1/*	$NetBSD: bcrypt.c,v 1.22 2021/10/16 10:53:33 nia 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 1.22 2021/10/16 10:53:33 nia 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 	(7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1)
70#define BCRYPT_BLOCKS 6		/* Ciphertext blocks */
71#define BCRYPT_MINROUNDS 16	/* we have log2(rounds) in salt */
72
73static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t);
74static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
75static void decode_base64(u_int8_t *, u_int16_t, const u_int8_t *);
76
77crypt_private char *__bcrypt(const char *, const char *);	/* XXX */
78
79static char    encrypted[_PASSWORD_LEN];
80
81static const u_int8_t Base64Code[] =
82"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
83
84char *bcrypt_gensalt(u_int8_t);
85
86static const u_int8_t index_64[128] =
87{
88	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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, 0, 1, 54, 55,
93	56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
94	255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
95	7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
96	17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
97	255, 255, 255, 255, 255, 255, 28, 29, 30,
98	31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
99	41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
100	51, 52, 53, 255, 255, 255, 255, 255
101};
102#define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
103
104static void
105decode_base64(u_int8_t *buffer, u_int16_t len, const u_int8_t *data)
106{
107	u_int8_t *bp = buffer;
108	const u_int8_t *p = data;
109	u_int8_t c1, c2, c3, c4;
110	while (bp < buffer + len) {
111		c1 = CHAR64(*p);
112		c2 = CHAR64(*(p + 1));
113
114		/* Invalid data */
115		if (c1 == 255 || c2 == 255)
116			break;
117
118		*bp++ = ((u_int32_t)c1 << 2) | (((u_int32_t)c2 & 0x30) >> 4);
119		if (bp >= buffer + len)
120			break;
121
122		c3 = CHAR64(*(p + 2));
123		if (c3 == 255)
124			break;
125
126		*bp++ = (((u_int32_t)c2 & 0x0f) << 4) | (((uint32_t)c3 & 0x3c) >> 2);
127		if (bp >= buffer + len)
128			break;
129
130		c4 = CHAR64(*(p + 3));
131		if (c4 == 255)
132			break;
133		*bp++ = ((c3 & 0x03) << 6) | c4;
134
135		p += 4;
136	}
137}
138
139static void
140encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
141{
142	salt[0] = '$';
143	salt[1] = BCRYPT_VERSION;
144	salt[2] = 'a';
145	salt[3] = '$';
146
147	snprintf(salt + 4, 4, "%2.2u$", logr);
148
149	encode_base64((u_int8_t *) salt + 7, csalt, clen);
150}
151
152crypt_private int
153__gensalt_blowfish(char *salt, size_t saltlen, const char *option)
154{
155	size_t i;
156	u_int32_t seed = 0;
157	u_int8_t csalt[BCRYPT_MAXSALT];
158	unsigned long nrounds;
159	char *ep;
160
161	if (saltlen < BCRYPT_MAXSALTLEN) {
162		errno = ENOSPC;
163		return -1;
164	}
165	if (option == NULL) {
166		errno = EINVAL;
167		return -1;
168	}
169	nrounds = strtoul(option, &ep, 0);
170	if (option == ep || *ep) {
171		errno = EINVAL;
172		return -1;
173	}
174	if (errno == ERANGE && nrounds == ULONG_MAX)
175		return -1;
176
177	if (nrounds < 4)
178		nrounds = 4;
179	else if (nrounds > 31)
180		nrounds = 31;
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	encode_salt(salt, csalt, BCRYPT_MAXSALT, (u_int8_t)nrounds);
189	return 0;
190}
191
192/* Generates a salt for this version of crypt.
193   Since versions may change. Keeping this here
194   seems sensible.
