1 files changed, 222 insertions, 0 deletions
diff --git a/kexecdhc.c b/kexecdhc.c
new file mode 100644
index 0000000..ac146a3
--- /dev/null
+++ b/kexecdhc.c
@@ -0,0 +1,222 @@
+/* $OpenBSD: kexecdhc.c,v 1.13 2018/02/07 02:06:51 jsing 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 <openssl/ecdh.h>
+
+#include "sshkey.h"
+#include "cipher.h"
+#include "digest.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "dh.h"
+#include "ssh2.h"
+#include "dispatch.h"
+#include "compat.h"
+#include "ssherr.h"
+#include "sshbuf.h"
+
+static int input_kex_ecdh_reply(int, u_int32_t, struct ssh *);
+
+int
+kexecdh_client(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	EC_KEY *client_key = NULL;
+	const EC_GROUP *group;
+	const EC_POINT *public_key;
+	int r;
+
+	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (EC_KEY_generate_key(client_key) != 1) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	group = EC_KEY_get0_group(client_key);
+	public_key = EC_KEY_get0_public_key(client_key);
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
+	    (r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		goto out;
+	debug("sending SSH2_MSG_KEX_ECDH_INIT");
+
+#ifdef DEBUG_KEXECDH
+	fputs("client private key:\n", stderr);
+	sshkey_dump_ec_key(client_key);
+#endif
+	kex->ec_client_key = client_key;
+	kex->ec_group = group;
+	client_key = NULL;	/* owned by the kex */
+
+	debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
+	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_ecdh_reply);
+	r = 0;
+ out:
+	EC_KEY_free(client_key);
+	return r;
+}
+
+static int
+input_kex_ecdh_reply(int type, u_int32_t seq, struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	const EC_GROUP *group;
+	EC_POINT *server_public = NULL;
+	EC_KEY *client_key;
+	BIGNUM *shared_secret = NULL;
+	struct sshkey *server_host_key = NULL;
+	u_char *server_host_key_blob = NULL, *signature = NULL;
+	u_char *kbuf = NULL;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t slen, sbloblen;
+	size_t klen = 0, hashlen;
+	int r;
+
+	if (kex->verify_host_key == NULL) {
+		r = SSH_ERR_INVALID_ARGUMENT;
+		goto out;
+	}
+	group = kex->ec_group;
+	client_key = kex->ec_client_key;
+
+	/* hostkey */
+	if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
+	    &sbloblen)) != 0 ||
+	    (r = sshkey_from_blob(server_host_key_blob, sbloblen,
+	    &server_host_key)) != 0)
+		goto out;
+	if (server_host_key->type != kex->hostkey_type ||
+	    (kex->hostkey_type == KEY_ECDSA &&
+	    server_host_key->ecdsa_nid != kex->hostkey_nid)) {
+		r = SSH_ERR_KEY_TYPE_MISMATCH;
+		goto out;
+	}
+	if (kex->verify_host_key(server_host_key, ssh) == -1) {
+		r = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	}
+
+	/* Q_S, server public key */
+	/* signed H */
+	if ((server_public = EC_POINT_new(group)) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 ||
+	    (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		goto out;
+
+#ifdef DEBUG_KEXECDH
+	fputs("server public key:\n", stderr);
+	sshkey_dump_ec_point(group, server_public);
+#endif
+	if (sshkey_ec_validate_public(group, server_public) != 0) {
+		sshpkt_disconnect(ssh, "invalid server public key");
+		r = SSH_ERR_MESSAGE_INCOMPLETE;
+		goto out;
+	}
+
+	klen = (EC_GROUP_get_degree(group) + 7) / 8;
+	if ((kbuf = malloc(klen)) == NULL ||
+	    (shared_secret = BN_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (ECDH_compute_key(kbuf, klen, server_public,
+	    client_key, NULL) != (int)klen ||
+	    BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+
+#ifdef DEBUG_KEXECDH
+	dump_digest("shared secret", kbuf, klen);
+#endif
+	/* calc and verify H */
+	hashlen = sizeof(hash);
+	if ((r = kex_ecdh_hash(
+	    kex->hash_alg,
+	    group,
+	    kex->client_version_string,
+	    kex->server_version_string,
+	    sshbuf_ptr(kex->my), sshbuf_len(kex->my),
+	    sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
+	    server_host_key_blob, sbloblen,
+	    EC_KEY_get0_public_key(client_key),
+	    server_public,
+	    shared_secret,
+	    hash, &hashlen)) != 0)
+		goto out;
+
+	if ((r = sshkey_verify(server_host_key, signature, slen, hash,
+	    hashlen, kex->hostkey_alg, ssh->compat)) != 0)
+		goto out;
+
+	/* save session id */
+	if (kex->session_id == NULL) {
+		kex->session_id_len = hashlen;
+		kex->session_id = malloc(kex->session_id_len);
+		if (kex->session_id == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		memcpy(kex->session_id, hash, kex->session_id_len);
+	}
+
+	if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+ out:
+	explicit_bzero(hash, sizeof(hash));
+	EC_KEY_free(kex->ec_client_key);
+	kex->ec_client_key = NULL;
+	EC_POINT_clear_free(server_public);
+	if (kbuf) {
+		explicit_bzero(kbuf, klen);
+		free(kbuf);
+	}
+	BN_clear_free(shared_secret);
+	sshkey_free(server_host_key);
+	free(server_host_key_blob);
+	free(signature);
+	return r;
+}
+#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */
+