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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 865FBC433FE for ; Fri, 4 Dec 2020 16:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5475622287 for ; Fri, 4 Dec 2020 16:04:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730738AbgLDQE3 (ORCPT ); Fri, 4 Dec 2020 11:04:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728355AbgLDQE3 (ORCPT ); Fri, 4 Dec 2020 11:04:29 -0500 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 074A7C0613D1; Fri, 4 Dec 2020 08:03:49 -0800 (PST) Received: by fieldses.org (Postfix, from userid 2815) id DF8FC6F73; Fri, 4 Dec 2020 11:03:47 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org DF8FC6F73 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1607097827; bh=ERIkl1BDXlF5O6syA29Bwhswr1FuTLeR381zvqC+rxM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b1JQi9U80NaedGr7RHRaQCnG5xEb1uwUKyGuRYMKooN+bXDIHFlQ/Cln4KMm+3YMB 2RA6oh05GDlF4ZCKlCkKbUcS+97xKciT+0QrSFC4ldMYSkYip8ldKOr/vTiipIM9RZ eVl7dWRSgWW1tfpFPNJL17gbMtkai9ahTAXcshoQ= Date: Fri, 4 Dec 2020 11:03:47 -0500 From: Bruce Fields To: David Howells Cc: Chuck Lever , CIFS , Linux NFS Mailing List , Herbert Xu , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Trond Myklebust , linux-crypto@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org Subject: Re: Why the auxiliary cipher in gss_krb5_crypto.c? Message-ID: <20201204160347.GA26933@fieldses.org> References: <20201204154626.GA26255@fieldses.org> <2F96670A-58DC-43A6-A20E-696803F0BFBA@oracle.com> <160518586534.2277919.14475638653680231924.stgit@warthog.procyon.org.uk> <118876.1607093975@warthog.procyon.org.uk> <122997.1607097713@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <122997.1607097713@warthog.procyon.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04, 2020 at 04:01:53PM +0000, David Howells wrote: > Bruce Fields wrote: > > > > Reading up on CTS, I'm guessing the reason it's like this is that CTS is the > > > same as the non-CTS, except for the last two blocks, but the non-CTS one is > > > more efficient. > > > > CTS is cipher-text stealing, isn't it? I think it was Kevin Coffman > > that did that, and I don't remember the history. I thought it was > > required by some spec or peer implementation (maybe Windows?) but I > > really don't remember. It may predate git. I'll dig around and see > > what I can find. > > rfc3961 and rfc3962 specify CTS-CBC with AES. OK, I guess I don't understand the question. I haven't thought about this code in at least a decade. What's an auxilary cipher? Is this a question about why we're implementing something, or how we're implementing it? --b.