| /* $OpenBSD: kexecdhc.c,v 1.8 2015/01/19 19:52:16 markus 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 "includes.h" |
| |
| #if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) |
| |
| #include <sys/types.h> |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <signal.h> |
| |
| #include "xmalloc.h" |
| #include "buffer.h" |
| #include "key.h" |
| #include "cipher.h" |
| #include "kex.h" |
| #include "log.h" |
| #include "packet.h" |
| #include "dh.h" |
| #include "ssh2.h" |
| |
| #include <openssl/ecdh.h> |
| |
| void |
| kexecdh_client(Kex *kex) |
| { |
| EC_KEY *client_key; |
| EC_POINT *server_public; |
| const EC_GROUP *group; |
| BIGNUM *shared_secret; |
| Key *server_host_key; |
| u_char *server_host_key_blob = NULL, *signature = NULL; |
| u_char *kbuf, *hash; |
| u_int klen, slen, sbloblen, hashlen; |
| |
| if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) |
| fatal("%s: EC_KEY_new_by_curve_name failed", __func__); |
| if (EC_KEY_generate_key(client_key) != 1) |
| fatal("%s: EC_KEY_generate_key failed", __func__); |
| group = EC_KEY_get0_group(client_key); |
| |
| packet_start(SSH2_MSG_KEX_ECDH_INIT); |
| packet_put_ecpoint(group, EC_KEY_get0_public_key(client_key)); |
| packet_send(); |
| debug("sending SSH2_MSG_KEX_ECDH_INIT"); |
| |
| #ifdef DEBUG_KEXECDH |
| fputs("client private key:\n", stderr); |
| key_dump_ec_key(client_key); |
| #endif |
| |
| debug("expecting SSH2_MSG_KEX_ECDH_REPLY"); |
| packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY); |
| |
| /* hostkey */ |
| server_host_key_blob = packet_get_string(&sbloblen); |
| server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
| if (server_host_key == NULL) |
| fatal("cannot decode server_host_key_blob"); |
| if (server_host_key->type != kex->hostkey_type) |
| fatal("type mismatch for decoded server_host_key_blob"); |
| if (kex->verify_host_key == NULL) |
| fatal("cannot verify server_host_key"); |
| if (kex->verify_host_key(server_host_key) == -1) |
| fatal("server_host_key verification failed"); |
| |
| /* Q_S, server public key */ |
| if ((server_public = EC_POINT_new(group)) == NULL) |
| fatal("%s: EC_POINT_new failed", __func__); |
| packet_get_ecpoint(group, server_public); |
| |
| if (key_ec_validate_public(group, server_public) != 0) |
| fatal("%s: invalid server public key", __func__); |
| |
| #ifdef DEBUG_KEXECDH |
| fputs("server public key:\n", stderr); |
| key_dump_ec_point(group, server_public); |
| #endif |
| |
| /* signed H */ |
| signature = packet_get_string(&slen); |
| packet_check_eom(); |
| |
| klen = (EC_GROUP_get_degree(group) + 7) / 8; |
| kbuf = xmalloc(klen); |
| if (ECDH_compute_key(kbuf, klen, server_public, |
| client_key, NULL) != (int)klen) |
| fatal("%s: ECDH_compute_key failed", __func__); |
| |
| #ifdef DEBUG_KEXECDH |
| dump_digest("shared secret", kbuf, klen); |
| #endif |
| if ((shared_secret = BN_new()) == NULL) |
| fatal("%s: BN_new failed", __func__); |
| if (BN_bin2bn(kbuf, klen, shared_secret) == NULL) |
| fatal("%s: BN_bin2bn failed", __func__); |
| explicit_bzero(kbuf, klen); |
| free(kbuf); |
| |
| /* calc and verify H */ |
| kex_ecdh_hash( |
| kex->hash_alg, |
| group, |
| kex->client_version_string, |
| kex->server_version_string, |
| buffer_ptr(kex->my), buffer_len(kex->my), |
| buffer_ptr(kex->peer), buffer_len(kex->peer), |
| server_host_key_blob, sbloblen, |
| EC_KEY_get0_public_key(client_key), |
| server_public, |
| shared_secret, |
| &hash, &hashlen |
| ); |
| free(server_host_key_blob); |
| EC_POINT_clear_free(server_public); |
| EC_KEY_free(client_key); |
| |
| if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1) |
| fatal("key_verify failed for server_host_key"); |
| key_free(server_host_key); |
| free(signature); |
| |
| /* save session id */ |
| if (kex->session_id == NULL) { |
| kex->session_id_len = hashlen; |
| kex->session_id = xmalloc(kex->session_id_len); |
| memcpy(kex->session_id, hash, kex->session_id_len); |
| } |
| |
| kex_derive_keys_bn(kex, hash, hashlen, shared_secret); |
| BN_clear_free(shared_secret); |
| kex_finish(kex); |
| } |
| #endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */ |