- 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, 8 insertions, 9 deletions

diff --git a/kexdhs.c b/kexdhs.c
index 225e6559..26c8cdfd 100644
--- a/kexdhs.c
+++ b/kexdhs.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexdhs.c,v 1.2 2004/06/13 12:53:24 djm Exp $");
+RCSID("$OpenBSD: kexdhs.c,v 1.3 2005/11/04 05:15:59 djm Exp $");
 
 #include "xmalloc.h"
 #include "key.h"
@@ -41,7 +41,7 @@ kexdh_server(Kex *kex)
 	DH *dh;
 	Key *server_host_key;
 	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
-	u_int sbloblen, klen, kout;
+	u_int sbloblen, klen, kout, hashlen;
 	u_int slen;
 
 	/* generate server DH public key */
@@ -103,7 +103,7 @@ kexdh_server(Kex *kex)
 	key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
 
 	/* calc H */
-	hash = kex_dh_hash(
+	kex_dh_hash(
 	    kex->client_version_string,
 	    kex->server_version_string,
 	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
@@ -111,21 +111,20 @@ kexdh_server(Kex *kex)
 	    server_host_key_blob, sbloblen,
 	    dh_client_pub,
 	    dh->pub_key,
-	    shared_secret
+	    shared_secret,
+	    &hash, &hashlen
 	);
 	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_len = hashlen;
 		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));
+	PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, hashlen));
 
 	/* destroy_sensitive_data(); */
 
@@ -141,7 +140,7 @@ kexdh_server(Kex *kex)
 	/* have keys, free DH */
 	DH_free(dh);
 
-	kex_derive_keys(kex, hash, shared_secret);
+	kex_derive_keys(kex, hash, hashlen, shared_secret);
 	BN_clear_free(shared_secret);
 	kex_finish(kex);
 }