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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 3F325C7618F for ; Fri, 19 Jul 2019 01:47:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 147742084C for ; Fri, 19 Jul 2019 01:47:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726092AbfGSBrk (ORCPT ); Thu, 18 Jul 2019 21:47:40 -0400 Received: from helcar.hmeau.com ([216.24.177.18]:38846 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbfGSBrk (ORCPT ); Thu, 18 Jul 2019 21:47:40 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1hoHzg-0004m2-W8; Fri, 19 Jul 2019 09:47:33 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1hoHza-0007Nw-NB; Fri, 19 Jul 2019 09:47:26 +0800 Date: Fri, 19 Jul 2019 09:47:26 +0800 From: Herbert Xu To: Pascal Van Leeuwen Cc: Milan Broz , Ard Biesheuvel , Horia Geanta , "linux-crypto@vger.kernel.org" , "dm-devel@redhat.com" Subject: Re: xts fuzz testing and lack of ciphertext stealing support Message-ID: <20190719014726.erp3bf26oi4rducm@gondor.apana.org.au> References: <20190718065223.4xaefcwjoxvujntw@gondor.apana.org.au> <20190718072154.m2umem24x4grbf6w@gondor.apana.org.au> <36e78459-1594-6d19-0ab4-95b03a6de036@gmail.com> <20190718152908.xiuze3kb3fdc7ov6@gondor.apana.org.au> <20190718155140.b6ig3zq22askmfpy@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Thu, Jul 18, 2019 at 04:35:26PM +0000, Pascal Van Leeuwen wrote: > > Tthen there's still the issue of advancing that last tweak. From what I've seen, > the xts implementation does not output the last tweak so you would have to > recompute it locally in cts.c as block_cipher_enc(iv) * alpha^j. Which is wasteful. > Of course this could be solved by redefining xts to output the last tweak > like CBC/CTR output their last IV ... Which would probably give us HW guys > trouble again because our HW cannot do *that* ... (While the HW very likely > *does* implement the cipher text stealing properly, just to be able to boast > about IEEE P1619 compliance ...) If your hardware supports XTS properly then you wouldn't even need to use this new template. You would directly export the xts interface. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt