1 /*
2 * $Id$
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 * Origin: Id: crypt.c,v 1.3 1995/05/30 05:42:22 rgrimes Exp
12 *
13 */
14
15 #include <string.h>
16 #include <stdlib.h>
17 #include "md5.h"
18 #include "pam_inline.h"
19
20 static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
21 "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
22
23 static void to64(char *s, unsigned long v, int n)
24 {
25 while (--n >= 0) {
26 *s++ = itoa64[v & 0x3f];
27 v >>= 6;
28 }
29 }
30
31 /*
32 * UNIX password
33 *
34 * Use MD5 for what it is best at...
35 */
36
37 char *MD5Name(crypt_md5)(const char *pw, const char *salt)
38 {
39 const char *magic = "$1$";
40 /* This string is magic for this algorithm. Having
41 * it this way, we can get get better later on */
42 char *passwd, *p;
43 const char *sp, *ep;
44 unsigned char final[16];
45 int sl, pl, i, j;
46 MD5_CTX ctx, ctx1;
47 unsigned long l;
48
49 /* Refine the Salt first */
50 sp = salt;
51
52 /* TODO: now that we're using malloc'ed memory, get rid of the
53 strange constant buffer size. */
54 passwd = malloc(120);
55 if (passwd == NULL)
56 return NULL;
57
58 /* If it starts with the magic string, then skip that */
59 if ((ep = pam_str_skip_prefix_len(sp, magic, strlen(magic))) != NULL)
60 sp = ep;
61
62 /* It stops at the first '$', max 8 chars */
63 for (ep = sp; *ep && *ep != '$' && ep < (sp + 8); ep++)
64 continue;
65
66 /* get the length of the true salt */
67 sl = ep - sp;
68
69 MD5Name(MD5Init)(&ctx);
70
71 /* The password first, since that is what is most unknown */
72 MD5Name(MD5Update)(&ctx,(unsigned const char *)pw,strlen(pw));
73
74 /* Then our magic string */
75 MD5Name(MD5Update)(&ctx,(unsigned const char *)magic,strlen(magic));
76
77 /* Then the raw salt */
78 MD5Name(MD5Update)(&ctx,(unsigned const char *)sp,sl);
79
80 /* Then just as many characters of the MD5(pw,salt,pw) */
81 MD5Name(MD5Init)(&ctx1);
82 MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
83 MD5Name(MD5Update)(&ctx1,(unsigned const char *)sp,sl);
84 MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
85 MD5Name(MD5Final)(final,&ctx1);
86 for (pl = strlen(pw); pl > 0; pl -= 16)
87 MD5Name(MD5Update)(&ctx,(unsigned const char *)final,pl>16 ? 16 : pl);
88
89 /* Don't leave anything around in vm they could use. */
90 pam_overwrite_array(final);
91
92 /* Then something really weird... */
93 for (j = 0, i = strlen(pw); i; i >>= 1)
94 if (i & 1)
95 MD5Name(MD5Update)(&ctx, (unsigned const char *)final+j, 1);
96 else
97 MD5Name(MD5Update)(&ctx, (unsigned const char *)pw+j, 1);
98
99 /* Now make the output string */
100 strcpy(passwd, magic);
101 strncat(passwd, sp, sl);
102 strcat(passwd, "$");
103
104 MD5Name(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 MD5Name(MD5Init)(&ctx1);
113 if (i & 1)
114 MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
115 else
116 MD5Name(MD5Update)(&ctx1,(unsigned const char *)final,16);
117
118 if (i % 3)
119 MD5Name(MD5Update)(&ctx1,(unsigned const char *)sp,sl);
120
121 if (i % 7)
122 MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
123
124 if (i & 1)
125 MD5Name(MD5Update)(&ctx1,(unsigned const char *)final,16);
126 else
127 MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
128 MD5Name(MD5Final)(final,&ctx1);
129 }
130
131 p = passwd + strlen(passwd);
132
133 l = (final[0] << 16) | (final[6] << 8) | final[12];
134 to64(p, l, 4);
135 p += 4;
136 l = (final[1] << 16) | (final[7] << 8) | final[13];
137 to64(p, l, 4);
138 p += 4;
139 l = (final[2] << 16) | (final[8] << 8) | final[14];
140 to64(p, l, 4);
141 p += 4;
142 l = (final[3] << 16) | (final[9] << 8) | final[15];
143 to64(p, l, 4);
144 p += 4;
145 l = (final[4] << 16) | (final[10] << 8) | final[5];
146 to64(p, l, 4);
147 p += 4;
148 l = final[11];
149 to64(p, l, 2);
150 p += 2;
151 *p = '\0';
152
153 /* Don't leave anything around in vm they could use. */
154 pam_overwrite_array(final);
155
156 return passwd;
157 }