- (djm) Big OpenBSD sync:
   - markus@cvs.openbsd.org  2000/09/30 10:27:44
     [log.c]
     allow loglevel debug
   - markus@cvs.openbsd.org  2000/10/03 11:59:57
     [packet.c]
     hmac->mac
   - markus@cvs.openbsd.org  2000/10/03 12:03:03
     [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c]
     move fake-auth from auth1.c to individual auth methods, disables s/key in
     debug-msg
   - markus@cvs.openbsd.org  2000/10/03 12:16:48
     ssh.c
     do not resolve canonname, i have no idea why this was added oin ossh
   - markus@cvs.openbsd.org  2000/10/09 15:30:44
     ssh-keygen.1 ssh-keygen.c
     -X now reads private ssh.com DSA keys, too.
   - markus@cvs.openbsd.org  2000/10/09 15:32:34
     auth-options.c
     clear options on every call.
   - markus@cvs.openbsd.org  2000/10/09 15:51:00
     authfd.c authfd.h
     interop with ssh-agent2, from <res@shore.net>
   - markus@cvs.openbsd.org  2000/10/10 14:20:45
     compat.c
     use rexexp for version string matching
   - provos@cvs.openbsd.org  2000/10/10 22:02:18
     [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h]
     First rough implementation of the diffie-hellman group exchange.  The
     client can ask the server for bigger groups to perform the diffie-hellman
     in, thus increasing the attack complexity when using ciphers with longer
     keys.  University of Windsor provided network, T the company.
   - markus@cvs.openbsd.org  2000/10/11 13:59:52
     [auth-rsa.c auth2.c]
     clear auth options unless auth sucessfull
   - markus@cvs.openbsd.org  2000/10/11 14:00:27
     [auth-options.h]
     clear auth options unless auth sucessfull
   - markus@cvs.openbsd.org  2000/10/11 14:03:27
     [scp.1 scp.c]
     support 'scp -o' with help from mouring@pconline.com
   - markus@cvs.openbsd.org  2000/10/11 14:11:35
     [dh.c]
     Wall
   - markus@cvs.openbsd.org  2000/10/11 14:14:40
     [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h]
     [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h]
     add support for s/key (kbd-interactive) to ssh2, based on work by
     mkiernan@avantgo.com and me
   - markus@cvs.openbsd.org  2000/10/11 14:27:24
     [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h]
     [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c]
     [sshconnect2.c sshd.c]
     new cipher framework
   - markus@cvs.openbsd.org  2000/10/11 14:45:21
     [cipher.c]
     remove DES
   - markus@cvs.openbsd.org  2000/10/12 03:59:20
     [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c]
     enable DES in SSH-1 clients only
   - markus@cvs.openbsd.org  2000/10/12 08:21:13
     [kex.h packet.c]
     remove unused
   - markus@cvs.openbsd.org  2000/10/13 12:34:46
     [sshd.c]
     Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se
   - markus@cvs.openbsd.org  2000/10/13 12:59:15
     [cipher.c cipher.h myproposal.h  rijndael.c rijndael.h]
     rijndael/aes support
   - markus@cvs.openbsd.org  2000/10/13 13:10:54
     [sshd.8]
     more info about -V
   - markus@cvs.openbsd.org  2000/10/13 13:12:02
     [myproposal.h]
     prefer no compression
diff --git a/dh.c b/dh.c
new file mode 100644
index 0000000..ff84619
--- /dev/null
+++ b/dh.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2000 Niels Provos.  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: dh.c,v 1.2 2000/10/11 20:11:35 markus Exp $");
+
+#include "xmalloc.h"
+
+#include <openssl/bn.h>
+#include <openssl/dh.h>
+#include <openssl/evp.h>
+
+#include "ssh.h"
+#include "buffer.h"
+#include "kex.h"
+#include "dh.h"
+
+int
+parse_prime(int linenum, char *line, struct dhgroup *dhg)
+{
+	char *cp, *arg;
+	char *strsize, *gen, *prime;
+
+	cp = line;
+	arg = strdelim(&cp);
+	/* Ignore leading whitespace */
+	if (*arg == '\0')
+		arg = strdelim(&cp);
+	if (!*arg || *arg == '#')
+		return 0;
+
+	/* time */
+	if (cp == NULL || *arg == '\0')
+		goto fail;
+	arg = strsep(&cp, " "); /* type */
+	if (cp == NULL || *arg == '\0')
+		goto fail;
+	arg = strsep(&cp, " "); /* tests */
+	if (cp == NULL || *arg == '\0')
+		goto fail;
+	arg = strsep(&cp, " "); /* tries */
+	if (cp == NULL || *arg == '\0')
+		goto fail;
+	strsize = strsep(&cp, " "); /* size */
+	if (cp == NULL || *strsize == '\0' ||
+	    (dhg->size = atoi(strsize)) == 0)
+		goto fail;
+	gen = strsep(&cp, " "); /* gen */
+	if (cp == NULL || *gen == '\0')
+		goto fail;
+	prime = strsep(&cp, " "); /* prime */
+	if (cp != NULL || *prime == '\0')
+		goto fail;
+
+	dhg->g = BN_new();
+	if (BN_hex2bn(&dhg->g, gen) < 0) {
+		BN_free(dhg->g);
+		goto fail;
+	}
+	dhg->p = BN_new();
+	if (BN_hex2bn(&dhg->p, prime) < 0) {
+		BN_free(dhg->g);
+		BN_free(dhg->p);
+		goto fail;
+	}
+
+	return (1);
+ fail:
+	fprintf(stderr, "Bad prime description in line %d\n", linenum);
+	return (0);
+}
+
+DH *
+choose_dh(int minbits)
+{
+	FILE *f;
+	char line[1024];
+	int best, bestcount, which;
+	int linenum;
+	struct dhgroup dhg;
+
+	f = fopen(DH_PRIMES, "r");
+	if (!f) {
+		perror(DH_PRIMES);
+		log("WARNING: %s does not exist, using old prime", DH_PRIMES);
+		return (dh_new_group1());
+	}
+
+	linenum = 0;
+	best = bestcount = 0;
+	while (fgets(line, sizeof(line), f)) {
+		linenum++;
+		if (!parse_prime(linenum, line, &dhg))
+			continue;
+		BN_free(dhg.g);
+		BN_free(dhg.p);
+
+		if ((dhg.size > minbits && dhg.size < best) ||
+		    (dhg.size > best && best < minbits)) {
+			best = dhg.size;
+			bestcount = 0;
+		}
+		if (dhg.size == best)
+			bestcount++;
+	}
+	fclose (f);
+
+	if (bestcount == 0) {
+		log("WARNING: no primes in %s, using old prime", DH_PRIMES);
+		return (dh_new_group1());
+	}
+
+	f = fopen(DH_PRIMES, "r");
+	if (!f) {
+		perror(DH_PRIMES);
+		exit(1);
+	}
+
+	linenum = 0;
+	which = arc4random() % bestcount;
+	while (fgets(line, sizeof(line), f)) {
+		if (!parse_prime(linenum, line, &dhg))
+			continue;
+		if (dhg.size != best)
+			continue;
+		if (linenum++ != which) {
+			BN_free(dhg.g);
+			BN_free(dhg.p);
+			continue;
+		}
+		break;
+	}
+	fclose(f);
+
+	return (dh_new_group(dhg.g, dhg.p));
+}