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/* $OpenBSD: md5crypt.c,v 1.9 1997/07/23 20:58:27 kstailey Exp $ */
/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <[email protected]> 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 "md5.h"
static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static void to64(unsigned 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...
*/
#define R(F,P,Q,R) to64(p, (F[P]<<16) | (F[Q]<<8) | F[R], 4); p += 4
#define magic (unsigned char *)"$1$"
char *md5crypt(const char *pw, const char *salt) /*EXTRACT_INCL*/
{
static char passwd[40];
const unsigned char *sp,*ep;
unsigned char final[16], *p = (unsigned char *)pw;
int sl,i,pw_len = str_len(pw);
MD5_CTX ctx,ctx1;
/* Refine the Salt first */
sp = (const unsigned char *)salt;
/* If it starts with the magic string, then skip that */
if (!byte_diff(sp,3,magic))
sp += 3;
/* 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;
MD5_Init(&ctx);
/* The password first, since that is what is most unknown */
MD5_Update(&ctx,p,pw_len);
/* Then our magic string */
MD5_Update(&ctx,magic,3);
/* Then the raw salt */
MD5_Update(&ctx,sp,sl);
/* Then just as many characters of the MD5(pw,salt,pw) */
MD5_Init(&ctx1);
MD5_Update(&ctx1,p,pw_len);
MD5_Update(&ctx1,sp,sl);
MD5_Update(&ctx1,p,pw_len);
MD5_Final(final,&ctx1);
for (i = pw_len; i > 0; i -= 16)
MD5_Update(&ctx,final,(i>16) ? 16 : i);
/* Don't leave anything around in vm they could use. */
byte_zero(final,sizeof(final));
/* Then something really weird... */
for (i = pw_len; i ; i >>= 1)
if(i&1)
MD5_Update(&ctx, final, 1);
else
MD5_Update(&ctx, p, 1);
MD5_Final(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++) {
MD5_Init(&ctx1);
if(i & 1)
MD5_Update(&ctx1,p,pw_len);
else
MD5_Update(&ctx1,final,16);
if(i % 3)
MD5_Update(&ctx1,sp,sl);
if(i % 7)
MD5_Update(&ctx1,p,pw_len);
if(i & 1)
MD5_Update(&ctx1,final,16);
else
MD5_Update(&ctx1,p,pw_len);
MD5_Final(final,&ctx1);
}
/* Now make the output string */
p = (unsigned char *)passwd + 3 + sl;
byte_copy(passwd, 3, magic);
byte_copy(passwd+3, sl, sp);
*p++ = '$';
R(final, 0, 6,12);
R(final, 1, 7,13);
R(final, 2, 8,14);
R(final, 3, 9,15);
R(final, 4,10, 5);
to64(p,final[11],2);
p[2] = 0;
/* Don't leave anything around in vm they could use. */
byte_zero(final,sizeof(final));
pw_len = 0;
return passwd;
}
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