- 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@

12 files changed, 697 insertions, 583 deletions

diff --git a/ChangeLog b/ChangeLog
index 586c10b5b..2fdcb2782 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -63,6 +63,10 @@
    - markus@cvs.openbsd.org 2003/02/12 21:39:50
      [crc32.c crc32.h]
      replace crc32.c with a BSD licensed version; noted by David Turner
+   - 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@
 
 20030211
  - (djm) Cygwin needs libcrypt too. Patch from vinschen@redhat.com
@@ -1163,4 +1167,4 @@
      save auth method before monitor_reset_key_state(); bugzilla bug #284;
      ok provos@
 
-$Id: ChangeLog,v 1.2611 2003/02/24 01:02:12 djm Exp $
+$Id: ChangeLog,v 1.2612 2003/02/24 01:03:03 djm Exp $
diff --git a/kex.c b/kex.c
index 0a861fb97..2c1cacfec 100644
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.53 2003/02/02 10:56:08 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.54 2003/02/16 17:09:57 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -44,11 +44,6 @@ RCSID("$OpenBSD: kex.c,v 1.53 2003/02/02 10:56:08 markus Exp $");
 
 #define KEX_COOKIE_LEN	16
 
-/* Use privilege separation for sshd */
-int use_privsep;
-struct monitor *pmonitor;
-
-
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
@@ -237,14 +232,10 @@ kex_kexinit_finish(Kex *kex)
 
 	kex_choose_conf(kex);
 
-	switch (kex->kex_type) {
-	case DH_GRP1_SHA1:
-		kexdh(kex);
-		break;
-	case DH_GEX_SHA1:
-		kexgex(kex);
-		break;
-	default:
+	if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
+	    kex->kex[kex->kex_type] != NULL) {
+		(kex->kex[kex->kex_type])(kex);
+	} else {
 		fatal("Unsupported key exchange %d", kex->kex_type);
 	}
 }
@@ -301,9 +292,9 @@ choose_kex(Kex *k, char *client, char *server)
 	if (k->name == NULL)
 		fatal("no kex alg");
 	if (strcmp(k->name, KEX_DH1) == 0) {
-		k->kex_type = DH_GRP1_SHA1;
+		k->kex_type = KEX_DH_GRP1_SHA1;
 	} else if (strcmp(k->name, KEX_DHGEX) == 0) {
-		k->kex_type = DH_GEX_SHA1;
+		k->kex_type = KEX_DH_GEX_SHA1;
 	} else
 		fatal("bad kex alg %s", k->name);
 }
diff --git a/kex.h b/kex.h
index 93a529e12..52d442e9a 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kex.h,v 1.32 2002/09/09 14:54:14 markus Exp $	*/
+/*	$OpenBSD: kex.h,v 1.33 2003/02/16 17:09:57 markus Exp $	*/
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -55,8 +55,9 @@ enum kex_modes {
 };
 
 enum kex_exchange {
-	DH_GRP1_SHA1,
-	DH_GEX_SHA1
+	KEX_DH_GRP1_SHA1,
+	KEX_DH_GEX_SHA1,
+	KEX_MAX
 };
 
 #define KEX_INIT_SENT	0x0001
@@ -112,6 +113,7 @@ struct Kex {
 	int	(*verify_host_key)(Key *);
 	Key	*(*load_host_key)(int);
 	int	(*host_key_index)(Key *);
+	void	(*kex[KEX_MAX])(Kex *);
 };
 
 Kex	*kex_setup(char *[PROPOSAL_MAX]);
@@ -121,11 +123,20 @@ void	 kex_send_kexinit(Kex *);
 void	 kex_input_kexinit(int, u_int32_t, void *);
 void	 kex_derive_keys(Kex *, u_char *, BIGNUM *);
 
-void	 kexdh(Kex *);
-void	 kexgex(Kex *);
-
 Newkeys *kex_get_newkeys(int);
 
