;
112 u_int8_t *p = data;
113 u_int8_t c1, c2, c3, c4;
114 while (bp < buffer + len) {
115 c1 = CHAR64(*p);
116 c2 = CHAR64(*(p + 1));
117
118 /* Invalid data */
119 if (c1 == 255 || c2 == 255)
120 break;
121
122 *bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
123 if (bp >= buffer + len)
124 break;
125
126 c3 = CHAR64(*(p + 2));
127 if (c3 == 255)
128 break;
129
130 *bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
131 if (bp >= buffer + len)
132 break;
133
134 c4 = CHAR64(*(p + 3));
135 if (c4 == 255)
136 break;
137 *bp++ = ((c3 & 0x03) << 6) | c4;
138
139 p += 4;
140 }
141}
142
143#ifdef __STDC__
144static void
145encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
146#else
147static void
148encode_salt(salt, csalt, clen, logr)
149 char *salt;
150 u_int8_t *csalt;
151 u_int16_t clen;
152 u_int8_t logr;
153#endif
154{
155 salt[0] = '$';
156 salt[1] = BCRYPT_VERSION;
157 salt[2] = 'a';
158 salt[3] = '$';
159
160 snprintf(salt + 4, 4, "%2.2u$", logr);
161
162 encode_base64((u_int8_t *) salt + 7, csalt, clen);
163}
164/* Generates a salt for this version of crypt.
165 Since versions may change. Keeping this here
166 seems sensible.
167 */
168
169#ifdef __STDC__
170char *
171bcrypt_gensalt(u_int8_t log_rounds)
172#else
173char *
174bcrypt_gensalt(log_rounds)
175 u_int8_t log_rounds;
176#endif
177{
178 u_int8_t csalt[BCRYPT_MAXSALT];
179 u_int16_t i;
180 u_int32_t seed = 0;
181
182 for (i = 0; i < BCRYPT_MAXSALT; i++) {
183 if (i % 4 == 0)
184 seed = arc4random();
185 csalt[i] = seed & 0xff;
186 seed = seed >> 8;
187 }
188
189 if (log_rounds < 4)
190 log_rounds = 4;
191
192 encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
193 return gsalt;
194}
195/* We handle $Vers$log2(NumRounds)$salt+passwd$
196 i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
197
198char *
199bcrypt(key, salt)
200 const char *key;
201 const char *salt;
202{
203 blf_ctx state;
204 u_int32_t rounds, i, k;
205 u_int16_t j;
206 u_int8_t key_len, salt_len, logr, minor;
207 u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
208 u_int8_t csalt[BCRYPT_MAXSALT];
209 u_int32_t cdata[BCRYPT_BLOCKS];
210
211 /* Discard "$" identifier */
212 salt++;
213
214 if (*salt > BCRYPT_VERSION) {
215 /* How do I handle errors ? Return ':' */
216 return error;
217 }
218
219 /* Check for minor versions */
220 if (salt[1] != '$') {
221 switch (salt[1]) {
222 case 'a':
223 /* 'ab' should not yield the same as 'abab' */
224 minor = salt[1];
225 salt++;
226 break;
227 default:
228 return error;
229 }
230 } else
231 minor = 0;
232
233 /* Discard version + "$" identifier */
234 salt += 2;
235
236 if (salt[2] != '$')
237 /* Out of sync with passwd entry */
238 return error;
239
240 /* Computer power doesnt increase linear, 2^x should be fine */
241 if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
242 return error;
243
244 /* Discard num rounds + "$" identifier */
245 salt += 3;
246
247 /* We dont want the base64 salt but the raw data */
248 decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
249 salt_len = BCRYPT_MAXSALT;
250 key_len = strlen(key) + (minor >= 'a' ? 1 : 0);
251
252 /* Setting up S-Boxes and Subkeys */
253 Blowfish_initstate(&state);
254 Blowfish_expandstate(&state, csalt, salt_len,
255 (u_int8_t *) key, key_len);
256 for (k = 0; k < rounds; k++) {
257 Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
258 Blowfish_expand0state(&state, csalt, salt_len);
259 }
260
261 /* This can be precomputed later */
262 j = 0;
263 for (i = 0; i < BCRYPT_BLOCKS; i++)
264 cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
265
266 /* Now do the encryption */
267 for (k = 0; k < 64; k++)
268 blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
269
270 for (i = 0; i < BCRYPT_BLOCKS; i++) {
271 ciphertext[4 * i + 3] = cdata[i] & 0xff;
272 cdata[i] = cdata[i] >> 8;
273 ciphertext[4 * i + 2] = cdata[i] & 0xff;
274 cdata[i] = cdata[i] >> 8;
275 ciphertext[4 * i + 1] = cdata[i] & 0xff;
276 cdata[i] = cdata[i] >> 8;
277 ciphertext[4 * i + 0] = cdata[i] & 0xff;
278 }
279
280
281 i = 0;
282 encrypted[i++] = '$';
283 encrypted[i++] = BCRYPT_VERSION;
284 if (minor)
285 encrypted[i++] = minor;
286 encrypted[i++] = '$';
287
288 snprintf(encrypted + i, 4, "%2.2u$", logr);
289
290 encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
291 encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
292 4 * BCRYPT_BLOCKS - 1);
293 return encrypted;
294}
295
296#ifdef __STDC__
297static void
298encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
299#else
300static void
301encode_base64(buffer, data, len)
302 u_int8_t *buffer;
303 u_int8_t *data;
304 u_int16_t len;
305#endif
306{
307 u_int8_t *bp = buffer;
308 u_int8_t *p = data;
309 u_int8_t c1, c2;
310 while (p < data + len) {
311 c1 = *p++;
312 *bp++ = Base64Code[(c1 >> 2)];
313 c1 = (c1 & 0x03) << 4;
314 if (p >= data + len) {
315 *bp++ = Base64Code[c1];
316 break;
317 }
318 c2 = *p++;
319 c1 |= (c2 >> 4) & 0x0f;
320 *bp++ = Base64Code[c1];
321 c1 = (c2 & 0x0f) << 2;
322 if (p >= data + len) {
323 *bp++ = Base64Code[c1];
324 break;
325 }
326 c2 = *p++;
327 c1 |= (c2 >> 6) & 0x03;
328 *bp++ = Base64Code[c1];
329 *bp++ = Base64Code[c2 & 0x3f];
330 }
331 *bp = '\0';
332}
333#if 0
334void
335main()
336{
337 char blubber[73];
338 char salt[100];
339 char *p;
340 salt[0] = '$';
341 salt[1] = BCRYPT_VERSION;
342 salt[2] = '$';
343
344 snprintf(salt + 3, 4, "%2.2u$", 5);
345
346 printf("24 bytes of salt: ");
347 fgets(salt + 6, 94, stdin);
348 salt[99] = 0;
349 printf("72 bytes of password: ");
350 fpurge(stdin);
351 fgets(blubber, 73, stdin);
352 blubber[72] = 0;
353
354 p = crypt(blubber, salt);
355 printf("Passwd entry: %s\n\n", p);
356
357 p = bcrypt_gensalt(5);
358 printf("Generated salt: %s\n", p);
359 p = crypt(blubber, p);
360 printf("Passwd entry: %s\n", p);
361}
362#endif