DSA, keyexchange, algorithm agreement for ssh2

7 files changed, 892 insertions, 1 deletions

diff --git a/usr.bin/ssh/dsa.c b/usr.bin/ssh/dsa.c
new file mode 100644
index 00000000000..86c66cbb484
--- /dev/null
+++ b/usr.bin/ssh/dsa.c
@@ -0,0 +1,298 @@
+/*
+ * Copyright (c) 2000 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Markus Friedl.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * 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("$Id: dsa.c,v 1.1 2000/04/03 20:06:14 markus Exp $");
+
+#include "ssh.h"
+#include "xmalloc.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "compat.h"
+
+#include <ssl/bn.h>
+#include <ssl/dh.h>
+#include <ssl/rsa.h>
+#include <ssl/dsa.h>
+#include <ssl/evp.h>
+#include <ssl/bio.h>
+#include <ssl/pem.h>
+
+#include <ssl/hmac.h>
+#include "kex.h"
+#include "key.h"
+
+#define INTBLOB_LEN	20
+#define SIGBLOB_LEN	(2*INTBLOB_LEN)
+
+Key *
+dsa_serverkey_from_blob(
+    char *serverhostkey, int serverhostkeylen)
+{
+	Buffer b;
+	char *ktype;
+	int rlen;
+	DSA *dsa;
+	Key *key;
+
+	/* fetch & parse DSA/DSS pubkey */
+	key = key_new(KEY_DSA);
+	dsa = key->dsa;
+	buffer_init(&b);
+	buffer_append(&b, serverhostkey, serverhostkeylen);
+	ktype = buffer_get_string(&b, NULL);
+	if (strcmp(KEX_DSS, ktype) != 0) {
+		log("dsa_serverkey_from_blob: cannot handle type  %s", ktype);
+		key_free(key);
+		return NULL;
+	}
+	buffer_get_bignum2(&b, dsa->p);
+	buffer_get_bignum2(&b, dsa->q);
+	buffer_get_bignum2(&b, dsa->g);
+	buffer_get_bignum2(&b, dsa->pub_key);
+	rlen = buffer_len(&b);
+	if(rlen != 0)
+		log("dsa_serverkey_from_blob: remaining bytes in serverhostkey %d", rlen);
+	buffer_free(&b);
+
+	log("keytype %s", ktype);
+#ifdef DEBUG_DSS
+	DSA_print_fp(stderr, dsa, 8);
+#endif
+	return key;
+}
+DSA *
+dsa_load_private(char *filename)
+{
+	DSA *dsa;
+	BIO *in;
+
+	in = BIO_new(BIO_s_file());
+	if (in == NULL)
+		fatal("BIO_new failed");
+	if (BIO_read_filename(in, filename) <= 0) 
+		fatal("BIO_read failed %s: %s", filename, strerror(errno));
+	fprintf(stderr, "read DSA private key\n");
+	dsa = PEM_read_bio_DSAPrivateKey(in,NULL,NULL,NULL);
+	if (dsa == NULL)
+		fatal("PEM_read_bio_DSAPrivateKey failed %s", filename);
+	BIO_free(in);
+	return dsa;
+}
+Key *
+dsa_get_serverkey(char *filename)
+{
+	Key *k = key_new(KEY_EMPTY);
+	k->type = KEY_DSA;
+	k->dsa = dsa_load_private(filename);
+#ifdef DEBUG_DSS
+	DSA_print_fp(stderr, dsa, 8);
+#endif
+	return k;
+}
+int
+dsa_make_serverkey_blob(Key *key, unsigned char **blobp, unsigned int *lenp)
+{
+	Buffer b;
+	int len;
+	unsigned char *buf;
+
+	if (key == NULL || key->type != KEY_DSA)
+		return 0;
+	buffer_init(&b);
+	buffer_put_cstring(&b, KEX_DSS);
+	buffer_put_bignum2(&b, key->dsa->p);
+	buffer_put_bignum2(&b, key->dsa->q);
+	buffer_put_bignum2(&b, key->dsa->g);
+	buffer_put_bignum2(&b, key->dsa->pub_key);
+	len = buffer_len(&b);
+	buf = xmalloc(len);
+	memcpy(buf, buffer_ptr(&b), len);
+	memset(buffer_ptr(&b), 0, len);
+	buffer_free(&b);
+	if (lenp != NULL)
+		*lenp = len;
+	if (blobp != NULL)
+		*blobp = buf;
+	return len;
+}
+int
+dsa_sign(
+    Key *key,
+    unsigned char **sigp, int *lenp,
+    unsigned char *hash, int hlen)
+{
+	unsigned char *digest;
+	unsigned char *ret;
+	DSA_SIG *sig;
+	EVP_MD *evp_md = EVP_sha1();
+	EVP_MD_CTX md;
+	unsigned int rlen;
+	unsigned int slen;
+	unsigned int len;
+	unsigned char sigblob[SIGBLOB_LEN];
+	Buffer b;
+
+	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
+		log("dsa_sign: no DSA key");
+		return -1;
+	}
+	digest = xmalloc(evp_md->md_size);
+	EVP_DigestInit(&md, evp_md);
+	EVP_DigestUpdate(&md, hash, hlen);
+	EVP_DigestFinal(&md, digest, NULL);
+
+	sig = DSA_do_sign(digest, evp_md->md_size, key->dsa);
+
+        rlen = BN_num_bytes(sig->r);
+        slen = BN_num_bytes(sig->s);
+        if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
+		log("bad sig size %d %d", rlen, slen);
+		DSA_SIG_free(sig);
+		return -1;
+	}
+	log("sig size %d %d", rlen, slen);
+
+	memset(sigblob, 0, SIGBLOB_LEN);
+	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
+	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
+	DSA_SIG_free(sig);
+
+	if (datafellows) {
+		log("datafellows");
+		ret = xmalloc(SIGBLOB_LEN);
+		memcpy(ret, sigblob, SIGBLOB_LEN);
+		if (lenp != NULL)
+			*lenp = SIGBLOB_LEN;
+		if (sigp != NULL)
+			*sigp = ret;
+	} else {
+		/* ietf-drafts */
+		buffer_init(&b);
+		buffer_put_cstring(&b, KEX_DSS);
+		buffer_put_string(&b, sigblob, SIGBLOB_LEN);
+		len = buffer_len(&b);
+		ret = xmalloc(len);
+		memcpy(ret, buffer_ptr(&b), len);
+		buffer_free(&b);
+		if (lenp != NULL)
+			*lenp = len;
+		if (sigp != NULL)
+			*sigp = ret;
+	}
+	return 0;
+}
+int
+dsa_verify(
+    Key *key,
+    unsigned char *signature, int signaturelen,
+    unsigned char *hash, int hlen)
+{
+	Buffer b;
+	unsigned char *digest;
+	DSA_SIG *sig;
+	EVP_MD *evp_md = EVP_sha1();
+	EVP_MD_CTX md;
+	char *ktype;
+	unsigned char *sigblob;
+	char *txt;
+	unsigned int len;
+	int rlen;
+	int ret;
+
+	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
+		log("dsa_verify: no DSA key");
+		return -1;
+	}
+
+	if (datafellows && signaturelen != SIGBLOB_LEN) {
+		log("heh? datafellows ssh2 complies with ietf-drafts????");
+		datafellows = 0;
+	}
+
+	log("len %d datafellows %d", signaturelen, datafellows);
+
+	/* fetch signature */
+	if (datafellows) {
+		sigblob = signature;
+		len = signaturelen;
+	} else {
+		/* ietf-drafts */
+		buffer_init(&b);
+		buffer_append(&b, (char *) signature, signaturelen);
+		ktype = buffer_get_string(&b, NULL);
+		sigblob = (unsigned char *)buffer_get_string(&b, &len);
+		rlen = buffer_len(&b);
+		if(rlen != 0)
+			log("remaining bytes in signature %d", rlen);
+		buffer_free(&b);
+	}
+
+	if (len != SIGBLOB_LEN) {
+		fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
+	}
+
+	/* parse signature */
+	sig = DSA_SIG_new();
+	sig->r = BN_new();
+	sig->s = BN_new();
+	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
+	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
+	if (!datafellows) {
+		memset(sigblob, 0, len);
+		xfree(sigblob);
+	}
+	
+	/* sha1 the signed data (== session_id == hash) */
+	digest = xmalloc(evp_md->md_size);
+	EVP_DigestInit(&md, evp_md);
