crypt-md5.c revision 51462 
1/*
2 * ----------------------------------------------------------------------------
3 * "THE BEER-WARE LICENSE" (Revision 42):
4 * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you think
6 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
7 * ----------------------------------------------------------------------------
8 *
9 * $FreeBSD: head/lib/libcrypt/crypt-md5.c 51462 1999-09-20 12:45:49Z markm $
10 *
11 */
12
13#if defined(LIBC_SCCS) && !defined(lint)
14static const char rcsid[] = "$FreeBSD: head/lib/libcrypt/crypt-md5.c 51462 1999-09-20 12:45:49Z markm $";
15#endif /* LIBC_SCCS and not lint */
16
17#include <unistd.h>
18#include <stdio.h>
19#include <string.h>
20#include <md5.h>
21#include "crypt.h"
22
23/*
24 * UNIX password
25 */
26
27char *
28crypt_md5(pw, salt)
29	const char *pw;
30	const char *salt;
31{
32	static char	*magic = "$1$";	/*
33					 * This string is magic for
34					 * this algorithm.  Having
35					 * it this way, we can get
36					 * get better later on
37					 */
38	static char     passwd[120], *p;
39	static const char *sp,*ep;
40	unsigned char	final[MD5_SIZE];
41	int sl,pl,i;
42	MD5_CTX	ctx,ctx1;
43	unsigned long l;
44
45	/* Refine the Salt first */
46	sp = salt;
47
48	/* If it starts with the magic string, then skip that */
49	if(!strncmp(sp,magic,strlen(magic)))
50		sp += strlen(magic);
51
52	/* It stops at the first '$', max 8 chars */
53	for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
54		continue;
55
56	/* get the length of the true salt */
57	sl = ep - sp;
58
59	MD5Init(&ctx);
60
61	/* The password first, since that is what is most unknown */
62	MD5Update(&ctx,pw,strlen(pw));
63
64	/* Then our magic string */
65	MD5Update(&ctx,magic,strlen(magic));
66
67	/* Then the raw salt */
68	MD5Update(&ctx,sp,sl);
69
70	/* Then just as many characters of the MD5(pw,salt,pw) */
71	MD5Init(&ctx1);
72	MD5Update(&ctx1,pw,strlen(pw));
73	MD5Update(&ctx1,sp,sl);
74	MD5Update(&ctx1,pw,strlen(pw));
75	MD5Final(final,&ctx1);
76	for(pl = strlen(pw); pl > 0; pl -= MD5_SIZE)
77		MD5Update(&ctx,final,pl>MD5_SIZE ? MD5_SIZE : pl);
78
79	/* Don't leave anything around in vm they could use. */
80	memset(final,0,sizeof final);
81
82	/* Then something really weird... */
83	for (i = strlen(pw); i ; i >>= 1)
84		if(i&1)
85		    MD5Update(&ctx, final, 1);
86		else
87		    MD5Update(&ctx, pw, 1);
88
89	/* Now make the output string */
90	strcpy(passwd,magic);
91	strncat(passwd,sp,sl);
92	strcat(passwd,"$");
93
94	MD5Final(final,&ctx);
95
96	/*
97	 * and now, just to make sure things don't run too fast
98	 * On a 60 Mhz Pentium this takes 34 msec, so you would
99	 * need 30 seconds to build a 1000 entry dictionary...
100	 */
101	for(i=0;i<1000;i++) {
102		MD5Init(&ctx1);
103		if(i & 1)
104			MD5Update(&ctx1,pw,strlen(pw));
105		else
106			MD5Update(&ctx1,final,MD5_SIZE);
107
108		if(i % 3)
109			MD5Update(&ctx1,sp,sl);
110
111		if(i % 7)
112			MD5Update(&ctx1,pw,strlen(pw));
113
114		if(i & 1)
115			MD5Update(&ctx1,final,MD5_SIZE);
116		else
117			MD5Update(&ctx1,pw,strlen(pw));
118		MD5Final(final,&ctx1);
119	}
120
121	p = passwd + strlen(passwd);
122
123	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
124	_crypt_to64(p,l,4); p += 4;
125	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
126	_crypt_to64(p,l,4); p += 4;
127	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
128	_crypt_to64(p,l,4); p += 4;
129	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
130	_crypt_to64(p,l,4); p += 4;
131	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
132	_crypt_to64(p,l,4); p += 4;
133	l =                    final[11]                ;
134	_crypt_to64(p,l,2); p += 2;
135	*p = '\0';
136
137	/* Don't leave anything around in vm they could use. */
138	memset(final,0,sizeof final);
139
140	return passwd;
141}
142
143