--- /dev/null
+/*
+ * Copyright (c) 2000 Niels Provos. All rights reserved.
+ * 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: kexgexc.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 "compat.h"
+
+void
+kexgex_client(Kex *kex)
+{
+ BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+ BIGNUM *p = NULL, *g = NULL;
+ Key *server_host_key;
+ u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
+ u_int klen, kout, slen, sbloblen;
+ int min, max, nbits;
+ DH *dh;
+
+ nbits = dh_estimate(kex->we_need * 8);
+
+ if (datafellows & SSH_OLD_DHGEX) {
+ debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD sent");
+
+ /* Old GEX request */
+ packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
+ packet_put_int(nbits);
+ min = DH_GRP_MIN;
+ max = DH_GRP_MAX;
+ } else {
+ debug("SSH2_MSG_KEX_DH_GEX_REQUEST sent");
+
+ /* New GEX request */
+ min = DH_GRP_MIN;
+ max = DH_GRP_MAX;
+ packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
+ packet_put_int(min);
+ packet_put_int(nbits);
+ packet_put_int(max);
+ }
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
+ min, nbits, max);
+#endif
+ packet_send();
+
+ debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
+ packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
+
+ if ((p = BN_new()) == NULL)
+ fatal("BN_new");
+ packet_get_bignum2(p);
+ if ((g = BN_new()) == NULL)
+ fatal("BN_new");
+ packet_get_bignum2(g);
+ packet_check_eom();
+
+ if (BN_num_bits(p) < min || BN_num_bits(p) > max)
+ fatal("DH_GEX group out of range: %d !< %d !< %d",
+ min, BN_num_bits(p), max);
+
+ dh = dh_new_group(g, p);
+ dh_gen_key(dh, kex->we_need * 8);
+
+#ifdef DEBUG_KEXDH
+ DHparams_print_fp(stderr, dh);
+ fprintf(stderr, "pub= ");
+ BN_print_fp(stderr, dh->pub_key);
+ fprintf(stderr, "\n");
+#endif
+
+ debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
+ /* generate and send 'e', client DH public key */
+ packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
+ packet_put_bignum2(dh->pub_key);
+ packet_send();
+
+ debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
+ packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
+
+ /* key, cert */
+ 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");
+
+ /* DH paramter f, server public DH key */
+ if ((dh_server_pub = BN_new()) == NULL)
+ fatal("dh_server_pub == NULL");
+ packet_get_bignum2(dh_server_pub);
+
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "dh_server_pub= ");
+ BN_print_fp(stderr, dh_server_pub);
+ fprintf(stderr, "\n");
+ debug("bits %d", BN_num_bits(dh_server_pub));
+#endif
+
+ /* signed H */
+ signature = packet_get_string(&slen);
+ packet_check_eom();
+
+ if (!dh_pub_is_valid(dh, dh_server_pub))
+ packet_disconnect("bad server public DH value");
+
+ klen = DH_size(dh);
+ kbuf = xmalloc(klen);
+ kout = DH_compute_key(kbuf, dh_server_pub, dh);
+#ifdef DEBUG_KEXDH
+ dump_digest("shared secret", kbuf, kout);
+#endif
+ if ((shared_secret = BN_new()) == NULL)
+ fatal("kexgex_client: BN_new failed");
+ BN_bin2bn(kbuf, kout, shared_secret);
+ memset(kbuf, 0, klen);
+ xfree(kbuf);
+
+ if (datafellows & SSH_OLD_DHGEX)
+ min = max = -1;
+
+ /* calc and verify H */
+ hash = kexgex_hash(
+ 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,
+ min, nbits, max,
+ dh->p, dh->g,
+ dh->pub_key,
+ dh_server_pub,
+ shared_secret
+ );
+ /* have keys, free DH */
+ DH_free(dh);
+ xfree(server_host_key_blob);
+ BN_clear_free(dh_server_pub);
+
+ if (key_verify(server_host_key, signature, slen, hash, 20) != 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 = 20;
+ kex->session_id = xmalloc(kex->session_id_len);
+ memcpy(kex->session_id, hash, kex->session_id_len);
+ }
+ kex_derive_keys(kex, hash, shared_secret);
+ BN_clear_free(shared_secret);
+
+ kex_finish(kex);
+}
andersk / openssh.git / blobdiff