/* One way encryption based on MD5 sum.
   Copyright (C) 1996, 1997, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/* warmenhoven took this file and made it work with the md5.[ch] we
 * already had. isn't that lovely. people should just use linux or
 * freebsd, crypt works properly on those systems. i hate solaris */

#include <string.h>
#include <stdlib.h>
#include <malloc.h>

#include "md5.h"

/* Added by Devdas */
/* Replace g_realloc and g_free by realloc and free */

#define MIN(x,y) ((x) < (y))?(x):(y)
#define MAX(x,y) ((x) > (y))?(x):(y)



/* Define our magic string to mark salt for MD5 "encryption"
   replacement.  This is meant to be the same as for other MD5 based
   encryption implementations.  */
static const char md5_salt_prefix[] = "$1$";

/* Table with characters for base64 transformation.  */
static const char b64t[64] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";


char *yahoo_crypt(char *key, char *salt)
{
char *buffer = NULL;
int buflen = 0;
int needed = 3 + strlen (salt) + 1 + 26 + 1;
md5_byte_t alt_result[16];
md5_state_t ctx;
md5_state_t alt_ctx;
size_t salt_len;
size_t key_len;
size_t cnt;
char *cp;
if (buflen < needed) {
buflen = needed;
if ((buffer = realloc(buffer, buflen)) == NULL)
return NULL;
}
/* Find beginning of salt string.  The prefix should normally always
   be present.  Just in case it is not.  */
if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0)
/* Skip salt prefix.  */
salt += sizeof (md5_salt_prefix) - 1;
salt_len = MIN (strcspn (salt, "$"), 8);
key_len = strlen (key);
/* Prepare for the real work.  */
md5_init(&ctx);
/* Add the key string.  */
md5_append(&ctx, (md5_byte_t *)key, key_len);
/* Because the SALT argument need not always have the salt prefix we
   add it separately.  */
md5_append(&ctx, (md5_byte_t *)md5_salt_prefix, sizeof (md5_salt_prefix) - 1);
/* The last part is the salt string.  This must be at most 8
   characters and it ends at the first `$' character (for
   compatibility which existing solutions).  */
md5_append(&ctx, (md5_byte_t *)salt, salt_len);
/* Compute alternate MD5 sum with input KEY, SALT, and KEY.  The
   final result will be added to the first context.  */
md5_init(&alt_ctx);
/* Add key.  */
md5_append(&alt_ctx, (md5_byte_t *)key, key_len);
/* Add salt.  */
md5_append(&alt_ctx, (md5_byte_t *)salt, salt_len);
/* Add key again.  */
md5_append(&alt_ctx, (md5_byte_t *)key, key_len);
/* Now get result of this (16 bytes) and add it to the other
   context.  */
md5_finish(&alt_ctx, alt_result);
/* Add for any character in the key one byte of the alternate sum.  */
for (cnt = key_len; cnt > 16; cnt -= 16)
md5_append(&ctx, alt_result, 16);
md5_append(&ctx, alt_result, cnt);
/* For the following code we need a NUL byte.  */
alt_result[0] = '\0';
/* The original implementation now does something weird: for every 1
   bit in the key the first 0 is added to the buffer, for every 0
   bit the first character of the key.  This does not seem to be
   what was intended but we have to follow this to be compatible.  */
for (cnt = key_len; cnt > 0; cnt >>= 1)
md5_append(&ctx, (cnt & 1) != 0 ? alt_result : (md5_byte_t *)key, 1);
/* Create intermediate result.  */
md5_finish(&ctx, alt_result);
/* Now comes another weirdness.  In fear of password crackers here
   comes a quite long loop which just processes the output of the
   previous round again.  We cannot ignore this here.  */
for (cnt = 0; cnt < 1000; ++cnt) {
/* New context.  */
md5_init(&ctx);
/* Add key or last result.  */
if ((cnt & 1) != 0)
md5_append(&ctx, (md5_byte_t *)key, key_len);
else
md5_append(&ctx, alt_result, 16);
/* Add salt for numbers not divisible by 3.  */
if (cnt % 3 != 0)
md5_append(&ctx, (md5_byte_t *)salt, salt_len);
/* Add key for numbers not divisible by 7.  */
if (cnt % 7 != 0)
md5_append(&ctx, (md5_byte_t *)key, key_len);
/* Add key or last result.  */
if ((cnt & 1) != 0)
md5_append(&ctx, alt_result, 16);
else
md5_append(&ctx, (md5_byte_t *)key, key_len);
/* Create intermediate result.  */
md5_finish(&ctx, alt_result);
}
/* Now we can construct the result string.  It consists of three
   parts.  */
strncpy(buffer, md5_salt_prefix, MAX (0, buflen));
cp = buffer + strlen(buffer);
buflen -= sizeof (md5_salt_prefix);
strncpy(cp, salt, MIN ((size_t) buflen, salt_len));
cp = cp + strlen(cp);
buflen -= MIN ((size_t) buflen, salt_len);
if (buflen > 0) {
*cp++ = '$';
--buflen;
}
#define b64_from_24bit(B2, B1, B0, N) \
do { \
unsigned int w = ((B2) << 16) | ((B1) << 8) | (B0); \
int n = (N); \
while (n-- > 0 && buflen > 0) { \
*cp++ = b64t[w & 0x3f]; \
--buflen; \
w >>= 6; \
}\
} while (0)
b64_from_24bit (alt_result[0], alt_result[6], alt_result[12], 4);
b64_from_24bit (alt_result[1], alt_result[7], alt_result[13], 4);
b64_from_24bit (alt_result[2], alt_result[8], alt_result[14], 4);
b64_from_24bit (alt_result[3], alt_result[9], alt_result[15], 4);
b64_from_24bit (alt_result[4], alt_result[10], alt_result[5], 4);
b64_from_24bit (0, 0, alt_result[11], 2);
if (buflen <= 0) {
free(buffer);
} else
*cp = '\0';/* Terminate the string.  */
/* Clear the buffer for the intermediate result so that people
   attaching to processes or reading core dumps cannot get any
   information.  We do it in this way to clear correct_words[]
   inside the MD5 implementation as well.  */
md5_init(&ctx);
md5_finish(&ctx, alt_result);
memset (&ctx, '\0', sizeof (ctx));
memset (&alt_ctx, '\0', sizeof (alt_ctx));
return buffer;
}