+	EVP_DigestUpdate(&md, hash, hlen);
+	EVP_DigestFinal(&md, digest, NULL);
+
+	ret = DSA_do_verify(digest, evp_md->md_size, sig, key->dsa);
+
+	memset(digest, 0, evp_md->md_size);
+	xfree(digest);
+	DSA_SIG_free(sig);
+
+	switch (ret) {
+	case 1:
+		txt = "correct";
+		break;
+	case 0:
+		txt = "incorrect";
+		break;
+	case -1:
+	default:
+		txt = "error";
+		break;
+	}
+	log("dsa_verify: signature %s", txt);
+	return ret;
+}
diff --git a/usr.bin/ssh/dsa.h b/usr.bin/ssh/dsa.h
new file mode 100644
index 00000000000..65e651d9b91
--- /dev/null
+++ b/usr.bin/ssh/dsa.h
@@ -0,0 +1,20 @@
+#ifndef DSA_H
+#define DSA_H
+
+Key	*dsa_serverkey_from_blob(char *serverhostkey, int serverhostkeylen);
+Key	*dsa_get_serverkey(char *filename);
+int	dsa_make_serverkey_blob(Key *key, unsigned char **blobp, unsigned int *lenp);
+
+int
+dsa_sign(
+    Key *key,
+    unsigned char **sigp, int *lenp,
+    unsigned char *hash, int hlen);
+
+int
+dsa_verify(
+    Key *key,
+    unsigned char *signature, int signaturelen,
+    unsigned char *hash, int hlen);
+
+#endif
diff --git a/usr.bin/ssh/hmac.c b/usr.bin/ssh/hmac.c
new file mode 100644
index 00000000000..6d27ebc6a30
--- /dev/null
+++ b/usr.bin/ssh/hmac.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2000 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Markus Friedl.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * 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("$Id: hmac.c,v 1.1 2000/04/03 20:06:15 markus Exp $");
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "getput.h"
+
+#include <ssl/hmac.h>
+
+unsigned char *
+hmac(
+    EVP_MD *evp_md,
+    unsigned int seqno,
+    unsigned char *data, int datalen,
+    unsigned char *key, int keylen)
+{
+	HMAC_CTX c;
+	static unsigned char m[EVP_MAX_MD_SIZE];
+	unsigned char b[4];
+
+	if (key == NULL)
+		fatal("hmac: no key");
+	HMAC_Init(&c, key, keylen, evp_md);
+	PUT_32BIT(b, seqno);
+	HMAC_Update(&c, b, sizeof b);
+	HMAC_Update(&c, data, datalen);
+	HMAC_Final(&c, m, NULL);
+	HMAC_cleanup(&c);
+	return(m);
+}
diff --git a/usr.bin/ssh/hmac.h b/usr.bin/ssh/hmac.h
new file mode 100644
index 00000000000..fb680292739
--- /dev/null
+++ b/usr.bin/ssh/hmac.h
@@ -0,0 +1,11 @@
+#ifndef HMAC_H
+#define HMAC_H
+
+unsigned char *
+hmac(
+    EVP_MD *evp_md,
+    unsigned int seqno,
+    unsigned char *data, int datalen,
+    unsigned char *key, int len);
+
+#endif
diff --git a/usr.bin/ssh/kex.c b/usr.bin/ssh/kex.c
new file mode 100644
index 00000000000..a52af72abf3
--- /dev/null
+++ b/usr.bin/ssh/kex.c
@@ -0,0 +1,392 @@
+/*
+ * Copyright (c) 2000 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Markus Friedl.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * 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("$Id: kex.c,v 1.1 2000/04/03 20:06:15 markus Exp $");
+
+#include "ssh.h"
+#include "ssh2.h"
+#include "xmalloc.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "cipher.h"
+#include "compat.h"
+
+#include <ssl/bn.h>
+#include <ssl/dh.h>
+
+#include <ssl/crypto.h>
+#include <ssl/bio.h>
+#include <ssl/bn.h>
+#include <ssl/dh.h>
+#include <ssl/pem.h>
+
+#include "kex.h"
+
+Buffer *
+kex_init(char *myproposal[PROPOSAL_MAX])
+{
+	char c = 0;
+	unsigned char cookie[16];
+	u_int32_t rand = 0;
+	int i;
+	Buffer *ki = xmalloc(sizeof(*ki));
+	for (i = 0; i < 16; i++) {
+		if (i % 4 == 0)
+			rand = arc4random();
+		cookie[i] = rand & 0xff;
+		rand >>= 8;
+	}
+	buffer_init(ki);
+	buffer_append(ki, (char *)cookie, sizeof cookie);
+	for (i = 0; i < PROPOSAL_MAX; i++)
+		buffer_put_cstring(ki, myproposal[i]);
+	buffer_append(ki, &c, 1); /* boolean   first_kex_packet_follows */
+	buffer_put_int(ki, 0);    /* uint32    0 (reserved for future extension) */
+	return ki;
+}
+
+/* diffie-hellman-group1-sha1 */
+
+DH *
+new_dh_group1()
+{
+	static char *group1 =
+	    "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
+	    "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
+	    "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
+	    "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
+	    "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
+	    "FFFFFFFF" "FFFFFFFF";
+	DH *dh;
+	int ret;
+	dh = DH_new();
+	if(dh == NULL)
+		fatal("DH_new");
+	ret = BN_hex2bn(&dh->p,group1);
+	if(ret<0)
+		fatal("BN_hex2bn");
+	dh->g = BN_new();
+	if(dh->g == NULL)
+		fatal("DH_new g");
+	BN_set_word(dh->g,2);
+	if (DH_generate_key(dh) == 0)
+		fatal("DH_generate_key");
+	return dh;
+}
+
+void
+bignum_print(BIGNUM *b)
+{
+	BN_print_fp(stderr,b);
+}
+
+void
+dump_digest(unsigned char *digest, int len)
+{
+	int i;
+        for (i = 0; i< len; i++){
+                fprintf(stderr, "%02x", digest[i]);
+		if(i%2!=0)
+			fprintf(stderr, " ");
+	}
+        fprintf(stderr, "\n");
+}
+
+unsigned char *
+kex_hash(
+    char *client_version_string,
+    char *server_version_string,
+    char *ckexinit, int ckexinitlen,
+    char *skexinit, int skexinitlen,
+    char *serverhostkeyblob, int sbloblen,
+    BIGNUM *client_dh_pub,
+    BIGNUM *server_dh_pub,
+    BIGNUM *shared_secret)
+{
+	Buffer b;
+	static unsigned char digest[EVP_MAX_MD_SIZE];
+	EVP_MD *evp_md = EVP_sha1();
+	EVP_MD_CTX md;
+
+	buffer_init(&b);
+	buffer_put_string(&b, client_version_string, strlen(client_version_string));
+	buffer_put_string(&b, server_version_string, strlen(server_version_string));
+
+	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
+	buffer_put_int(&b, ckexinitlen+1);
+	buffer_put_char(&b, SSH2_MSG_KEXINIT);
+	buffer_append(&b, ckexinit, ckexinitlen);
+	buffer_put_int(&b, skexinitlen+1);
+	buffer_put_char(&b, SSH2_MSG_KEXINIT);
+	buffer_append(&b, skexinit, skexinitlen);
+
+	buffer_put_string(&b, serverhostkeyblob, sbloblen);
+	buffer_put_bignum2(&b, client_dh_pub);
+	buffer_put_bignum2(&b, server_dh_pub);
+	buffer_put_bignum2(&b, shared_secret);
+	
+#ifdef DEBUG_KEX
+	buffer_dump(&b);
+#endif
+
+	EVP_DigestInit(&md, evp_md);
+	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+	EVP_DigestFinal(&md, digest, NULL);
+
+	buffer_free(&b);
+
+#ifdef DEBUG_KEX
+        dump_digest(digest, evp_md->md_size);
+#endif
+	return digest;
+}
+
+unsigned char *
+derive_key(int id, int need, char unsigned *hash, BIGNUM *shared_secret)
