source: trunk/third/openssh/md5crypt.c @ 22570

/*
 * ----------------------------------------------------------------------------
 * "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
 * ----------------------------------------------------------------------------
 */

#include "includes.h"

#if defined(HAVE_MD5_PASSWORDS) && !defined(HAVE_MD5_CRYPT)
#include <openssl/md5.h>

RCSID("$Id: md5crypt.c,v 1.1.1.2 2006-11-30 21:18:48 ghudson Exp $");

/* 0 ... 63 => ascii - 64 */
static unsigned char itoa64[] =
    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static char *magic = "$1$";

static char *
to64(unsigned long v, int n)
{
        static char buf[5];
        char *s = buf;

        if (n > 4)
                return (NULL);

        memset(buf, '\0', sizeof(buf));
        while (--n >= 0) {
                *s++ = itoa64[v&0x3f];
                v >>= 6;
        }

        return (buf);
}

int
is_md5_salt(const char *salt)
{
        return (strncmp(salt, magic, strlen(magic)) == 0);
}

char *
md5_crypt(const char *pw, const char *salt)
{
        static char passwd[120], salt_copy[9], *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)) == 0)
                sp += strlen(magic);

        /* It stops at the first '$', max 8 chars */
        for (ep = sp; *ep != '$'; ep++) {
                if (*ep == '\0' || ep >= (sp + 8))
                        return (NULL);
        }

        /* get the length of the true salt */
        sl = ep - sp;

        /* Stash the salt */
        memcpy(salt_copy, sp, sl);
        salt_copy[sl] = '\0';

        MD5_Init(&ctx);

        /* The password first, since that is what is most unknown */
        MD5_Update(&ctx, pw, strlen(pw));

        /* Then our magic string */
        MD5_Update(&ctx, magic, strlen(magic));

        /* 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, pw, strlen(pw));
        MD5_Update(&ctx1, sp, sl);
        MD5_Update(&ctx1, pw, strlen(pw));
        MD5_Final(final, &ctx1);

        for(pl = strlen(pw); pl > 0; pl -= 16)
                MD5_Update(&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 (j = 0, i = strlen(pw); i != 0; i >>= 1)
                if (i & 1)
                        MD5_Update(&ctx, final + j, 1);
                else
                        MD5_Update(&ctx, pw + j, 1);

        /* Now make the output string */
        snprintf(passwd, sizeof(passwd), "%s%s$", magic, salt_copy);

        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, pw, strlen(pw));
                else
                        MD5_Update(&ctx1, final, 16);

                if (i % 3)
                        MD5_Update(&ctx1, sp, sl);

                if (i % 7)
                        MD5_Update(&ctx1, pw, strlen(pw));

                if (i & 1)
                        MD5_Update(&ctx1, final, 16);
                else
                        MD5_Update(&ctx1, pw, strlen(pw));

                MD5_Final(final, &ctx1);
        }

        p = passwd + strlen(passwd);

        l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
        strlcat(passwd, to64(l, 4), sizeof(passwd));
        l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
        strlcat(passwd, to64(l, 4), sizeof(passwd));
        l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
        strlcat(passwd, to64(l, 4), sizeof(passwd));
        l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
        strlcat(passwd, to64(l, 4), sizeof(passwd));
        l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
        strlcat(passwd, to64(l, 4), sizeof(passwd));
        l =                    final[11]                ;
        strlcat(passwd, to64(l, 2), sizeof(passwd));

        /* Don't leave anything around in vm they could use. */
        memset(final, 0, sizeof(final));
        memset(salt_copy, 0, sizeof(salt_copy));
        memset(&ctx, 0, sizeof(ctx));
        memset(&ctx1, 0, sizeof(ctx1));
        (void)to64(0, 4);

        return (passwd);
}

#endif /* defined(HAVE_MD5_PASSWORDS) && !defined(HAVE_MD5_CRYPT) */