1/*	$NetBSD: md5crypt.c,v 1.15 2021/10/16 10:53:33 nia Exp $	*/
2
3/*
4 * ----------------------------------------------------------------------------
5 * "THE BEER-WARE LICENSE" (Revision 42):
6 * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
7 * can do whatever you want with this stuff. If we meet some day, and you think
8 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
9 * ----------------------------------------------------------------------------
10 *
11 * from FreeBSD: crypt.c,v 1.5 1996/10/14 08:34:02 phk Exp
12 * via OpenBSD: md5crypt.c,v 1.9 1997/07/23 20:58:27 kstailey Exp
13 *
14 */
15
16#include <sys/cdefs.h>
17#if !defined(lint)
18__RCSID("$NetBSD: md5crypt.c,v 1.15 2021/10/16 10:53:33 nia Exp $");
19#endif /* not lint */
20
21#include <unistd.h>
22#include <stdio.h>
23#include <string.h>
24#include <md5.h>
25
26#include "crypt.h"
27
28#define MD5_MAGIC	"$1$"
29#define MD5_MAGIC_LEN	3
30
31#define	INIT(x)			MD5Init((x))
32#define	UPDATE(x, b, l)		MD5Update((x), (b), (l))
33#define	FINAL(v, x)		MD5Final((v), (x))
34
35
36/*
37 * MD5 password encryption.
38 */
39crypt_private char *
40__md5crypt(const char *pw, const char *salt)
41{
42	static char passwd[120], *p;
43	const char *sp, *ep;
44	unsigned char final[16];
45	unsigned int i, sl, pwl;
46	MD5_CTX	ctx, ctx1;
47	u_int32_t l;
48	int pl;
49
50	pwl = strlen(pw);
51
52	/* Refine the salt first */
53	sp = salt;
54
55	/* If it starts with the magic string, then skip that */
56	if (strncmp(sp, MD5_MAGIC, MD5_MAGIC_LEN) == 0)
57		sp += MD5_MAGIC_LEN;
58
59	/* It stops at the first '$', max 8 chars */
60	for (ep = sp; *ep != '\0' && *ep != '$' && ep < (sp + 8); ep++)
61		continue;
62
63	/* get the length of the true salt */
64	sl = ep - sp;
65
66	INIT(&ctx);
67
68	/* The password first, since that is what is most unknown */
69	UPDATE(&ctx, (const unsigned char *)pw, pwl);
70
71	/* Then our magic string */
72	UPDATE(&ctx, (const unsigned char *)MD5_MAGIC, MD5_MAGIC_LEN);
73
74	/* Then the raw salt */
75	UPDATE(&ctx, (const unsigned char *)sp, sl);
76
77	/* Then just as many characters of the MD5(pw,salt,pw) */
78	INIT(&ctx1);
79	UPDATE(&ctx1, (const unsigned char *)pw, pwl);
80	UPDATE(&ctx1, (const unsigned char *)sp, sl);
81	UPDATE(&ctx1, (const unsigned char *)pw, pwl);
82	FINAL(final, &ctx1);
83
84	for (pl = pwl; pl > 0; pl -= 16)
85		UPDATE(&ctx, final, (unsigned int)(pl > 16 ? 16 : pl));
86
87	/* Don't leave anything around in vm they could use. */
88	memset(final, 0, sizeof(final));
89
90	/* Then something really weird... */
91	for (i = pwl; i != 0; i >>= 1)
92		if ((i & 1) != 0)
93		    UPDATE(&ctx, final, 1);
94		else
95		    UPDATE(&ctx, (const unsigned char *)pw, 1);
96
97	/* Now make the output string */
98	memcpy(passwd, MD5_MAGIC, MD5_MAGIC_LEN);
99	strlcpy(passwd + MD5_MAGIC_LEN, sp, sl + 1);
100	strlcat(passwd, "$", sizeof(passwd));
101
102	FINAL(final, &ctx);
103
104	/* memset(&ctx, 0, sizeof(ctx)); done by MD5Final() */
105
106	/*
107	 * And now, just to make sure things don't run too fast. On a 60 MHz
108	 * Pentium this takes 34 msec, so you would need 30 seconds to build
109	 * a 1000 entry dictionary...
110	 */
111	for (i = 0; i < 1000; i++) {
112		INIT(&ctx1);
113
114		if ((i & 1) != 0)
115			UPDATE(&ctx1, (const unsigned char *)pw, pwl);
116		else
117			UPDATE(&ctx1, final, 16);
118
119		if ((i % 3) != 0)
120			UPDATE(&ctx1, (const unsigned char *)sp, sl);
121
122		if ((i % 7) != 0)
123			UPDATE(&ctx1, (const unsigned char *)pw, pwl);
124
125		if ((i & 1) != 0)
126			UPDATE(&ctx1, final, 16);
127		else
128			UPDATE(&ctx1, (const unsigned char *)pw, pwl);
129
130		FINAL(final, &ctx1);
131	}
132
133	/* memset(&ctx1, 0, sizeof(ctx1)); done by MD5Final() */
134
135	p = passwd + sl + MD5_MAGIC_LEN + 1;
136
137	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; __crypt_to64(p,l,4); p += 4;
138	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; __crypt_to64(p,l,4); p += 4;
139	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; __crypt_to64(p,l,4); p += 4;
140	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; __crypt_to64(p,l,4); p += 4;
141	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; __crypt_to64(p,l,4); p += 4;
142	l =		       final[11]		; __crypt_to64(p,l,2); p += 2;
143	*p = '\0';
144
145	/* Don't leave anything around in vm they could use. */
146	explicit_memset(final, 0, sizeof(final));
147	return (passwd);
148}
149