From patchwork Sun Nov 4 13:34:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Chikunov X-Patchwork-Id: 10666869 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CFD4A175A for ; Sun, 4 Nov 2018 13:34:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B340C296B1 for ; Sun, 4 Nov 2018 13:34:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A643D296D0; Sun, 4 Nov 2018 13:34:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 93A0F296B1 for ; Sun, 4 Nov 2018 13:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728914AbeKDWtg (ORCPT ); Sun, 4 Nov 2018 17:49:36 -0500 Received: from vmicros1.altlinux.org ([194.107.17.57]:44590 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728897AbeKDWtg (ORCPT ); Sun, 4 Nov 2018 17:49:36 -0500 Received: from imap.altlinux.org (imap.altlinux.org [194.107.17.38]) by vmicros1.altlinux.org (Postfix) with ESMTP id 28A6572CC68; Sun, 4 Nov 2018 16:34:32 +0300 (MSK) Received: from beacon.altlinux.org (unknown [185.6.174.98]) by imap.altlinux.org (Postfix) with ESMTPSA id 0227D4A4A29; Sun, 4 Nov 2018 16:34:31 +0300 (MSK) From: Vitaly Chikunov To: Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Vitaly Chikunov Subject: [PATCH] crypto: ecc - regularize scalar for scalar multiplication Date: Sun, 4 Nov 2018 16:34:20 +0300 Message-Id: <20181104133420.15783-1-vt@altlinux.org> X-Mailer: git-send-email 2.11.0 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP ecc_point_mult is supposed to be used with a regularized scalar, otherwise, it's possible to deduce the position of the top bit of the scalar with timing attack. ecc_point_mult is already using a regular algorithm (i.e. having an operation flow independent of the input scalar) but regularization step is forgotten. Regularization step is based on micro-ecc by Kenneth MacKay. Signed-off-by: Vitaly Chikunov --- crypto/ecc.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/crypto/ecc.c b/crypto/ecc.c index 8facafd67802..adcce310f646 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -842,15 +842,23 @@ static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2, u64 *curve_prime, static void ecc_point_mult(struct ecc_point *result, const struct ecc_point *point, const u64 *scalar, - u64 *initial_z, u64 *curve_prime, + u64 *initial_z, const struct ecc_curve *curve, unsigned int ndigits) { /* R0 and R1 */ u64 rx[2][ECC_MAX_DIGITS]; u64 ry[2][ECC_MAX_DIGITS]; u64 z[ECC_MAX_DIGITS]; + u64 sk[2][ECC_MAX_DIGITS]; + u64 *curve_prime = curve->p; int i, nb; - int num_bits = vli_num_bits(scalar, ndigits); + int num_bits; + int carry; + + carry = vli_add(sk[0], scalar, curve->n, ndigits); + vli_add(sk[1], sk[0], curve->n, ndigits); + scalar = sk[!carry]; + num_bits = sizeof(u64) * ndigits * 8 + 1; vli_set(rx[1], point->x, ndigits); vli_set(ry[1], point->y, ndigits); @@ -1004,7 +1012,7 @@ int ecc_make_pub_key(unsigned int curve_id, unsigned int ndigits, goto out; } - ecc_point_mult(pk, &curve->g, priv, NULL, curve->p, ndigits); + ecc_point_mult(pk, &curve->g, priv, NULL, curve, ndigits); if (ecc_point_is_zero(pk)) { ret = -EAGAIN; goto err_free_point; @@ -1090,7 +1098,7 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, goto err_alloc_product; } - ecc_point_mult(product, pk, priv, rand_z, curve->p, ndigits); + ecc_point_mult(product, pk, priv, rand_z, curve, ndigits); ecc_swap_digits(product->x, secret, ndigits);