From 4d8ec289925e296c40f515cfd82d215f00addf8f Mon Sep 17 00:00:00 2001 From: tb Date: Sun, 2 Sep 2018 17:20:31 +0000 Subject: [PATCH] Elliptic curve arithmetic only makes sense between points that belong to the same curve. Some Wycheproof tests violate this assumption, making ECDH_compute_key() compute and return garbage. Check that pub_key lies on the curve of the private key so that the calculations make sense. Most paths that get here have this checked (in particular those from OpenSSH and libssl), but one might get here after using d2i_* or manual computation. discussed with & ok jsing; "good catch!" markus --- lib/libcrypto/ecdh/ech_key.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/libcrypto/ecdh/ech_key.c b/lib/libcrypto/ecdh/ech_key.c index 5c2dc70b632..6911f1e3419 100644 --- a/lib/libcrypto/ecdh/ech_key.c +++ b/lib/libcrypto/ecdh/ech_key.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ech_key.c,v 1.7 2017/01/29 17:49:23 beck Exp $ */ +/* $OpenBSD: ech_key.c,v 1.8 2018/09/02 17:20:31 tb Exp $ */ /* ==================================================================== * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. * @@ -125,6 +125,10 @@ ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, } group = EC_KEY_get0_group(ecdh); + + if (!EC_POINT_is_on_curve(group, pub_key, ctx)) + goto err; + if ((tmp = EC_POINT_new(group)) == NULL) { ECDHerror(ERR_R_MALLOC_FAILURE); goto err; -- 2.20.1