+void	 kexdh_client(Kex *);
+void	 kexdh_server(Kex *);
+void	 kexgex_client(Kex *);
+void	 kexgex_server(Kex *);
+
+u_char *
+kex_dh_hash(char *, char *, char *, int, char *, int, u_char *, int,
+    BIGNUM *, BIGNUM *, BIGNUM *);
+u_char *
+kexgex_hash(char *, char *, char *, int, char *, int, u_char *, int,
+    int, int, int, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *);
+
 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
 void	dump_digest(char *, u_char *, int);
 #endif
diff --git a/kexdh.c b/kexdh.c
index 1e91e2550..4bbb7d1db 100644
--- a/kexdh.c
+++ b/kexdh.c
@@ -23,23 +23,16 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexdh.c,v 1.18 2002/03/18 17:50:31 provos Exp $");
+RCSID("$OpenBSD: kexdh.c,v 1.19 2003/02/16 17:09:57 markus Exp $");
 
-#include <openssl/crypto.h>
-#include <openssl/bn.h>
+#include <openssl/evp.h>
 
-#include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
-#include "key.h"
-#include "kex.h"
-#include "log.h"
-#include "packet.h"
-#include "dh.h"
 #include "ssh2.h"
-#include "monitor_wrap.h"
+#include "kex.h"
 
-static u_char *
+u_char *
 kex_dh_hash(
     char *client_version_string,
     char *server_version_string,
@@ -86,222 +79,3 @@ kex_dh_hash(
 #endif
 	return digest;
 }
-
-/* client */
-
-static void
-kexdh_client(Kex *kex)
-{
-	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
-	DH *dh;
-	Key *server_host_key;
-	u_char *server_host_key_blob = NULL, *signature = NULL;
-	u_char *kbuf, *hash;
-	u_int klen, kout, slen, sbloblen;
-
-	/* generate and send 'e', client DH public key */
-	dh = dh_new_group1();
-	dh_gen_key(dh, kex->we_need * 8);
-	packet_start(SSH2_MSG_KEXDH_INIT);
-	packet_put_bignum2(dh->pub_key);
-	packet_send();
-
-	debug("sending SSH2_MSG_KEXDH_INIT");
-#ifdef DEBUG_KEXDH
-	DHparams_print_fp(stderr, dh);
-	fprintf(stderr, "pub= ");
-	BN_print_fp(stderr, dh->pub_key);
-	fprintf(stderr, "\n");
-#endif
-
-	debug("expecting SSH2_MSG_KEXDH_REPLY");
-	packet_read_expect(SSH2_MSG_KEXDH_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("kexdh_client: BN_new failed");
-	BN_bin2bn(kbuf, kout, shared_secret);
-	memset(kbuf, 0, klen);
-	xfree(kbuf);
-
-	/* calc and verify H */
-	hash = kex_dh_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,
-	    dh->pub_key,
-	    dh_server_pub,
-	    shared_secret
-	);
-	xfree(server_host_key_blob);
-	BN_clear_free(dh_server_pub);
-	DH_free(dh);
-
-	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);
-}
-
-/* server */
-
-static 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);
-}
-
-void
-kexdh(Kex *kex)
-{
-	if (kex->server)
-		kexdh_server(kex);
-	else
-		kexdh_client(kex);
-}
diff --git a/kexdhc.c b/kexdhc.c
new file mode 100644
index 000000000..fe6dc53f8
--- /dev/null
+++ b/kexdhc.c
@@ -0,0 +1,137 @@
+/*
+ * 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: kexdhc.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"
+
+void
+kexdh_client(Kex *kex)
+{
+	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+	DH *dh;
+	Key *server_host_key;
+	u_char *server_host_key_blob = NULL, *signature = NULL;
+	u_char *kbuf, *hash;
+	u_int klen, kout, slen, sbloblen;
+
+	/* generate and send 'e', client DH public key */
+	dh = dh_new_group1();
+	dh_gen_key(dh, kex->we_need * 8);
+	packet_start(SSH2_MSG_KEXDH_INIT);
+	packet_put_bignum2(dh->pub_key);
+	packet_send();
+
+	debug("sending SSH2_MSG_KEXDH_INIT");
+#ifdef DEBUG_KEXDH
+	DHparams_print_fp(stderr, dh);
+	fprintf(stderr, "pub= ");
+	BN_print_fp(stderr, dh->pub_key);
+	fprintf(stderr, "\n");
+#endif
+
+	debug("expecting SSH2_MSG_KEXDH_REPLY");
+	packet_read_expect(SSH2_MSG_KEXDH_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("kexdh_client: BN_new failed");
+	BN_bin2bn(kbuf, kout, shared_secret);
+	memset(kbuf, 0, klen);
+	xfree(kbuf);
+
+	/* calc and verify H */
+	hash = kex_dh_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,
+	    dh->pub_key,
+	    dh_server_pub,
+	    shared_secret
+	);
+	xfree(server_host_key_blob);
+	BN_clear_free(dh_server_pub);
+	DH_free(dh);
+
+	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);
+}
diff --git a/kexdhs.c b/kexdhs.c
new file mode 100644
index 000000000..f04bce825
--- /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);
+}
diff --git a/kexgex.c b/kexgex.c
index 2d4a58153..b0c39c8cb 100644
--- a/kexgex.c
+++ b/kexgex.c
@@ -24,23 +24,16 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexgex.c,v 1.22 2002/03/24 17:27:03 stevesk Exp $");
+RCSID("$OpenBSD: kexgex.c,v 1.23 2003/02/16 17:09:57 markus Exp $");
 
