- 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 225e65592..26c8cdfd6 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);
 }