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/* $OpenBSD: kexecdh.c,v 1.3 2010/09/22 05:01:29 djm Exp $ */
/*
* Copyright (c) 2001 Markus Friedl. All rights reserved.
* Copyright (c) 2010 Damien Miller. 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. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <signal.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/ec.h>
#include <openssl/ecdh.h>
#include "buffer.h"
#include "ssh2.h"
#include "key.h"
#include "cipher.h"
#include "kex.h"
#include "log.h"
int
kex_ecdh_name_to_nid(const char *kexname)
{
if (strlen(kexname) < sizeof(KEX_ECDH_SHA2_STEM) - 1)
fatal("%s: kexname too short \"%s\"", __func__, kexname);
return key_curve_name_to_nid(kexname + sizeof(KEX_ECDH_SHA2_STEM) - 1);
}
const EVP_MD *
kex_ecdh_name_to_evpmd(const char *kexname)
{
int nid = kex_ecdh_name_to_nid(kexname);
if (nid == -1)
fatal("%s: unsupported ECDH curve \"%s\"", __func__, kexname);
return key_ec_nid_to_evpmd(nid);
}
void
kex_ecdh_hash(
const EVP_MD *evp_md,
const EC_GROUP *ec_group,
char *client_version_string,
char *server_version_string,
char *ckexinit, int ckexinitlen,
char *skexinit, int skexinitlen,
u_char *serverhostkeyblob, int sbloblen,
const EC_POINT *client_dh_pub,
const EC_POINT *server_dh_pub,
const BIGNUM *shared_secret,
u_char **hash, u_int *hashlen)
{
Buffer b;
EVP_MD_CTX md;
static u_char digest[EVP_MAX_MD_SIZE];
buffer_init(&b);
buffer_put_cstring(&b, client_version_string);
buffer_put_cstring(&b, server_version_string);
/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
buffer_put_int(&b, ckexinitlen+1);
buffer_put_char(&b, SSH2_MSG_KEXINIT);
buffer_append(&b, ckexinit, ckexinitlen);
buffer_put_int(&b, skexinitlen+1);
buffer_put_char(&b, SSH2_MSG_KEXINIT);
buffer_append(&b, skexinit, skexinitlen);
buffer_put_string(&b, serverhostkeyblob, sbloblen);
buffer_put_ecpoint(&b, ec_group, client_dh_pub);
buffer_put_ecpoint(&b, ec_group, server_dh_pub);
buffer_put_bignum2(&b, shared_secret);
#ifdef DEBUG_KEX
buffer_dump(&b);
#endif
EVP_DigestInit(&md, evp_md);
EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
EVP_DigestFinal(&md, digest, NULL);
buffer_free(&b);
#ifdef DEBUG_KEX
dump_digest("hash", digest, EVP_MD_size(evp_md));
#endif
*hash = digest;
*hashlen = EVP_MD_size(evp_md);
}
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