-#include <openssl/bn.h>
+#include <openssl/evp.h>
 
-#include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
-#include "key.h"
 #include "kex.h"
-#include "log.h"
-#include "packet.h"
-#include "dh.h"
 #include "ssh2.h"
-#include "compat.h"
-#include "monitor_wrap.h"
 
-static u_char *
+u_char *
 kexgex_hash(
     char *client_version_string,
     char *server_version_string,
@@ -97,318 +90,3 @@ kexgex_hash(
 #endif
 	return digest;
 }
-
-/* client */
-
-static 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);
-}
-
-/* server */
-
-static void
-kexgex_server(Kex *kex)
-{
-	BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
-	Key *server_host_key;
-	DH *dh;
-	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
-	u_int sbloblen, klen, kout, slen;
-	int min = -1, max = -1, nbits = -1, type;
-
-	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);
-
-	type = packet_read();
-	switch (type) {
-	case SSH2_MSG_KEX_DH_GEX_REQUEST:
-		debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
-		min = packet_get_int();
-		nbits = packet_get_int();
-		max = packet_get_int();
-		min = MAX(DH_GRP_MIN, min);
-		max = MIN(DH_GRP_MAX, max);
-		break;
-	case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
-		debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
-		nbits = packet_get_int();
-		min = DH_GRP_MIN;
-		max = DH_GRP_MAX;
-		/* unused for old GEX */
-		break;
-	default:
-		fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
-	}
-	packet_check_eom();
-
-	if (max < min || nbits < min || max < nbits)
-		fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
-		    min, nbits, max);
-
-	/* Contact privileged parent */
-	dh = PRIVSEP(choose_dh(min, nbits, max));
-	if (dh == NULL)
-		packet_disconnect("Protocol error: no matching DH grp found");
-
-	debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
-	packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
-	packet_put_bignum2(dh->p);
-	packet_put_bignum2(dh->g);
-	packet_send();
-
-	/* flush */
-	packet_write_wait();
-
-	/* Compute our exchange value in parallel with the client */
-	dh_gen_key(dh, kex->we_need * 8);
-
-	debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
-	packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
-
-	/* 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("kexgex_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);
-
-	if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
-		min = max = -1;
-
-	/* calc H */			/* XXX depends on 'kex' */
-	hash = kexgex_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,
-	    min, nbits, max,
-	    dh->p, dh->g,
-	    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 */
-	debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
-	packet_start(SSH2_MSG_KEX_DH_GEX_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);
-}
-
-void
-kexgex(Kex *kex)
-{
-	if (kex->server)
-		kexgex_server(kex);
-	else
-		kexgex_client(kex);
-}
diff --git a/kexgexc.c b/kexgexc.c
new file mode 100644
index 000000000..f14ac44ca
--- /dev/null
+++ b/kexgexc.c
@@ -0,0 +1,189 @@
+/*
+ * 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);
+}
diff --git a/kexgexs.c b/kexgexs.c
new file mode 100644
index 000000000..baebfcfb0
--- /dev/null
+++ b/kexgexs.c
@@ -0,0 +1,186 @@
+/*
+ * 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: kexgexs.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"
+#include "monitor_wrap.h"
+
+void
+kexgex_server(Kex *kex)
+{
+	BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
+	Key *server_host_key;
+	DH *dh;
+	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
+	u_int sbloblen, klen, kout, slen;
+	int min = -1, max = -1, nbits = -1, type;
+
+	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);
+
+	type = packet_read();
+	switch (type) {
+	case SSH2_MSG_KEX_DH_GEX_REQUEST:
+		debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
+		min = packet_get_int();
+		nbits = packet_get_int();
+		max = packet_get_int();
+		min = MAX(DH_GRP_MIN, min);
+		max = MIN(DH_GRP_MAX, max);
+		break;
+	case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
+		debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
+		nbits = packet_get_int();
+		min = DH_GRP_MIN;
+		max = DH_GRP_MAX;
+		/* unused for old GEX */
+		break;
+	default:
+		fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
+	}
+	packet_check_eom();
+
+	if (max < min || nbits < min || max < nbits)
+		fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
+		    min, nbits, max);
+
+	/* Contact privileged parent */
+	dh = PRIVSEP(choose_dh(min, nbits, max));
+	if (dh == NULL)
+		packet_disconnect("Protocol error: no matching DH grp found");
+
+	debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
+	packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
+	packet_put_bignum2(dh->p);
+	packet_put_bignum2(dh->g);
+	packet_send();
+
+	/* flush */
+	packet_write_wait();
+
+	/* Compute our exchange value in parallel with the client */
+	dh_gen_key(dh, kex->we_need * 8);
+
+	debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
+	packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
+
+	/* 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("kexgex_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);
+
+	if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
+		min = max = -1;
+
+	/* calc H */			/* XXX depends on 'kex' */
+	hash = kexgex_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,
+	    min, nbits, max,
+	    dh->p, dh->g,
+	    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 */
+	debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
+	packet_start(SSH2_MSG_KEX_DH_GEX_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);
+}
diff --git a/ssh-keyscan.c b/ssh-keyscan.c
index 8c14d6d26..5b4eb82d1 100644
--- a/ssh-keyscan.c
+++ b/ssh-keyscan.c
@@ -7,7 +7,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: ssh-keyscan.c,v 1.40 2002/07/06 17:47:58 stevesk Exp $");
+RCSID("$OpenBSD: ssh-keyscan.c,v 1.41 2003/02/16 17:09:57 markus Exp $");
 
