From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753619AbbLFBwI (ORCPT ); Sat, 5 Dec 2015 20:52:08 -0500 Received: from frisell.zx2c4.com ([192.95.5.64]:40064 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752756AbbLFBv7 (ORCPT ); Sat, 5 Dec 2015 20:51:59 -0500 From: "Jason A. Donenfeld" To: herbert@gondor.apana.org.au, davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Netdev , martin@strongswan.org Cc: "Jason A. Donenfeld" , stable@vger.kernel.org Subject: [PATCH 2/2] chacha20poly1305: Skip encryption/decryption for 0-len Date: Sun, 6 Dec 2015 02:51:38 +0100 Message-Id: <1449366698-2422-2-git-send-email-Jason@zx2c4.com> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1449366698-2422-1-git-send-email-Jason@zx2c4.com> References: <1449366698-2422-1-git-send-email-Jason@zx2c4.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the length of the plaintext is zero, there's no need to waste cycles on encryption and decryption. Using the chacha20poly1305 construction for zero-length plaintexts is a common way of using a shared encryption key for AAD authentication. Signed-off-by: Jason A. Donenfeld Cc: --- crypto/chacha20poly1305.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c index 99c3cce..7b6b935 100644 --- a/crypto/chacha20poly1305.c +++ b/crypto/chacha20poly1305.c @@ -130,6 +130,9 @@ static int chacha_decrypt(struct aead_request *req) struct scatterlist *src, *dst; int err; + if (rctx->cryptlen == 0) + goto skip; + chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); @@ -150,6 +153,7 @@ static int chacha_decrypt(struct aead_request *req) if (err) return err; +skip: return poly_verify_tag(req); } @@ -415,6 +419,9 @@ static int chacha_encrypt(struct aead_request *req) struct scatterlist *src, *dst; int err; + if (req->cryptlen == 0) + goto skip; + chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); @@ -435,6 +442,7 @@ static int chacha_encrypt(struct aead_request *req) if (err) return err; +skip: return poly_genkey(req); } -- 2.6.3