Sylpheed

/*

 * LibSylph -- E-Mail client library

 * Copyright (C) 1999-2006 Hiroyuki Yamamoto

 *

 * This 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.

 *

 * This 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 this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#ifdef HAVE_CONFIG_H

#  include "config.h"

#endif

#include <glib.h>

#include <string.h>

#include "md5.h"

#include "md5_hmac.h"

/*

** Function: md5_hmac_get

** taken from the file rfc2104.txt

** originally written by Martin Schaaf <mascha@ma-scha.de>

** rewritten by Hiroyuki Yamamoto <hiro-y@kcn.ne.jp>

*/

static SMD5*

md5_hmac_get(const guchar *text, gint text_len,

             const guchar *key, gint key_len)

{

        SMD5 *md5;

        guchar k_ipad[64];    /* inner padding -

                               * key XORd with ipad

                               */

        guchar k_opad[64];    /* outer padding -

                               * key XORd with opad

                               */

        guchar digest[S_GNET_MD5_HASH_LENGTH];

        gint i;

        /* start out by storing key in pads */

        memset(k_ipad, 0, sizeof k_ipad);

        memset(k_opad, 0, sizeof k_opad);

        if (key_len > 64) {

                /* if key is longer than 64 bytes reset it to key=MD5(key) */

                SMD5 *tmd5;

                tmd5 = s_gnet_md5_new(key, key_len);

                memcpy(k_ipad, s_gnet_md5_get_digest(tmd5),

                       S_GNET_MD5_HASH_LENGTH);

                memcpy(k_opad, s_gnet_md5_get_digest(tmd5),

                       S_GNET_MD5_HASH_LENGTH);

                s_gnet_md5_delete(tmd5);

        } else {

                memcpy(k_ipad, key, key_len);

                memcpy(k_opad, key, key_len);

        }

        /*

         * the HMAC_MD5 transform looks like:

         *

         * MD5(K XOR opad, MD5(K XOR ipad, text))

         *

         * where K is an n byte key

         * ipad is the byte 0x36 repeated 64 times

         * opad is the byte 0x5c repeated 64 times

         * and text is the data being protected

         */

        /* XOR key with ipad and opad values */

        for (i = 0; i < 64; i++) {

                k_ipad[i] ^= 0x36;

                k_opad[i] ^= 0x5c;

        }

        /*

         * perform inner MD5

         */

        md5 = s_gnet_md5_new_incremental();        /* init context for 1st

                                                 * pass */

        s_gnet_md5_update(md5, k_ipad, 64);        /* start with inner pad */

        s_gnet_md5_update(md5, text, text_len);        /* then text of datagram */

        s_gnet_md5_final(md5);                        /* finish up 1st pass */

        memcpy(digest, s_gnet_md5_get_digest(md5), S_GNET_MD5_HASH_LENGTH);

        s_gnet_md5_delete(md5);

        /*

         * perform outer MD5

         */

        md5 = s_gnet_md5_new_incremental();        /* init context for 2nd

                                                 * pass */

        s_gnet_md5_update(md5, k_opad, 64);        /* start with outer pad */

        s_gnet_md5_update(md5, digest, 16);        /* then results of 1st

                                                 * hash */

        s_gnet_md5_final(md5);                        /* finish up 2nd pass */

        return md5;

}

void

md5_hmac(guchar *digest,

         const guchar *text, gint text_len,

         const guchar *key, gint key_len)

{

        SMD5 *md5;

        md5 = md5_hmac_get(text, text_len, key, key_len);

        memcpy(digest, s_gnet_md5_get_digest(md5), S_GNET_MD5_HASH_LENGTH);

        s_gnet_md5_delete(md5);

}

void

md5_hex_hmac(gchar *hexdigest,

             const guchar *text, gint text_len,

             const guchar *key, gint key_len)

{

        SMD5 *md5;

        md5 = md5_hmac_get(text, text_len, key, key_len);

        s_gnet_md5_copy_string(md5, hexdigest);

        hexdigest[S_GNET_MD5_HASH_LENGTH * 2] = '\0';

        s_gnet_md5_delete(md5);

}