source: trunk/sys/dietlibc/md5crypt.c @ 67

/*      $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;
}