- djm@cvs.openbsd.org 2014/01/12 08:13:13

     [bufaux.c buffer.h kex.c kex.h kexc25519.c kexc25519c.c kexc25519s.c]
     [kexdhc.c kexdhs.c kexecdhc.c kexecdhs.c kexgexc.c kexgexs.c]
     avoid use of OpenSSL BIGNUM type and functions for KEX with
     Curve25519 by adding a buffer_put_bignum2_from_string() that stores
     a string using the bignum encoding rules. Will make it easier to
     build a reduced-feature OpenSSH without OpenSSL in the future;
     ok markus@

1 files changed, 8 insertions, 7 deletions

diff --git a/kexc25519c.c b/kexc25519c.c
index 4655c2542..a80678af6 100644
--- a/kexc25519c.c
+++ b/kexc25519c.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexc25519c.c,v 1.3 2014/01/09 23:20:00 djm Exp $ */
+/* $OpenBSD: kexc25519c.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -45,7 +45,6 @@
 void
 kexc25519_client(Kex *kex)
 {
-        BIGNUM *shared_secret;
         Key *server_host_key;
         u_char client_key[CURVE25519_SIZE];
         u_char client_pubkey[CURVE25519_SIZE];
@@ -53,6 +52,7 @@ kexc25519_client(Kex *kex)
         u_char *server_host_key_blob = NULL, *signature = NULL;
         u_char *hash;
         u_int slen, sbloblen, hashlen;
+        Buffer shared_secret;
 
         kexc25519_keygen(client_key, client_pubkey);
 
@@ -93,7 +93,8 @@ kexc25519_client(Kex *kex)
         signature = packet_get_string(&slen);
         packet_check_eom();
 
-        shared_secret = kexc25519_shared_key(client_key, server_pubkey);
+        buffer_init(&shared_secret);
+        kexc25519_shared_key(client_key, server_pubkey, &shared_secret);
 
         /* calc and verify H */
         kex_c25519_hash(
@@ -105,7 +106,7 @@ kexc25519_client(Kex *kex)
             server_host_key_blob, sbloblen,
             client_pubkey,
             server_pubkey,
-            shared_secret,
+            buffer_ptr(&shared_secret), buffer_len(&shared_secret),
             &hash, &hashlen
         );
         free(server_host_key_blob);
@@ -121,8 +122,8 @@ kexc25519_client(Kex *kex)
                 kex->session_id = xmalloc(kex->session_id_len);
                 memcpy(kex->session_id, hash, kex->session_id_len);
         }
-
-        kex_derive_keys(kex, hash, hashlen, shared_secret);
-        BN_clear_free(shared_secret);
+        kex_derive_keys(kex, hash, hashlen,
+            buffer_ptr(&shared_secret), buffer_len(&shared_secret));
+        buffer_free(&shared_secret);
         kex_finish(kex);
 }