From f9b78852379b74a2d14e6fc94fe52af30b7e9c31 Mon Sep 17 00:00:00 2001 From: "djm@openbsd.org" Date: Thu, 26 Mar 2015 07:00:04 +0000 Subject: upstream commit ban all-zero curve25519 keys as recommended by latest CFRG curves draft; ok markus --- kexc25519.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kexc25519.c b/kexc25519.c index b6e6c4010..8d8cd4a2b 100644 --- a/kexc25519.c +++ b/kexc25519.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kexc25519.c,v 1.8 2015/01/19 20:16:15 markus Exp $ */ +/* $OpenBSD: kexc25519.c,v 1.9 2015/03/26 07:00:04 djm Exp $ */ /* * Copyright (c) 2001, 2013 Markus Friedl. All rights reserved. * Copyright (c) 2010 Damien Miller. All rights reserved. @@ -66,6 +66,11 @@ kexc25519_shared_key(const u_char key[CURVE25519_SIZE], u_char shared_key[CURVE25519_SIZE]; int r; + /* Check for all-zero public key */ + explicit_bzero(shared_key, CURVE25519_SIZE); + if (timingsafe_bcmp(pub, shared_key, CURVE25519_SIZE) == 0) + return SSH_ERR_KEY_INVALID_EC_VALUE; + crypto_scalarmult_curve25519(shared_key, key, pub); #ifdef DEBUG_KEXECDH dump_digest("shared secret", shared_key, CURVE25519_SIZE); -- cgit v1.2.3