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/* $OpenBSD: md5crypt.c,v 1.9 1997/07/23 20:58:27 kstailey 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
* ----------------------------------------------------------------------------
*
* $FreeBSD: crypt.c,v 1.5 1996/10/14 08:34:02 phk Exp $
*
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: md5crypt.c,v 1.9 1997/07/23 20:58:27 kstailey Exp $";
#endif /* LIBC_SCCS and not lint */
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <md5.h>
static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static void to64 (char *, uint32_t, int);
static void
to64(s, v, n)
char *s;
uint32_t v;
int n;
{
while (--n >= 0) {
*s++ = itoa64[v&0x3f];
v >>= 6;
}
}
/*
* UNIX password
*
* Use MD5 for what it is best at...
*/
char *
md5crypt(pw, salt)
register const char *pw;
register const char *salt;
{
/*
* This string is magic for this algorithm. Having
* it this way, we can get get better later on
*/
static unsigned char *magic = (unsigned char *)"$1$";
static char passwd[120], *p;
static const unsigned char *sp,*ep;
unsigned char final[16];
int sl,pl,i;
MD5_CTX ctx,ctx1;
uint32_t l;
/* Refine the Salt first */
sp = (const unsigned char *)salt;
/* If it starts with the magic string, then skip that */
if(!strncmp((const char *)sp,(const char *)magic,strlen((const char *)magic)))
sp += strlen((const char *)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;
MD5Init(&ctx);
/* The password first, since that is what is most unknown */
MD5Update(&ctx,(const unsigned char *)pw,strlen(pw));
/* Then our magic string */
MD5Update(&ctx,magic,strlen((const char *)magic));
/* Then the raw salt */
MD5Update(&ctx,sp,sl);
/* Then just as many characters of the MD5(pw,salt,pw) */
MD5Init(&ctx1);
MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
MD5Update(&ctx1,sp,sl);
MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
MD5Final(final,&ctx1);
for(pl = strlen(pw); pl > 0; pl -= 16)
MD5Update(&ctx,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 (i = strlen(pw); i ; i >>= 1)
if(i&1)
MD5Update(&ctx, final, 1);
else
MD5Update(&ctx, (const unsigned char *)pw, 1);
/* Now make the output string */
strcpy(passwd,(const char *)magic);
memcpy(passwd+3,sp,sl);
passwd[sl+3]='$';
passwd[sl+4]=0;
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++) {
MD5Init(&ctx1);
if(i & 1)
MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
else
MD5Update(&ctx1,final,16);
if(i % 3)
MD5Update(&ctx1,sp,sl);
if(i % 7)
MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
if(i & 1)
MD5Update(&ctx1,final,16);
else
MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
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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