- djm@cvs.openbsd.org 2005/11/04 05:15:59

     [kex.c kex.h kexdh.c kexdhc.c kexdhs.c kexgex.c kexgexc.c kexgexs.c]
     remove hardcoded hash lengths in key exchange code, allowing
     implementation of KEX methods with different hashes (e.g. SHA-256);
     ok markus@ dtucker@ stevesk@

1 files changed, 10 insertions, 7 deletions

diff --git a/kexgexc.c b/kexgexc.c
index 0193183b..a6ff8757 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -24,7 +24,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexgexc.c,v 1.2 2003/12/08 11:00:47 markus Exp $");
+RCSID("$OpenBSD: kexgexc.c,v 1.3 2005/11/04 05:15:59 djm Exp $");
 
 #include "xmalloc.h"
 #include "key.h"
@@ -42,7 +42,7 @@ kexgex_client(Kex *kex)
 	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;
+	u_int klen, kout, slen, sbloblen, hashlen;
 	int min, max, nbits;
 	DH *dh;
 
@@ -155,7 +155,8 @@ kexgex_client(Kex *kex)
 		min = max = -1;
 
 	/* calc and verify H */
-	hash = kexgex_hash(
+	kexgex_hash(
+	    kex->evp_md,
 	    kex->client_version_string,
 	    kex->server_version_string,
 	    buffer_ptr(&kex->my), buffer_len(&kex->my),
@@ -165,25 +166,27 @@ kexgex_client(Kex *kex)
 	    dh->p, dh->g,
 	    dh->pub_key,
 	    dh_server_pub,
-	    shared_secret
+	    shared_secret,
+	    &hash, &hashlen
 	);
+
 	/* 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)
+	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 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_len = hashlen;
 		kex->session_id = xmalloc(kex->session_id_len);
 		memcpy(kex->session_id, hash, kex->session_id_len);
 	}
-	kex_derive_keys(kex, hash, shared_secret);
+	kex_derive_keys(kex, hash, hashlen, shared_secret);
 	BN_clear_free(shared_secret);
 
 	kex_finish(kex);