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/*
* $Id: md5_crypt.c,v 1.1 2002/05/11 14:42:35 cpbotha Exp $
*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <phk@login.dknet.dk> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*
* Origin: Id: crypt.c,v 1.3 1995/05/30 05:42:22 rgrimes Exp
*
*/
#include <string.h>
#include "md5.h"
static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static void to64(char *s, unsigned long v, int n)
{
while (--n >= 0) {
*s++ = itoa64[v & 0x3f];
v >>= 6;
}
}
/*
* UNIX password
*
* Use MD5 for what it is best at...
*/
char *MD5Name(crypt_md5)(const char *pw, const char *salt)
{
const char *magic = "$1$";
/* This string is magic for this algorithm. Having
* it this way, we can get get better later on */
static char passwd[120], *p;
static const char *sp, *ep;
unsigned char final[16];
int sl, pl, i, j;
MD5_CTX ctx, ctx1;
unsigned long l;
/* Refine the Salt first */
sp = salt;
/* If it starts with the magic string, then skip that */
if (!strncmp(sp, magic, strlen(magic)))
sp += strlen(magic);
/* It stops at the first '$', max 8 chars */
for (ep = sp; *ep && *ep != '$' && ep < (sp + 8); ep++)
continue;
/* get the length of the true salt */
sl = ep - sp;
MD5Name(MD5Init)(&ctx);
/* The password first, since that is what is most unknown */
MD5Name(MD5Update)(&ctx,(unsigned const char *)pw,strlen(pw));
/* Then our magic string */
MD5Name(MD5Update)(&ctx,(unsigned const char *)magic,strlen(magic));
/* Then the raw salt */
MD5Name(MD5Update)(&ctx,(unsigned const char *)sp,sl);
/* Then just as many characters of the MD5(pw,salt,pw) */
MD5Name(MD5Init)(&ctx1);
MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
MD5Name(MD5Update)(&ctx1,(unsigned const char *)sp,sl);
MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
MD5Name(MD5Final)(final,&ctx1);
for (pl = strlen(pw); pl > 0; pl -= 16)
MD5Name(MD5Update)(&ctx,(unsigned const char *)final,pl>16 ? 16 : pl);
/* Don't leave anything around in vm they could use. */
memset(final, 0, sizeof final);
/* Then something really weird... */
for (j = 0, i = strlen(pw); i; i >>= 1)
if (i & 1)
MD5Name(MD5Update)(&ctx, (unsigned const char *)final+j, 1);
else
MD5Name(MD5Update)(&ctx, (unsigned const char *)pw+j, 1);
/* Now make the output string */
strcpy(passwd, magic);
strncat(passwd, sp, sl);
strcat(passwd, "$");
MD5Name(MD5Final)(final,&ctx);
/*
* and now, just to make sure things don't run too fast
* On a 60 Mhz Pentium this takes 34 msec, so you would
* need 30 seconds to build a 1000 entry dictionary...
*/
for (i = 0; i < 1000; i++) {
MD5Name(MD5Init)(&ctx1);
if (i & 1)
MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
else
MD5Name(MD5Update)(&ctx1,(unsigned const char *)final,16);
if (i % 3)
MD5Name(MD5Update)(&ctx1,(unsigned const char *)sp,sl);
if (i % 7)
MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
if (i & 1)
MD5Name(MD5Update)(&ctx1,(unsigned const char *)final,16);
else
MD5Name(MD5Update)(&ctx1,(unsigned const char *)pw,strlen(pw));
MD5Name(MD5Final)(final,&ctx1);
}
p = passwd + strlen(passwd);
l = (final[0] << 16) | (final[6] << 8) | final[12];
to64(p, l, 4);
p += 4;
l = (final[1] << 16) | (final[7] << 8) | final[13];
to64(p, l, 4);
p += 4;
l = (final[2] << 16) | (final[8] << 8) | final[14];
to64(p, l, 4);
p += 4;
l = (final[3] << 16) | (final[9] << 8) | final[15];
to64(p, l, 4);
p += 4;
l = (final[4] << 16) | (final[10] << 8) | final[5];
to64(p, l, 4);
p += 4;
l = final[11];
to64(p, l, 2);
p += 2;
*p = '\0';
/* Don't leave anything around in vm they could use. */
memset(final, 0, sizeof final);
return passwd;
}
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