2015-01-26 06:10:03 +00:00
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/* $OpenBSD: kexc25519c.c,v 1.7 2015/01/26 06:10:03 djm Exp $ */
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2013-11-04 11:59:27 +00:00
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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* Copyright (c) 2010 Damien Miller. All rights reserved.
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* Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <stdio.h>
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#include <string.h>
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#include <signal.h>
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2015-01-19 20:16:15 +00:00
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#include "sshkey.h"
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2013-11-04 11:59:27 +00:00
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#include "cipher.h"
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#include "kex.h"
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#include "log.h"
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#include "packet.h"
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#include "ssh2.h"
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2015-01-19 20:16:15 +00:00
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#include "sshbuf.h"
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#include "digest.h"
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#include "ssherr.h"
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2013-11-04 11:59:27 +00:00
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2015-01-19 20:16:15 +00:00
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static int
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input_kex_c25519_reply(int type, u_int32_t seq, void *ctxt);
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2013-11-04 11:59:27 +00:00
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2015-01-19 20:16:15 +00:00
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int
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kexc25519_client(struct ssh *ssh)
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{
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struct kex *kex = ssh->kex;
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int r;
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2013-11-04 11:59:27 +00:00
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2015-01-19 20:16:15 +00:00
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kexc25519_keygen(kex->c25519_client_key, kex->c25519_client_pubkey);
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2013-11-04 11:59:27 +00:00
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#ifdef DEBUG_KEXECDH
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2015-01-19 20:16:15 +00:00
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dump_digest("client private key:", kex->c25519_client_key,
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sizeof(kex->c25519_client_key));
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2013-11-04 11:59:27 +00:00
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#endif
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2015-01-19 20:16:15 +00:00
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if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
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(r = sshpkt_put_string(ssh, kex->c25519_client_pubkey,
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sizeof(kex->c25519_client_pubkey))) != 0 ||
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(r = sshpkt_send(ssh)) != 0)
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return r;
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2013-11-04 11:59:27 +00:00
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debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
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2015-01-19 20:16:15 +00:00
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ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_c25519_reply);
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return 0;
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}
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static int
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input_kex_c25519_reply(int type, u_int32_t seq, void *ctxt)
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{
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struct ssh *ssh = ctxt;
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struct kex *kex = ssh->kex;
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struct sshkey *server_host_key = NULL;
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struct sshbuf *shared_secret = NULL;
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u_char *server_pubkey = NULL;
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u_char *server_host_key_blob = NULL, *signature = NULL;
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u_char hash[SSH_DIGEST_MAX_LENGTH];
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size_t slen, pklen, sbloblen, hashlen;
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int r;
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if (kex->verify_host_key == NULL) {
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r = SSH_ERR_INVALID_ARGUMENT;
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goto out;
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}
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2013-11-04 11:59:27 +00:00
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/* hostkey */
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2015-01-19 20:16:15 +00:00
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if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
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&sbloblen)) != 0 ||
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(r = sshkey_from_blob(server_host_key_blob, sbloblen,
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&server_host_key)) != 0)
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goto out;
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2015-01-26 06:10:03 +00:00
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if (server_host_key->type != kex->hostkey_type ||
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(kex->hostkey_type == KEY_ECDSA &&
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server_host_key->ecdsa_nid != kex->hostkey_nid)) {
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2015-01-19 20:16:15 +00:00
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r = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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}
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if (kex->verify_host_key(server_host_key, ssh) == -1) {
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r = SSH_ERR_SIGNATURE_INVALID;
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goto out;
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}
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2013-11-04 11:59:27 +00:00
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/* Q_S, server public key */
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2015-01-19 20:16:15 +00:00
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/* signed H */
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if ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 ||
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(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
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(r = sshpkt_get_end(ssh)) != 0)
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goto out;
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if (pklen != CURVE25519_SIZE) {
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r = SSH_ERR_SIGNATURE_INVALID;
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goto out;
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}
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2013-11-04 11:59:27 +00:00
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#ifdef DEBUG_KEXECDH
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dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
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#endif
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2015-01-19 20:16:15 +00:00
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if ((shared_secret = sshbuf_new()) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey,
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shared_secret)) < 0)
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goto out;
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2013-11-04 11:59:27 +00:00
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/* calc and verify H */
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2015-01-19 20:16:15 +00:00
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hashlen = sizeof(hash);
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if ((r = kex_c25519_hash(
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2014-01-09 23:58:53 +00:00
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kex->hash_alg,
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2013-11-04 11:59:27 +00:00
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kex->client_version_string,
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kex->server_version_string,
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2015-01-19 20:16:15 +00:00
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sshbuf_ptr(kex->my), sshbuf_len(kex->my),
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sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
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2013-11-04 11:59:27 +00:00
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server_host_key_blob, sbloblen,
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2015-01-19 20:16:15 +00:00
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kex->c25519_client_pubkey,
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2013-11-04 11:59:27 +00:00
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server_pubkey,
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2015-01-19 20:16:15 +00:00
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sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
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hash, &hashlen)) < 0)
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goto out;
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if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
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ssh->compat)) != 0)
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goto out;
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2013-11-04 11:59:27 +00:00
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/* save session id */
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if (kex->session_id == NULL) {
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kex->session_id_len = hashlen;
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2015-01-19 20:16:15 +00:00
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kex->session_id = malloc(kex->session_id_len);
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if (kex->session_id == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2013-11-04 11:59:27 +00:00
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memcpy(kex->session_id, hash, kex->session_id_len);
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}
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2015-01-19 20:16:15 +00:00
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if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
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r = kex_send_newkeys(ssh);
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out:
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explicit_bzero(hash, sizeof(hash));
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explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
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free(server_host_key_blob);
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free(server_pubkey);
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free(signature);
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sshkey_free(server_host_key);
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sshbuf_free(shared_secret);
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return r;
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2013-11-04 11:59:27 +00:00
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}
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