1 files changed, 126 insertions, 0 deletions

diff --git a/kexc25519s.c b/kexc25519s.c
new file mode 100644
index 000000000..2b8e8efa1
--- /dev/null
+++ b/kexc25519s.c
@@ -0,0 +1,126 @@
+/* $OpenBSD: kexc25519s.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */
+/*
+ * Copyright (c) 2001 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2010 Damien Miller.  All rights reserved.
+ * Copyright (c) 2013 Aris Adamantiadis.  All rights reserved.
+ *
+ * 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 "ssh2.h"
+
+void
+kexc25519_server(Kex *kex)
+{
+        Key *server_host_private, *server_host_public;
+        u_char *server_host_key_blob = NULL, *signature = NULL;
+        u_char server_key[CURVE25519_SIZE];
+        u_char *client_pubkey = NULL;
+        u_char server_pubkey[CURVE25519_SIZE];
+        u_char *hash;
+        u_int slen, sbloblen, hashlen;
+        Buffer shared_secret;
+
+        /* generate private key */
+        kexc25519_keygen(server_key, server_pubkey);
+#ifdef DEBUG_KEXECDH
+        dump_digest("server private key:", server_key, sizeof(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);
+
+        debug("expecting SSH2_MSG_KEX_ECDH_INIT");
+        packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
+        client_pubkey = packet_get_string(&slen);
+        if (slen != CURVE25519_SIZE)
+                fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
+        packet_check_eom();
+
+#ifdef DEBUG_KEXECDH
+        dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
+#endif
+
+        buffer_init(&shared_secret);
+        kexc25519_shared_key(server_key, client_pubkey, &shared_secret);
+
+        /* calc H */
+        key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
+        kex_c25519_hash(
+            kex->hash_alg,
+            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_pubkey,
+            server_pubkey,
+            buffer_ptr(&shared_secret), buffer_len(&shared_secret),
+            &hash, &hashlen
+        );
+
+        /* 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 */
+        kex->sign(server_host_private, server_host_public, &signature, &slen,
+            hash, hashlen);
+
+        /* 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_string(server_pubkey, sizeof(server_pubkey));
+        packet_put_string(signature, slen);
+        packet_send();
+
+        free(signature);
+        free(server_host_key_blob);
+        /* have keys, free server key */
+        free(client_pubkey);
+
+        kex_derive_keys(kex, hash, hashlen,
+            buffer_ptr(&shared_secret), buffer_len(&shared_secret));
+        buffer_free(&shared_secret);
+        kex_finish(kex);
+}