IETF Logo Mail Archive

Re: Fixing exchange of host keys in the SSH key exchange

Peter Gutmann <pgut001@cs.auckland.ac.nz> Sat, 25 March 2017 09:57 UTC

Return-Path: <bounces-ietf-ssh-owner-secsh-tyoxbijeg7-archive=lists.ietf.org@NetBSD.org>
X-Original-To: ietfarch-secsh-tyoxbijeg7-archive@ietfa.amsl.com
Delivered-To: ietfarch-secsh-tyoxbijeg7-archive@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 181411200C1 for <ietfarch-secsh-tyoxbijeg7-archive@ietfa.amsl.com>; Sat, 25 Mar 2017 02:57:25 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.2
X-Spam-Level:
X-Spam-Status: No, score=-4.2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.001, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=auckland.ac.nz
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ABBbhP0ltpHu for <ietfarch-secsh-tyoxbijeg7-archive@ietfa.amsl.com>; Sat, 25 Mar 2017 02:57:23 -0700 (PDT)
Received: from mail.netbsd.org (mail.NetBSD.org [IPv6:2001:470:a085:999::25]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 4D25E124BE8 for <secsh-tyoxbijeg7-archive@lists.ietf.org>; Sat, 25 Mar 2017 02:57:20 -0700 (PDT)
Received: by mail.netbsd.org (Postfix, from userid 605) id 84BC6855F3; Sat, 25 Mar 2017 09:57:19 +0000 (UTC)
Delivered-To: ietf-ssh@netbsd.org
Received: from localhost (localhost [127.0.0.1]) by mail.netbsd.org (Postfix) with ESMTP id ACFC0855EE for <ietf-ssh@netbsd.org>; Sat, 25 Mar 2017 09:57:17 +0000 (UTC)
X-Virus-Scanned: amavisd-new at netbsd.org
Authentication-Results: mail.netbsd.org (amavisd-new); dkim=pass (2048-bit key) header.d=auckland.ac.nz
Received: from mail.netbsd.org ([127.0.0.1]) by localhost (mail.netbsd.org [127.0.0.1]) (amavisd-new, port 10025) with ESMTP id 4P95e6mObcJf for <ietf-ssh@netbsd.org>; Sat, 25 Mar 2017 09:57:17 +0000 (UTC)
Received: from mx4.auckland.ac.nz (mx4.auckland.ac.nz [130.216.125.248]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.netbsd.org (Postfix) with ESMTPS id 9270784CDD for <ietf-ssh@netbsd.org>; Sat, 25 Mar 2017 09:57:15 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=auckland.ac.nz; i=@auckland.ac.nz; q=dns/txt; s=mail; t=1490435836; x=1521971836; h=from:to:subject:date:message-id:references:in-reply-to: content-transfer-encoding:mime-version; bh=/KCvue+CJFQyARsaog7kx5artQlh5EBKKkbI3RDX0j8=; b=5m2/T4JJI++q4OCsQsEj1A5dkmdm+WwOPLw0vwQicyHmYxkcNYmfNVBr r+3PC9BFVf4V9Iks80uUouU19n134ZVy2T5IY/wrSKt0B8IBHCpnfsrg8 2DwEpaHUFCsQkVW3fCpDwpYMN1oWci7/Mh89LhrF1pDUlmz9KyYqPnekL rDRv/VuUQAefyXu5KCD9wG0QouEtjnyCOPBymsbc5/Rv6u6Qc/N1pTqj7 BnOOIppCKZWoveHvLUqaGxVYWdsWmoiwF6cMiJY5bquJINcC/0G1IErc5 YafJiKjkKd0Ogj8qjRzsWYXqNDUPVmN4ZiqDPR+XWjso/QlizpmYPyyPJ g==;
X-IronPort-AV: E=Sophos;i="5.36,219,1486378800"; d="scan'208";a="145349417"
X-Ironport-HAT: MAIL-SERVERS - $RELAYED
X-Ironport-Source: 10.6.2.3 - Outgoing - Outgoing
Received: from exchangemx.uoa.auckland.ac.nz (HELO uxcn13-ogg-b.UoA.auckland.ac.nz) ([10.6.2.3]) by mx4-int.auckland.ac.nz with ESMTP/TLS/AES256-SHA; 25 Mar 2017 22:56:40 +1300
Received: from uxcn13-ogg-d.UoA.auckland.ac.nz (10.6.2.5) by uxcn13-ogg-b.UoA.auckland.ac.nz (10.6.2.23) with Microsoft SMTP Server (TLS) id 15.0.1263.5; Sat, 25 Mar 2017 22:56:39 +1300
Received: from uxcn13-ogg-d.UoA.auckland.ac.nz ([10.6.2.25]) by uxcn13-ogg-d.UoA.auckland.ac.nz ([10.6.2.25]) with mapi id 15.00.1263.000; Sat, 25 Mar 2017 22:56:39 +1300
From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Mouse <mouse@Rodents-Montreal.ORG>, "ietf-ssh@NetBSD.org" <ietf-ssh@NetBSD.org>
Subject: Re: Fixing exchange of host keys in the SSH key exchange
Thread-Topic: Fixing exchange of host keys in the SSH key exchange
Thread-Index: AQHSo6JCh/pnJs1+UUq8ewlt+ue/5qGhf50AgAIjC1L//16gAIACU2cG
Date: Sat, 25 Mar 2017 09:56:38 +0000
Message-ID: <1490435787911.30810@cs.auckland.ac.nz>
References: <2216143EDEE342A3A5C9BB786F7FEF7A@Khan>, <201703231224.IAA22091@Stone.Rodents-Montreal.ORG> <1490342550681.12528@cs.auckland.ac.nz>, <201703241124.HAA19888@Stone.Rodents-Montreal.ORG>
In-Reply-To: <201703241124.HAA19888@Stone.Rodents-Montreal.ORG>
Accept-Language: en-NZ, en-GB, en-US
Content-Language: en-NZ
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [130.216.158.4]
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Sender: ietf-ssh-owner@NetBSD.org
List-Id: ietf-ssh.NetBSD.org
Precedence: list

Mouse <mouse@Rodents-Montreal.ORG> writes:

>Well, it seems to me that it could be used if the other end first indicates
>support for whatever the use is.  There won't be many such, since either that
>has to be done in the clear or it has to not apply to the first kex, but this
>could be an example: the client indicates its support before the server has
>to generate its KEXINIT packet.

Hmm, so you need to signal that you want to use the RFU field to signal that
you want to do something else?

https://www.youtube.com/watch?v=AW2xyXl2tTI

Prepare to use the RFU field!

Peter.

v2.23.0 | Report a Bug | By Email