| /* $OpenBSD: kexecdhs.c,v 1.1 2010/08/31 11:54:45 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 "includes.h" |
| |
| #include <sys/types.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" |
| #ifdef GSSAPI |
| #include "ssh-gss.h" |
| #endif |
| #include "monitor_wrap.h" |
| |
| #ifdef OPENSSL_HAS_ECC |
| |
| #include <openssl/ecdh.h> |
| |
| void |
| kexecdh_server(Kex *kex) |
| { |
| EC_POINT *client_public; |
| EC_KEY *server_key; |
| const EC_GROUP *group; |
| BIGNUM *shared_secret; |
| Key *server_host_private, *server_host_public; |
| u_char *server_host_key_blob = NULL, *signature = NULL; |
| u_char *kbuf, *hash; |
| u_int klen, slen, sbloblen, hashlen; |
| int curve_nid; |
| |
| curve_nid = kex_ecdh_name_to_nid(kex->name); |
| if ((server_key = EC_KEY_new_by_curve_name(curve_nid)) == NULL) |
| fatal("%s: EC_KEY_new_by_curve_name failed", __func__); |
| if (EC_KEY_generate_key(server_key) != 1) |
| fatal("%s: EC_KEY_generate_key failed", __func__); |
| group = EC_KEY_get0_group(server_key); |
| |
| #ifdef DEBUG_KEXECDH |
| fputs("server private key:\n", stderr); |
| key_dump_ec_key(server_key); |
| #endif |
| |
| if (kex->load_host_public_key == NULL || |
| kex->load_host_private_key == NULL) |
| fatal("Cannot load hostkey"); |
| server_host_public = kex->load_host_public_key(kex->hostkey_type); |
| if (server_host_public == NULL) |
| fatal("Unsupported hostkey type %d", kex->hostkey_type); |
| server_host_private = kex->load_host_private_key(kex->hostkey_type); |
| if (server_host_private == NULL) |
| fatal("Missing private key for hostkey type %d", |
| kex->hostkey_type); |
| |
| debug("expecting SSH2_MSG_KEX_ECDH_INIT"); |
| packet_read_expect(SSH2_MSG_KEX_ECDH_INIT); |
| if ((client_public = EC_POINT_new(group)) == NULL) |
| fatal("%s: EC_POINT_new failed", __func__); |
| packet_get_ecpoint(group, client_public); |
| packet_check_eom(); |
| |
| if (key_ec_validate_public(group, client_public) != 0) |
| fatal("%s: invalid client public key", __func__); |
| |
| #ifdef DEBUG_KEXECDH |
| fputs("client public key:\n", stderr); |
| key_dump_ec_point(group, client_public); |
| #endif |
| |
| /* Calculate shared_secret */ |
| klen = (EC_GROUP_get_degree(group) + 7) / 8; |
| kbuf = xmalloc(klen); |
| if (ECDH_compute_key(kbuf, klen, client_public, |
| server_key, NULL) != (int)klen) |
| fatal("%s: ECDH_compute_key failed", __func__); |
| |
| #ifdef DEBUG_KEXDH |
| 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__); |
| memset(kbuf, 0, klen); |
| xfree(kbuf); |
| |
| /* calc H */ |
| key_to_blob(server_host_public, &server_host_key_blob, &sbloblen); |
| kex_ecdh_hash( |
| kex->evp_md, |
| group, |
| kex->client_version_string, |
| kex->server_version_string, |
| buffer_ptr(&kex->peer), buffer_len(&kex->peer), |
| buffer_ptr(&kex->my), buffer_len(&kex->my), |
| server_host_key_blob, sbloblen, |
| client_public, |
| EC_KEY_get0_public_key(server_key), |
| shared_secret, |
| &hash, &hashlen |
| ); |
| EC_POINT_clear_free(client_public); |
| |
| /* save session id := H */ |
| 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); |
| } |
| |
| /* sign H */ |
| if (PRIVSEP(key_sign(server_host_private, &signature, &slen, |
| hash, hashlen)) < 0) |
| fatal("kexdh_server: key_sign failed"); |
| |
| /* destroy_sensitive_data(); */ |
| |
| /* send server hostkey, ECDH pubkey 'Q_S' and signed H */ |
| packet_start(SSH2_MSG_KEX_ECDH_REPLY); |
| packet_put_string(server_host_key_blob, sbloblen); |
| packet_put_ecpoint(group, EC_KEY_get0_public_key(server_key)); |
| packet_put_string(signature, slen); |
| packet_send(); |
| |
| xfree(signature); |
| xfree(server_host_key_blob); |
| /* have keys, free server key */ |
| EC_KEY_free(server_key); |
| |
| kex_derive_keys(kex, hash, hashlen, shared_secret); |
| BN_clear_free(shared_secret); |
| kex_finish(kex); |
| } |
| #else /* OPENSSL_HAS_ECC */ |
| void |
| kexecdh_server(Kex *kex) |
| { |
| fatal("ECC support is not enabled"); |
| } |
| #endif /* OPENSSL_HAS_ECC */ |