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=-15.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1A669C07E99 for ; Fri, 9 Jul 2021 13:55:28 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A843261208 for ; Fri, 9 Jul 2021 13:55:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A843261208 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43582 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m1qyU-0006dg-HJ for qemu-devel@archiver.kernel.org; Fri, 09 Jul 2021 09:55:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41738) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m1qxn-0005z9-L5 for qemu-devel@nongnu.org; Fri, 09 Jul 2021 09:54:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:57226) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m1qxj-0005Vp-8s for qemu-devel@nongnu.org; Fri, 09 Jul 2021 09:54:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625838877; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yDU/GjTUJQv4aQ6ZITCJHY6f9CVksz0DqdhDVvwtPdk=; b=bxpZuJ1Q9IP8wwNnh2SOozkFrJBNW5QUUxLUemUXZT0FxZ3wGjNXMspVIZTzdH8Fjv8+TK X8XaXXcx4NdwndfTVz5NXeCtCf55uMkX7RAuDa/q/GKi8nWzArt+7L7V+WKQpCxsH0jOeG 5Fp3p5ufa5YOjovQHylVi4P0R5xiets= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-121-065iDWkhPoyA1XzGnq8bvA-1; Fri, 09 Jul 2021 09:54:33 -0400 X-MC-Unique: 065iDWkhPoyA1XzGnq8bvA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A7913804300 for ; Fri, 9 Jul 2021 13:54:32 +0000 (UTC) Received: from redhat.com (ovpn-114-175.ams2.redhat.com [10.36.114.175]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0D2965D6A8; Fri, 9 Jul 2021 13:54:27 +0000 (UTC) Date: Fri, 9 Jul 2021 14:53:56 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Eric Blake Subject: Re: [PATCH 08/18] crypto: add crypto tests for single block DES-ECB and DES-CBC Message-ID: References: <20210706095924.764117-1-berrange@redhat.com> <20210706095924.764117-9-berrange@redhat.com> <20210708185054.gec3r7novpn7ogzm@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210708185054.gec3r7novpn7ogzm@redhat.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.45, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Markus Armbruster , qemu-devel@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jul 08, 2021 at 01:50:54PM -0500, Eric Blake wrote: > On Tue, Jul 06, 2021 at 10:59:14AM +0100, Daniel P. Berrangé wrote: > > The GNUTLS crypto provider doesn't support DES-ECB, only DES-CBC. > > I had to go research these terms; DES-ECB is weaker (each block > encrypted on its own), DES-CBC is stronger (the encryption of later > blocks depend on the earlier text). Makes sense that GNUTLS has > dropped support for the weaker form. > > > We can use the latter to simulate the former, if we encrypt only > > 1 block (8 bytes) of data at a time, using a all-zeros IV. This > > using an all-zeros > > > is a very inefficient way to use the QCryptoCipher APIs, but > > since the VNC authentication challenge is only 16 bytes, this > > is acceptable. No other part of QEMU should be using DES. This > > test case demonstrates the equivalence of ECB and CBC for the > > single-block case. > > Agreed - both on the inefficiency (we're throwing away all the work > spent on chaining the later blocks - thankfully there is only one such > block in our 16-byte challenge), and on the fact that DES should be > avoided where possible (our sole use is due to VNC's less-than-stellar > "security"). Actually there isn't any work wasted chaining blocks, because we're only writing one block of data. The inefficiency is because we have to constantly re-create the cipher context object after every 8 bytes. This massively dominates over the cipher speed. > > > > > Signed-off-by: Daniel P. Berrangé > > --- > > tests/unit/test-crypto-cipher.c | 23 +++++++++++++++++++++++ > > 1 file changed, 23 insertions(+) > > Reviewed-by: Eric Blake Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|