+{
+	Buffer b;
+	EVP_MD *evp_md = EVP_sha1();
+	EVP_MD_CTX md;
+	char c = id;
+	int have;
+	int mdsz = evp_md->md_size;
+	unsigned char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz);
+
+	buffer_init(&b);
+	buffer_put_bignum2(&b, shared_secret);
+
+	EVP_DigestInit(&md, evp_md);
+	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));	/* shared_secret K */
+	EVP_DigestUpdate(&md, hash, mdsz);		/* transport-06 */
+	EVP_DigestUpdate(&md, &c, 1);			/* key id */
+	EVP_DigestUpdate(&md, hash, mdsz);		/* session id */
+	EVP_DigestFinal(&md, digest, NULL);
+
+	/* expand */
+	for (have = mdsz; need > have; have += mdsz) {
+		EVP_DigestInit(&md, evp_md);
+		EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+		EVP_DigestUpdate(&md, hash, mdsz);
+		EVP_DigestUpdate(&md, digest, have);
+		EVP_DigestFinal(&md, digest + have, NULL);
+	}
+	buffer_free(&b);
+#ifdef DEBUG_KEX
+	fprintf(stderr, "Digest '%c'== ", c);
+	dump_digest(digest, need);
+#endif
+	return digest;
+}
+
+#define NKEYS	6
+
+#define	MAX_PROP	20
+#define	SEP	","
+
+char *
+get_match(char *client, char *server)
+{
+	char *sproposals[MAX_PROP];
+	char *p;
+	int i, j, nproposals;
+
+	for ((p = strtok(server, SEP)), i=0; p; (p = strtok(NULL, SEP)), i++) {
+		if (i < MAX_PROP)
+			sproposals[i] = p;
+		else
+			break;
+	}
+	nproposals = i;
+
+	for ((p = strtok(client, SEP)), i=0; p; (p = strtok(NULL, SEP)), i++) {
+		for (j = 0; j < nproposals; j++)
+			if (strcmp(p, sproposals[j]) == 0)
+				return xstrdup(p);
+	}
+	return NULL;
+}
+void
+choose_enc(Enc *enc, char *client, char *server)
+{
+	char *name = get_match(client, server);
+	if (name == NULL)
+		fatal("no matching cipher found: client %s server %s", client, server);
+	enc->type = cipher_number(name);
+
+	switch (enc->type) {
+	case SSH_CIPHER_3DES_CBC:
+		enc->key_len = 24;
+		enc->iv_len = 8;
+		enc->block_size = 8;
+		break;
+	case SSH_CIPHER_BLOWFISH_CBC:
+	case SSH_CIPHER_CAST128_CBC:
+		enc->key_len = 16;
+		enc->iv_len = 8;
+		enc->block_size = 8;
+		break;
+	case SSH_CIPHER_ARCFOUR:
+		enc->key_len = 16;
+		enc->iv_len = 0;
+		enc->block_size = 8;
+		break;
+	default:
+		fatal("unsupported cipher %s", name);
+	}
+	enc->name = name;
+	enc->enabled = 0;
+	enc->iv = NULL;
+	enc->key = NULL;
+}
+void
+choose_mac(Mac *mac, char *client, char *server)
+{
+	char *name = get_match(client, server);
+	if (name == NULL)
+		fatal("no matching mac found: client %s server %s", client, server);
+	if (strcmp(name, "hmac-md5") == 0) {
+		mac->md = EVP_md5();
+	} else if (strcmp(name, "hmac-sha1") == 0) {
+		mac->md = EVP_sha1();
+	} else if (strcmp(name, "hmac-ripemd160@openssh.com") == 0) {
+		mac->md = EVP_ripemd160();
+	} else {
+		fatal("unsupported mac %s", name);
+	}
+	mac->name = name;
+	mac->mac_len = mac->md->md_size;
+	mac->key_len = datafellows ? 16 : mac->mac_len;
+	mac->key = NULL;
+	mac->enabled = 0;
+}
+void
+choose_comp(Comp *comp, char *client, char *server)
+{
+	char *name = get_match(client, server);
+	if (name == NULL)
+		fatal("no matching comp found: client %s server %s", client, server);
+	if (strcmp(name, "zlib") == 0) {
