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 * $Id$
10 *
11 */
12
13#if defined(LIBC_SCCS) && !defined(lint)
14static char rcsid[] = "$Header: /home/ncvs/src/lib/libcrypt/crypt.c,v 1.6 1997/01/14 06:09:00 jkh Exp $";
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 <string.h>
22
23static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
24 "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
25
26static void to64 __P((char *, unsigned long, int));
27
28static void
29to64(s, v, n)
30 char *s;
31 unsigned long v;
32 int n;
33{
34static void to64 __P((char *, unsigned long, int));
35
36 while (--n >= 0) {
37 *s++ = itoa64[v&0x3f];
38 v >>= 6;
39 }
40}
41
42/*
43 * UNIX password
44 *
45 * Use MD5 for what it is best at...
46 */
47
48char *
49crypt(pw, salt)
50 register const char *pw;
51 register const char *salt;
52{
53 static char *magic = "$1$"; /*
54 * This string is magic for
55 * this algorithm. Having
56 * it this way, we can get
57 * get better later on
58 */
59 static char passwd[120], *p;
60 static const char *sp,*ep;
61 unsigned char final[16];
62 int sl,pl,i,j;
63 MD5_CTX ctx,ctx1;
64 unsigned long l;
65
66 /* Refine the Salt first */
67 sp = salt;
68
69 /* If it starts with the magic string, then skip that */
70 if(!strncmp(sp,magic,strlen(magic)))
71 sp += strlen(magic);
72
73 /* It stops at the first '$', max 8 chars */
74 for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
75 continue;
76
77 /* get the length of the true salt */
78 sl = ep - sp;
79
80 MD5Init(&ctx);
81
82 /* The password first, since that is what is most unknown */
83 MD5Update(&ctx,pw,strlen(pw));
84
85 /* Then our magic string */
86 MD5Update(&ctx,magic,strlen(magic));
87
88 /* Then the raw salt */
89 MD5Update(&ctx,sp,sl);
90
91 /* Then just as many characters of the MD5(pw,salt,pw) */
92 MD5Init(&ctx1);
93 MD5Update(&ctx1,pw,strlen(pw));
94 MD5Update(&ctx1,sp,sl);
95 MD5Update(&ctx1,pw,strlen(pw));
96 MD5Final(final,&ctx1);
97 for(pl = strlen(pw); pl > 0; pl -= 16)
98 MD5Update(&ctx,final,pl>16 ? 16 : pl);
99
100 /* Don't leave anything around in vm they could use. */
101 memset(final,0,sizeof final);
102
103 /* Then something really weird... */
104 for (i = strlen(pw); i ; i >>= 1)
105 if(i&1)
106 MD5Update(&ctx, final, 1);
107 else
108 MD5Update(&ctx, pw, 1);
109
110 /* Now make the output string */
111 strcpy(passwd,magic);
112 strncat(passwd,sp,sl);
113 strcat(passwd,"$");
114
115 MD5Final(final,&ctx);
116
117 /*
118 * and now, just to make sure things don't run too fast
119 * On a 60 Mhz Pentium this takes 34 msec, so you would
120 * need 30 seconds to build a 1000 entry dictionary...
121 */
122 for(i=0;i<1000;i++) {
123 MD5Init(&ctx1);
124 if(i & 1)
125 MD5Update(&ctx1,pw,strlen(pw));
126 else
127 MD5Update(&ctx1,final,16);
128
129 if(i % 3)
130 MD5Update(&ctx1,sp,sl);
131
132 if(i % 7)
133 MD5Update(&ctx1,pw,strlen(pw));
134
135 if(i & 1)
136 MD5Update(&ctx1,final,16);
137 else
138 MD5Update(&ctx1,pw,strlen(pw));
139 MD5Final(final,&ctx1);
140 }
141
142 p = passwd + strlen(passwd);
143
144 l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; to64(p,l,4); p += 4;
145 l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; to64(p,l,4); p += 4;
146 l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; to64(p,l,4); p += 4;
147 l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; to64(p,l,4); p += 4;
148 l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; to64(p,l,4); p += 4;
149 l = final[11] ; to64(p,l,2); p += 2;
150 *p = '\0';
151
152 /* Don't leave anything around in vm they could use. */
153 memset(final,0,sizeof final);
154
155 return passwd;
156}
157