 #include "openbsd-compat/sys-queue.h"
 
@@ -354,6 +354,8 @@ keygrab_ssh2(con *c)
 	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = c->c_keytype == KT_DSA?
 	    "ssh-dss": "ssh-rsa";
 	c->c_kex = kex_setup(myproposal);
+	c->c_kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
+	c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 	c->c_kex->verify_host_key = hostjump;
 
 	if (!(j = setjmp(kexjmp))) {
diff --git a/sshconnect2.c b/sshconnect2.c
index de33e142b..81d1b91c7 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.110 2002/12/19 00:07:02 djm Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.111 2003/02/16 17:09:57 markus Exp $");
 
 #include "ssh.h"
 #include "ssh2.h"
@@ -110,6 +110,8 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
 
 	/* start key exchange */
 	kex = kex_setup(myproposal);
+	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
+	kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 	kex->client_version_string=client_version_string;
 	kex->server_version_string=server_version_string;
 	kex->verify_host_key=&verify_host_key_callback;
diff --git a/sshd.c b/sshd.c
index ca2d4d1bc..86441cff1 100644
--- a/sshd.c
+++ b/sshd.c
@@ -42,7 +42,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.262 2003/01/27 17:06:31 markus Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.263 2003/02/16 17:09:57 markus Exp $");
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
@@ -202,8 +202,8 @@ int *startup_pipes = NULL;
 int startup_pipe;		/* in child */
 
 /* variables used for privilege separation */
-extern struct monitor *pmonitor;
-extern int use_privsep;
+int use_privsep;
+struct monitor *pmonitor;
 
 /* Prototypes for various functions defined later in this file. */
 void destroy_sensitive_data(void);
@@ -1814,6 +1814,8 @@ do_ssh2_kex(void)
 
 	/* start key exchange */
 	kex = kex_setup(myproposal);
+	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+	kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
 	kex->server = 1;
 	kex->client_version_string=client_version_string;
 	kex->server_version_string=server_version_string;