+		comp->type = 1;
+	} else if (strcmp(name, "none") == 0) {
+		comp->type = 0;
+	} else {
+		fatal("unsupported comp %s", name);
+	}
+	comp->name = name;
+}
+void
+choose_kex(Kex *k, char *client, char *server)
+{
+	k->name = get_match(client, server);
+	if (k->name == NULL)
+		fatal("no kex alg");
+    	if (strcmp(k->name, KEX_DH1) != 0)
+		fatal("bad kex alg %s", k->name);
+}
+void
+choose_hostkeyalg(Kex *k, char *client, char *server)
+{
+	k->hostkeyalg = get_match(client, server);
+	if (k->hostkeyalg == NULL)
+		fatal("no hostkey alg");
+	if (strcmp(k->hostkeyalg, KEX_DSS) != 0)
+		fatal("bad hostkey alg %s", k->hostkeyalg);
+}
+
+Kex *
+kex_choose_conf(char *cprop[PROPOSAL_MAX], char *sprop[PROPOSAL_MAX], int server)
+{
+	int i;
+	int mode;
+	int ctos;				/* direction: if true client-to-server */
+	int need;
+	Kex *k;
+
+	k = xmalloc(sizeof(*k));
+	memset(k, 0, sizeof(*k));
+	k->server = server;
+
+	for (mode = 0; mode < MODE_MAX; mode++) {
+		int nenc, nmac, ncomp;
+		ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
+		nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
+		nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
+		ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
+		choose_enc (&k->enc [mode], cprop[nenc],  sprop[nenc]);
+		choose_mac (&k->mac [mode], cprop[nmac],  sprop[nmac]);
+		choose_comp(&k->comp[mode], cprop[ncomp], sprop[ncomp]);
+		log("kex: %s %s %s %s",
+		    ctos ? "client->server" : "server->client",
+		    k->enc[mode].name,
+		    k->mac[mode].name,
+		    k->comp[mode].name);
+	}
+	choose_kex(k, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
+	choose_hostkeyalg(k, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
+	    sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
+	for (i = 0; i < PROPOSAL_MAX; i++) {
+		xfree(cprop[i]);
+		xfree(sprop[i]);
+	}
+	need = 0;
+	for (mode = 0; mode < MODE_MAX; mode++) {
+	    if (need < k->enc[mode].key_len)
+		    need = k->enc[mode].key_len;
+	    if (need < k->enc[mode].iv_len)
+		    need = k->enc[mode].iv_len;
+	    if (need < k->mac[mode].key_len)
+		    need = k->mac[mode].key_len;
+	}
+	/* need runden? */
+#define WE_NEED 32
+	k->we_need = WE_NEED;
+	k->we_need = need;
+	return k;
+}
+
+int
+kex_derive_keys(Kex *k, unsigned char *hash, BIGNUM *shared_secret)
+{
+	int i;
+	int mode;
+	int ctos;
+	unsigned char *keys[NKEYS];
+
+	for (i = 0; i < NKEYS; i++)
+		keys[i] = derive_key('A'+i, k->we_need, hash, shared_secret);
+
+	for (mode = 0; mode < MODE_MAX; mode++) {
+		ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
+		k->enc[mode].iv  = keys[ctos ? 0 : 1];
+		k->enc[mode].key = keys[ctos ? 2 : 3];
+		k->mac[mode].key = keys[ctos ? 4 : 5];
+	}
+	return 0;
+}
diff --git a/usr.bin/ssh/kex.h b/usr.bin/ssh/kex.h
new file mode 100644
index 00000000000..f9e79994888
--- /dev/null
+++ b/usr.bin/ssh/kex.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2000 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Markus Friedl.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * 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.
