From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C392BC4363A for ; Sun, 25 Oct 2020 14:31:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 916B5208E4 for ; Sun, 25 Oct 2020 14:31:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1416635AbgJYOb2 (ORCPT ); Sun, 25 Oct 2020 10:31:28 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:40120 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1414677AbgJYOb2 (ORCPT ); Sun, 25 Oct 2020 10:31:28 -0400 Received: by mail-qt1-f196.google.com with SMTP id m9so4899089qth.7; Sun, 25 Oct 2020 07:31:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bi7rG0H94VO76zPLa4Hh0/sN75asB3cy5CcRjg5R6zI=; b=nyp0VgarkLXREJjtBpcWE0kZDqvPQ0R2yuPDrRgGg2lEClPv/Slonlc94thftyEBHV pwHUqAjSix+ap5kdAfn1YGOeI19gBHm2vru48ThN9OfE8RqbzbcQBO9D05qdGXf3jptG 1HQGULOuHNGncGYDyMEuxFTmFqa2nDcVfOaNv7NhyS9p4SnaA1d2+gZZNHsR50iNZv5x w3tRu6XRVaVOaHdChrKovEl5n/THltSuE28ZBBO3tmPJ2oOju2RTsKXvvrS8eRPLV1fJ lLnD8T/a/ZQlVJwwAHsjjdkRk8PYEx6eCHFd2KDb2Yqq6usLwZuztS1jYgv+uhcaShRk lgOw== X-Gm-Message-State: AOAM531tKJupFq/8CXE+PD/M+n4tLdrMnYmgFyOMwOFs93Hrrdi9B1Yt u4Kh4Y4GEMQWtbYfnFNKX1Q= X-Google-Smtp-Source: ABdhPJy6TJ7OnnPMnOVBY7QpOsC5dVA//baSaIV9SoClXC96369xl8GnFioUvT3jfKCGp6Xr8IyUnw== X-Received: by 2002:a05:622a:242:: with SMTP id c2mr12600299qtx.230.1603636287091; Sun, 25 Oct 2020 07:31:27 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id s73sm4740898qke.71.2020.10.25.07.31.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Oct 2020 07:31:26 -0700 (PDT) From: Arvind Sankar To: Herbert Xu , "David S. Miller" , "linux-crypto@vger.kernel.org" , Eric Biggers , David Laight Cc: linux-kernel@vger.kernel.org, Eric Biggers Subject: [PATCH v4 4/6] crypto: lib/sha256 - Clear W[] in sha256_update() instead of sha256_transform() Date: Sun, 25 Oct 2020 10:31:17 -0400 Message-Id: <20201025143119.1054168-5-nivedita@alum.mit.edu> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201025143119.1054168-1-nivedita@alum.mit.edu> References: <20201025143119.1054168-1-nivedita@alum.mit.edu> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The temporary W[] array is currently zeroed out once every call to sha256_transform(), i.e. once every 64 bytes of input data. Moving it to sha256_update() instead so that it is cleared only once per update can save about 2-3% of the total time taken to compute the digest, with a reasonable memset() implementation, and considerably more (~20%) with a bad one (eg the x86 purgatory currently uses a memset() coded in C). Signed-off-by: Arvind Sankar Reviewed-by: Eric Biggers --- lib/crypto/sha256.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c index 099cd11f83c1..c6bfeacc5b81 100644 --- a/lib/crypto/sha256.c +++ b/lib/crypto/sha256.c @@ -43,10 +43,9 @@ static inline void BLEND_OP(int I, u32 *W) W[I] = s1(W[I-2]) + W[I-7] + s0(W[I-15]) + W[I-16]; } -static void sha256_transform(u32 *state, const u8 *input) +static void sha256_transform(u32 *state, const u8 *input, u32 *W) { u32 a, b, c, d, e, f, g, h, t1, t2; - u32 W[64]; int i; /* load the input */ @@ -200,15 +199,13 @@ static void sha256_transform(u32 *state, const u8 *input) state[0] += a; state[1] += b; state[2] += c; state[3] += d; state[4] += e; state[5] += f; state[6] += g; state[7] += h; - - /* clear any sensitive info... */ - memzero_explicit(W, 64 * sizeof(u32)); } void sha256_update(struct sha256_state *sctx, const u8 *data, unsigned int len) { unsigned int partial, done; const u8 *src; + u32 W[64]; partial = sctx->count & 0x3f; sctx->count += len; @@ -223,11 +220,13 @@ void sha256_update(struct sha256_state *sctx, const u8 *data, unsigned int len) } do { - sha256_transform(sctx->state, src); + sha256_transform(sctx->state, src, W); done += 64; src = data + done; } while (done + 63 < len); + memzero_explicit(W, sizeof(W)); + partial = 0; } memcpy(sctx->buf + partial, src, len - done); -- 2.26.2