diff options
Diffstat (limited to 'crypto/openssh/kexecdhc.c')
| -rw-r--r-- | crypto/openssh/kexecdhc.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/crypto/openssh/kexecdhc.c b/crypto/openssh/kexecdhc.c new file mode 100644 index 0000000..115d4bf --- /dev/null +++ b/crypto/openssh/kexecdhc.c @@ -0,0 +1,168 @@ +/* $OpenBSD: kexecdhc.c,v 1.2 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 "includes.h" + +#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" + +#ifdef OPENSSL_HAS_ECC + +#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; + int curve_nid; + + if ((curve_nid = kex_ecdh_name_to_nid(kex->name)) == -1) + fatal("%s: unsupported ECDH curve \"%s\"", __func__, kex->name); + if ((client_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(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__); + memset(kbuf, 0, klen); + xfree(kbuf); + + /* calc and verify H */ + kex_ecdh_hash( + kex->evp_md, + 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 + ); + xfree(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); + xfree(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(kex, hash, hashlen, shared_secret); + BN_clear_free(shared_secret); + kex_finish(kex); +} +#else /* OPENSSL_HAS_ECC */ +void +kexecdh_client(Kex *kex) +{ + fatal("ECC support is not enabled"); +} +#endif /* OPENSSL_HAS_ECC */ |