+ */
+#ifndef KEX_H
+#define KEX_H
+
+#define	KEX_DH1	"diffie-hellman-group1-sha1"
+#define KEX_DSS	"ssh-dss"
+
+enum kex_init_proposals {
+	PROPOSAL_KEX_ALGS,
+	PROPOSAL_SERVER_HOST_KEY_ALGS,
+	PROPOSAL_ENC_ALGS_CTOS,
+	PROPOSAL_ENC_ALGS_STOC,
+	PROPOSAL_MAC_ALGS_CTOS,
+	PROPOSAL_MAC_ALGS_STOC,
+	PROPOSAL_COMP_ALGS_CTOS,
+	PROPOSAL_COMP_ALGS_STOC,
+	PROPOSAL_LANG_CTOS,
+	PROPOSAL_LANG_STOC,
+	PROPOSAL_MAX
+};
+
+enum kex_modes {
+	MODE_IN,
+	MODE_OUT,
+	MODE_MAX
+};
+
+typedef struct Kex Kex;
+typedef struct Mac Mac;
+typedef struct Comp Comp;
+typedef struct Enc Enc;
+
+struct Enc {
+	int		type;
+	int		enabled;
+	int		block_size;
+	unsigned char	*key;
+	unsigned char	*iv;
+	int		key_len;
+	int		iv_len;
+	char		*name;
+};
+struct Mac {
+	EVP_MD		*md;
+	int		enabled;
+	int		mac_len;
+	unsigned char	*key;
+	int		key_len;
+	char		*name;
+};
+struct Comp {
+	int		type;
+	int		enabled;
+	char		*name;
+};
+struct Kex {
+	Enc		enc [MODE_MAX];
+	Mac		mac [MODE_MAX];
+	Comp		comp[MODE_MAX];
+	int		we_need;
+	int		server;
+	char		*name;
+	char		*hostkeyalg;
+};
+
+Buffer	*kex_init(char *myproposal[PROPOSAL_MAX]);
+DH	*new_dh_group1();
+Kex 	*kex_choose_conf(char *cprop[PROPOSAL_MAX], char *sprop[PROPOSAL_MAX], int server);
+int	kex_derive_keys(Kex *k, unsigned char *hash, BIGNUM *shared_secret);
+void	bignum_print(BIGNUM *b);
+void	packet_set_kex(Kex *k);
+
+unsigned char *
+kex_hash(
+    char *client_version_string,
+    char *server_version_string,
+    char *ckexinit, int ckexinitlen,
+    char *skexinit, int skexinitlen,
+    char *serverhostkeyblob, int sbloblen,
+    BIGNUM *client_dh_pub,
+    BIGNUM *server_dh_pub,
+    BIGNUM *shared_secret);
+
+#endif
diff --git a/usr.bin/ssh/lib/Makefile b/usr.bin/ssh/lib/Makefile
index 262273cc35c..4c695afa741 100644
--- a/usr.bin/ssh/lib/Makefile
+++ b/usr.bin/ssh/lib/Makefile
@@ -5,7 +5,7 @@ SRCS=   authfd.c authfile.c bufaux.c buffer.c canohost.c channels.c \
 	cipher.c compat.c compress.c crc32.c deattack.c fingerprint.c \
 	hostfile.c log.c match.c mpaux.c nchan.c packet.c readpass.c \
 	rsa.c tildexpand.c ttymodes.c uidswap.c xmalloc.c atomicio.c \
-	key.c dispatch.c
+	key.c dispatch.c dsa.c kex.c hmac.c
 
 NOPROFILE= yes
 NOPIC=	yes