- markus@cvs.openbsd.org 2003/02/16 17:09:57
[kex.c kexdh.c kexgex.c kex.h sshconnect2.c sshd.c ssh-keyscan.c]
split kex into client and server code, no need to link
server code into the client; ok provos@
diff --git a/kexdhs.c b/kexdhs.c
new file mode 100644
index 0000000..f04bce8
--- /dev/null
+++ b/kexdhs.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2001 Markus Friedl. 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"
+RCSID("$OpenBSD: kexdhs.c,v 1.1 2003/02/16 17:09:57 markus Exp $");
+
+#include "xmalloc.h"
+#include "key.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "dh.h"
+#include "ssh2.h"
+#include "monitor_wrap.h"
+
+void
+kexdh_server(Kex *kex)
+{
+ BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
+ DH *dh;
+ Key *server_host_key;
+ u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
+ u_int sbloblen, klen, kout;
+ u_int slen;
+
+ /* generate server DH public key */
+ dh = dh_new_group1();
+ dh_gen_key(dh, kex->we_need * 8);
+
+ debug("expecting SSH2_MSG_KEXDH_INIT");
+ packet_read_expect(SSH2_MSG_KEXDH_INIT);
+
+ if (kex->load_host_key == NULL)
+ fatal("Cannot load hostkey");
+ server_host_key = kex->load_host_key(kex->hostkey_type);
+ if (server_host_key == NULL)
+ fatal("Unsupported hostkey type %d", kex->hostkey_type);
+
+ /* key, cert */
+ if ((dh_client_pub = BN_new()) == NULL)
+ fatal("dh_client_pub == NULL");
+ packet_get_bignum2(dh_client_pub);
+ packet_check_eom();
+
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "dh_client_pub= ");
+ BN_print_fp(stderr, dh_client_pub);
+ fprintf(stderr, "\n");
+ debug("bits %d", BN_num_bits(dh_client_pub));
+#endif
+
+#ifdef DEBUG_KEXDH
+ DHparams_print_fp(stderr, dh);
+ fprintf(stderr, "pub= ");
+ BN_print_fp(stderr, dh->pub_key);
+ fprintf(stderr, "\n");
+#endif
+ if (!dh_pub_is_valid(dh, dh_client_pub))
+ packet_disconnect("bad client public DH value");
+
+ klen = DH_size(dh);
+ kbuf = xmalloc(klen);
+ kout = DH_compute_key(kbuf, dh_client_pub, dh);
+#ifdef DEBUG_KEXDH
+ dump_digest("shared secret", kbuf, kout);
+#endif
+ if ((shared_secret = BN_new()) == NULL)
+ fatal("kexdh_server: BN_new failed");
+ BN_bin2bn(kbuf, kout, shared_secret);
+ memset(kbuf, 0, klen);
+ xfree(kbuf);
+
+ key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
+
+ /* calc H */
+ hash = kex_dh_hash(
+ 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,
+ dh_client_pub,
+ dh->pub_key,
+ shared_secret
+ );
+ BN_clear_free(dh_client_pub);
+
+ /* save session id := H */
+ /* XXX hashlen depends on KEX */
+ if (kex->session_id == NULL) {
+ kex->session_id_len = 20;
+ kex->session_id = xmalloc(kex->session_id_len);
+ memcpy(kex->session_id, hash, kex->session_id_len);
+ }
+
+ /* sign H */
+ /* XXX hashlen depends on KEX */
+ PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, 20));
+
+ /* destroy_sensitive_data(); */
+
+ /* send server hostkey, DH pubkey 'f' and singed H */
+ packet_start(SSH2_MSG_KEXDH_REPLY);
+ packet_put_string(server_host_key_blob, sbloblen);
+ packet_put_bignum2(dh->pub_key); /* f */
+ packet_put_string(signature, slen);
+ packet_send();
+
+ xfree(signature);
+ xfree(server_host_key_blob);
+ /* have keys, free DH */
+ DH_free(dh);
+
+ kex_derive_keys(kex, hash, shared_secret);
+ BN_clear_free(shared_secret);
+ kex_finish(kex);
+}