1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 Poul-Henning Kamp
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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/types.h>
33
34#include <err.h>
35#include <md5.h>
36#include <stdio.h>
37#include <string.h>
38#include <unistd.h>
39
40#include "crypt.h"
41
42/*
43 * UNIX password
44 */
45
46int
47crypt_md5(const char *pw, const char *salt, char *buffer)
48{
49	MD5_CTX	ctx,ctx1;
50	unsigned long l;
51	int sl, pl;
52	u_int i;
53	u_char final[MD5_SIZE];
54	const char *ep;
55	static const char *magic = "$1$";
56
57	/* If the salt starts with the magic string, skip that. */
58	if (!strncmp(salt, magic, strlen(magic)))
59		salt += strlen(magic);
60
61	/* It stops at the first '$', max 8 chars */
62	for (ep = salt; *ep && *ep != '$' && ep < salt + 8; ep++)
63		continue;
64
65	/* get the length of the true salt */
66	sl = ep - salt;
67
68	MD5Init(&ctx);
69
70	/* The password first, since that is what is most unknown */
71	MD5Update(&ctx, (const u_char *)pw, strlen(pw));
72
73	/* Then our magic string */
74	MD5Update(&ctx, (const u_char *)magic, strlen(magic));
75
76	/* Then the raw salt */
77	MD5Update(&ctx, (const u_char *)salt, (u_int)sl);
78
79	/* Then just as many characters of the MD5(pw,salt,pw) */
80	MD5Init(&ctx1);
81	MD5Update(&ctx1, (const u_char *)pw, strlen(pw));
82	MD5Update(&ctx1, (const u_char *)salt, (u_int)sl);
83	MD5Update(&ctx1, (const u_char *)pw, strlen(pw));
84	MD5Final(final, &ctx1);
85	for(pl = (int)strlen(pw); pl > 0; pl -= MD5_SIZE)
86		MD5Update(&ctx, (const u_char *)final,
87		    (u_int)(pl > MD5_SIZE ? MD5_SIZE : pl));
88
89	/* Don't leave anything around in vm they could use. */
90	memset(final, 0, sizeof(final));
91
92	/* Then something really weird... */
93	for (i = strlen(pw); i; i >>= 1)
94		if(i & 1)
95		    MD5Update(&ctx, (const u_char *)final, 1);
96		else
97		    MD5Update(&ctx, (const u_char *)pw, 1);
98
99	/* Now make the output string */
100	buffer = stpcpy(buffer, magic);
101	buffer = stpncpy(buffer, salt, (u_int)sl);
102	*buffer++ = '$';
103
104	MD5Final(final, &ctx);
105
106	/*
107	 * and now, just to make sure things don't run too fast
108	 * On a 60 Mhz Pentium this takes 34 msec, so you would
109	 * need 30 seconds to build a 1000 entry dictionary...
110	 */
111	for(i = 0; i < 1000; i++) {
112		MD5Init(&ctx1);
113		if(i & 1)
114			MD5Update(&ctx1, (const u_char *)pw, strlen(pw));
115		else
116			MD5Update(&ctx1, (const u_char *)final, MD5_SIZE);
117
118		if(i % 3)
119			MD5Update(&ctx1, (const u_char *)salt, (u_int)sl);
120
121		if(i % 7)
122			MD5Update(&ctx1, (const u_char *)pw, strlen(pw));
123
124		if(i & 1)
125			MD5Update(&ctx1, (const u_char *)final, MD5_SIZE);
126		else
127			MD5Update(&ctx1, (const u_char *)pw, strlen(pw));
128		MD5Final(final, &ctx1);
129	}
130
131	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
132	_crypt_to64(buffer, l, 4); buffer += 4;
133	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
134	_crypt_to64(buffer, l, 4); buffer += 4;
135	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
136	_crypt_to64(buffer, l, 4); buffer += 4;
137	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
138	_crypt_to64(buffer, l, 4); buffer += 4;
139	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
140	_crypt_to64(buffer, l, 4); buffer += 4;
141	l = final[11];
142	_crypt_to64(buffer, l, 2); buffer += 2;
143	*buffer = '\0';
144
145	/* Don't leave anything around in vm they could use. */
146	memset(final, 0, sizeof(final));
147
148	return (0);
149}
150