From: jsing <jsing@openbsd.org>
Date: Tue, 14 Feb 2023 18:01:15 +0000 (+0000)
Subject: Make BN_set_negative() closer to constant time.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=7e3e74b6aafd8c09abf059035860ee6ea3745a52;p=openbsd

Make BN_set_negative() closer to constant time.

ok tb@
---

diff --git a/lib/libcrypto/bn/bn_lib.c b/lib/libcrypto/bn/bn_lib.c
index e00909bb3ba..32ac7ae606e 100644
--- a/lib/libcrypto/bn/bn_lib.c
+++ b/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.73 2023/02/13 04:03:38 jsing Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.74 2023/02/14 18:01:15 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -66,6 +66,7 @@
 #include <openssl/err.h>
 
 #include "bn_local.h"
+#include "bn_internal.h"
 
 BIGNUM *
 BN_new(void)
@@ -730,7 +731,7 @@ BN_mask_bits(BIGNUM *a, int n)
 void
 BN_set_negative(BIGNUM *bn, int neg)
 {
-	bn->neg = (neg != 0) && !BN_is_zero(bn);
+	bn->neg = ~BN_is_zero(bn) & bn_ct_ne_zero(neg);
 }
 
 int