- 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 0193183b9..a6ff8757d 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);