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/*
* chap-md5.c - New CHAP/MD5 implementation.
*
* Copyright (c) 2003 Paul Mackerras. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. The name(s) of the authors of this software must not be used to
* endorse or promote products derived from this software without
* prior written permission.
*
* 3. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Paul Mackerras
* <paulus@samba.org>".
*
* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#define RCSID "$Id: chap-md5.c,v 1.4 2004/11/09 22:39:25 paulus Exp $"
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <string.h>
#include "pppd.h"
#include "chap-new.h"
#include "chap-md5.h"
#include "magic.h"
#include "md5.h"
#define MD5_HASH_SIZE 16
#define MD5_MIN_CHALLENGE 16
#define MD5_MAX_CHALLENGE 24
static void
chap_md5_generate_challenge(unsigned char *cp)
{
int clen;
clen = (int)(drand48() * (MD5_MAX_CHALLENGE - MD5_MIN_CHALLENGE))
+ MD5_MIN_CHALLENGE;
*cp++ = clen;
random_bytes(cp, clen);
}
static int
chap_md5_verify_response(int id, char *name,
unsigned char *secret, int secret_len,
unsigned char *challenge, unsigned char *response,
char *message, int message_space)
{
MD5_CTX ctx;
unsigned char idbyte = id;
unsigned char hash[MD5_HASH_SIZE];
int challenge_len, response_len;
challenge_len = *challenge++;
response_len = *response++;
if (response_len == MD5_HASH_SIZE) {
/* Generate hash of ID, secret, challenge */
MD5_Init(&ctx);
MD5_Update(&ctx, &idbyte, 1);
MD5_Update(&ctx, secret, secret_len);
MD5_Update(&ctx, challenge, challenge_len);
MD5_Final(hash, &ctx);
/* Test if our hash matches the peer's response */
if (memcmp(hash, response, MD5_HASH_SIZE) == 0) {
slprintf(message, message_space, "Access granted");
return 1;
}
}
slprintf(message, message_space, "Access denied");
return 0;
}
static void
chap_md5_make_response(unsigned char *response, int id, char *our_name,
unsigned char *challenge, char *secret, int secret_len,
unsigned char *private)
{
MD5_CTX ctx;
unsigned char idbyte = id;
int challenge_len = *challenge++;
MD5_Init(&ctx);
MD5_Update(&ctx, &idbyte, 1);
MD5_Update(&ctx, (u_char *)secret, secret_len);
MD5_Update(&ctx, challenge, challenge_len);
MD5_Final(&response[1], &ctx);
response[0] = MD5_HASH_SIZE;
}
static struct chap_digest_type md5_digest = {
CHAP_MD5, /* code */
chap_md5_generate_challenge,
chap_md5_verify_response,
chap_md5_make_response,
NULL, /* check_success */
NULL, /* handle_failure */
};
void
chap_md5_init(void)
{
chap_register_digest(&md5_digest);
}
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