195   XXX: compat.
196 */
197char *
198bcrypt_gensalt(u_int8_t log_rounds)
199{
200	static char gsalt[BCRYPT_MAXSALTLEN];
201	char num[10];
202
203	(void)snprintf(num, sizeof(num), "%d", log_rounds);
204	if (__gensalt_blowfish(gsalt, sizeof(gsalt), num) == -1)
205		return NULL;
206	return gsalt;
207}
208
209/* We handle $Vers$log2(NumRounds)$salt+passwd$
210   i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
211
212crypt_private char   *
213__bcrypt(const char *key, const char *salt)
214{
215	blf_ctx state;
216	u_int32_t rounds, i, k;
217	u_int16_t j;
218	u_int8_t key_len, salt_len, logr, minor;
219	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
220	u_int8_t csalt[BCRYPT_MAXSALT];
221	u_int32_t cdata[BCRYPT_BLOCKS];
222	int n;
223	size_t len;
224
225	/* Discard "$" identifier */
226	salt++;
227
228	if (*salt > BCRYPT_VERSION)
229		return NULL;
230
231	/* Check for minor versions */
232	if (salt[1] != '$') {
233		switch (salt[1]) {
234		case 'a':
235			/* 'ab' should not yield the same as 'abab' */
236			minor = salt[1];
237			salt++;
238			break;
239		default:
240			return NULL;
241		}
242	} else
243		 minor = 0;
244
245	/* Discard version + "$" identifier */
246	salt += 2;
247
248	if (salt[2] != '$')
249		/* Out of sync with passwd entry */
250		return NULL;
251
252	/* Computer power doesn't increase linear, 2^x should be fine */
253	n = atoi(salt);
254	if (n > 31 || n < 0)
255		return NULL;
256	logr = (u_int8_t)n;
257	if ((rounds = (u_int32_t) 1 << logr) < BCRYPT_MINROUNDS)
258		return NULL;
259
260	/* Discard num rounds + "$" identifier */
261	salt += 3;
262
263	if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
264		return NULL;
265
266	/* We dont want the base64 salt but the raw data */
267	decode_base64(csalt, BCRYPT_MAXSALT, (const u_int8_t *)salt);
268	salt_len = BCRYPT_MAXSALT;
269	len = strlen(key);
270	if (len > 72)
271		key_len = 72;
272	else
273		key_len = (uint8_t)len;
274	key_len += minor >= 'a' ? 1 : 0;
275
276	/* Setting up S-Boxes and Subkeys */
277	Blowfish_initstate(&state);
278	Blowfish_expandstate(&state, csalt, salt_len,
279	    (const u_int8_t *) key, key_len);
280	for (k = 0; k < rounds; k++) {
281		Blowfish_expand0state(&state, (const u_int8_t *) key, key_len);
282		Blowfish_expand0state(&state, csalt, salt_len);
283	}
284
285	/* This can be precomputed later */
286	j = 0;
287	for (i = 0; i < BCRYPT_BLOCKS; i++)
288		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
289
290	/* Now do the encryption */
291	for (k = 0; k < 64; k++)
292		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
293
294	for (i = 0; i < BCRYPT_BLOCKS; i++) {
295		ciphertext[4 * i + 3] = cdata[i] & 0xff;
296		cdata[i] = cdata[i] >> 8;
297		ciphertext[4 * i + 2] = cdata[i] & 0xff;
298		cdata[i] = cdata[i] >> 8;
299		ciphertext[4 * i + 1] = cdata[i] & 0xff;
300		cdata[i] = cdata[i] >> 8;
301		ciphertext[4 * i + 0] = cdata[i] & 0xff;
302	}
303
304
305	i = 0;
306	encrypted[i++] = '$';
307	encrypted[i++] = BCRYPT_VERSION;
308	if (minor)
309		encrypted[i++] = minor;
310	encrypted[i++] = '$';
311
312	snprintf(encrypted + i, 4, "%2.2u$", logr);
313
314	encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
315	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
316	    4 * BCRYPT_BLOCKS - 1);
317	explicit_memset(&state, 0, sizeof(state));
318	return encrypted;
319}
320
321static void
322encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
323{
324	u_int8_t *bp = buffer;
325	u_int8_t *p = data;
326	u_int8_t c1, c2;
327	while (p < data + len) {
328		c1 = *p++;
329		*bp++ = Base64Code[((u_int32_t)c1 >> 2)];
330		c1 = (c1 & 0x03) << 4;
331		if (p >= data + len) {
332			*bp++ = Base64Code[c1];
333			break;
334		}
335		c2 = *p++;
336		c1 |= ((u_int32_t)c2 >> 4) & 0x0f;
337		*bp++ = Base64Code[c1];
338		c1 = (c2 & 0x0f) << 2;
339		if (p >= data + len) {
340			*bp++ = Base64Code[c1];
341			break;
342		}
343		c2 = *p++;
344		c1 |= ((u_int32_t)c2 >> 6) & 0x03;
345		*bp++ = Base64Code[c1];
346		*bp++ = Base64Code[c2 & 0x3f];
347	}
348	*bp = '\0';
349}
350#if 0
351void
352main()
353{
354	char    blubber[73];
355	char    salt[100];
356	char   *p;
357	salt[0] = '$';
358	salt[1] = BCRYPT_VERSION;
359	salt[2] = '$';
360
361	snprintf(salt + 3, 4, "%2.2u$", 5);
362
363	printf("24 bytes of salt: ");
364	fgets(salt + 6, 94, stdin);
365	salt[99] = 0;
366	printf("72 bytes of password: ");
367	fpurge(stdin);
368	fgets(blubber, 73, stdin);
369	blubber[72] = 0;
370
371	p = crypt(blubber, salt);
372	printf("Passwd entry: %s\n\n", p);
373
374	p = bcrypt_gensalt(5);
375	printf("Generated salt: %s\n", p);
376	p = crypt(blubber, p);
377	printf("Passwd entry: %s\n", p);
378}
379#endif
380