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From: "Stephan Müller" <smueller@chronox.de>
To: herbert@gondor.apana.org.au
Cc: linux-crypto@vger.kernel.org,
	Marcelo Cerri <marcelo.cerri@canonical.com>,
	Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Subject: [PATCH 1/3] crypto: ECDH - check validity of Z before export
Date: Fri, 10 Jul 2020 12:10:07 +0200
Message-ID: <5377091.DvuYhMxLoT@positron.chronox.de> (raw)
In-Reply-To: <2543601.mvXUDI8C0e@positron.chronox.de>

From 5385865b3f44d331f91c6786a2e7f4e2fb4d8cb2 Mon Sep 17 00:00:00 2001
From: Stephan Mueller <stephan.mueller@atsec.com>
Date: Thu, 11 Jun 2020 08:12:54 +0200
Subject: 

SP800-56A rev3 section 5.7.1.2 step 2 mandates that the validity of the
calculated shared secret is verified before the data is returned to the
caller. Thus, the export function and the validity check functions are
reversed. In addition, the sensitive variables of priv and rand_z are
zeroized.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/ecc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index 02d35be7702b..52e2d49262f2 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1495,11 +1495,16 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
 
 	ecc_point_mult(product, pk, priv, rand_z, curve, ndigits);
 
-	ecc_swap_digits(product->x, secret, ndigits);
-
-	if (ecc_point_is_zero(product))
+	if (ecc_point_is_zero(product)) {
 		ret = -EFAULT;
+		goto err_validity;
+	}
+
+	ecc_swap_digits(product->x, secret, ndigits);
 
+err_validity:
+	memzero_explicit(priv, sizeof(priv));
+	memzero_explicit(rand_z, sizeof(rand_z));
 	ecc_free_point(product);
 err_alloc_product:
 	ecc_free_point(pk);
-- 
2.26.2





  reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-10 10:09 [PATCH 0/3] DH: SP800-56A rev 3 compliant shared secret Stephan Müller
2020-07-10 10:10 ` Stephan Müller [this message]
2020-07-10 10:10 ` [PATCH 2/3] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-10 14:42   ` Ard Biesheuvel
2020-07-10 15:10     ` Stephan Mueller
2020-07-10 10:15 ` [PATCH 3/3] crypto: DH - check validity of Z before export Stephan Müller
2020-07-12 16:38 ` [PATCH v2 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-12 16:39   ` [PATCH v2 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-12 18:02     ` Vitaly Chikunov
2020-07-15 13:17     ` Marcelo Henrique Cerri
2020-07-12 16:39   ` [PATCH v2 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-16  7:30     ` Herbert Xu
2020-07-16  8:41       ` Ard Biesheuvel
2020-07-16 12:50         ` Marcelo Henrique Cerri
2020-07-16 13:09           ` Ard Biesheuvel
2020-07-16 13:41             ` Marcelo Henrique Cerri
2020-07-16 13:53               ` Ard Biesheuvel
2020-07-16 14:23                 ` Marcelo Henrique Cerri
2020-07-16 14:37                   ` Ard Biesheuvel
2020-07-16 14:56                     ` Marcelo Henrique Cerri
2020-07-16 15:20                       ` Ard Biesheuvel
2020-07-12 16:40   ` [PATCH v2 3/5] crypto: DH - check validity of Z before export Stephan Müller
2020-07-15 13:17     ` Marcelo Henrique Cerri
2020-07-12 16:40   ` [PATCH v2 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-15 13:18     ` Marcelo Henrique Cerri
2020-07-12 16:42   ` [PATCH v2 5/5] crypto: ECDH " Stephan Müller
2020-07-12 18:06     ` Vitaly Chikunov
2020-07-13  5:04       ` Stephan Mueller
2020-07-13  5:59         ` Vitaly Chikunov
2020-07-13  6:02           ` Stephan Müller
2020-07-15 13:19     ` Marcelo Henrique Cerri
2020-07-20 17:05   ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-20 17:07     ` [PATCH v3 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-22 13:11       ` Vitaly Chikunov
2020-07-24 17:47       ` Neil Horman
2020-07-20 17:08     ` [PATCH v3 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-20 17:08     ` [PATCH v3 3/5] crypto: DH - check validity of Z before export Stephan Müller
2020-07-24 18:02       ` Neil Horman
2020-07-20 17:08     ` [PATCH v3 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-20 17:09     ` [PATCH v3 5/5] crypto: ECDH " Stephan Müller
2020-07-21 11:35     ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Marcelo Henrique Cerri
2020-07-31 13:29     ` Herbert Xu

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