Re: [tram] Eric Rescorla's Discuss on draft-ietf-tram-stunbis-16: (with DISCUSS and COMMENT)
Gonzalo Camarillo <gonzalo.camarillo@ericsson.com> Mon, 19 November 2018 14:35 UTC
Return-Path: <gonzalo.camarillo@ericsson.com>
X-Original-To: tram@ietfa.amsl.com
Delivered-To: tram@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C5152130DD5 for <tram@ietfa.amsl.com>; Mon, 19 Nov 2018 06:35:40 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.771
X-Spam-Level:
X-Spam-Status: No, score=-4.771 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.47, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=ericsson.com header.b=Pi2h0TIG; dkim=pass (1024-bit key) header.d=ericsson.com header.b=CEQnCftS
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 WIfpabnd88n6 for <tram@ietfa.amsl.com>; Mon, 19 Nov 2018 06:35:36 -0800 (PST)
Received: from sesbmg22.ericsson.net (sesbmg22.ericsson.net [193.180.251.48]) (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 3C8E112426A for <tram@ietf.org>; Mon, 19 Nov 2018 06:35:36 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; d=ericsson.com; s=mailgw201801; c=relaxed/simple; q=dns/txt; i=@ericsson.com; t=1542638126; x=1545230126; h=From:Sender:Reply-To:Subject:Date:Message-ID:To:CC:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=SKORms3Tbuem02S6hZKdpz6L1jkPSqKxYSaSUf41OIM=; b=Pi2h0TIG3NGjXuFHH8AJ+8v4QxTfltjXmM3Y9GAhjMInLu18UW9AeVrvk/E9p9G5 3bmiJKqJZbvbOzZpnJZ1hH0aBfpVFDt/R97RLheAU/NwEqjHvBZShrWl8M/yaDnz rmyjhBV2AQ2X4DIOfwR48JkRryxZtXLp/gYbYQ1Bxi8=;
X-AuditID: c1b4fb30-f15ff700000043c4-3f-5bf2ca2b5c90
Received: from ESESBMB504.ericsson.se (Unknown_Domain [153.88.183.117]) by sesbmg22.ericsson.net (Symantec Mail Security) with SMTP id 84.22.17348.B2AC2FB5; Mon, 19 Nov 2018 15:35:23 +0100 (CET)
Received: from ESESSMB502.ericsson.se (153.88.183.163) by ESESBMB504.ericsson.se (153.88.183.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3; Mon, 19 Nov 2018 15:35:23 +0100
Received: from EUR03-DB5-obe.outbound.protection.outlook.com (153.88.183.157) by ESESSMB502.ericsson.se (153.88.183.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3 via Frontend Transport; Mon, 19 Nov 2018 15:35:23 +0100
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ericsson.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=SKORms3Tbuem02S6hZKdpz6L1jkPSqKxYSaSUf41OIM=; b=CEQnCftSQkrsWQPXWbzh4JN5ysMgkxmV6Dx1y8vLF65pAFsfZXfKPyZAcPafnbYYdGSDhPB2ZQtNpTceiS7p+kuTj9T5c8B6R1x9iKWFe/G0YvEBIR08KX0BRG9+G88MSn1iedtpcT/D3GEI+64+G/s6okGGR1c/ruvYvdb3qKQ=
Received: from DB7PR07MB4934.eurprd07.prod.outlook.com (20.177.192.211) by DB7PR07MB4523.eurprd07.prod.outlook.com (52.135.140.157) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1361.9; Mon, 19 Nov 2018 14:35:18 +0000
Received: from DB7PR07MB4934.eurprd07.prod.outlook.com ([fe80::b1b5:857b:a4fb:d45d]) by DB7PR07MB4934.eurprd07.prod.outlook.com ([fe80::b1b5:857b:a4fb:d45d%3]) with mapi id 15.20.1361.013; Mon, 19 Nov 2018 14:35:18 +0000
From: Gonzalo Camarillo <gonzalo.camarillo@ericsson.com>
To: Spencer Dawkins at IETF <spencerdawkins.ietf@gmail.com>, Marc Petit-Huguenin <petithug@acm.org>
CC: Eric Rescorla <ekr@rtfm.com>, "tram-chairs@ietf.org" <tram-chairs@ietf.org>, "tram@ietf.org" <tram@ietf.org>, "Asveren, Tolga" <tasveren@rbbn.com>, IESG <iesg@ietf.org>, "draft-ietf-tram-stunbis@ietf.org" <draft-ietf-tram-stunbis@ietf.org>
Thread-Topic: [tram] Eric Rescorla's Discuss on draft-ietf-tram-stunbis-16: (with DISCUSS and COMMENT)
Thread-Index: AQHUgBUYh3SWjavZEkyxlhSdCV9H9w==
Date: Mon, 19 Nov 2018 14:35:18 +0000
Message-ID: <af0635b1-e731-0198-3b71-e3267bc10d0e@ericsson.com>
References: <152390863222.19652.10310304989315386136.idtracker@ietfa.amsl.com> <c0a06754-6f8c-97dc-7f7e-26a7df43e842@acm.org> <CABcZeBNk4KWA1Bzw7=i=Siie_6Vf7v-v2cfDyA4WvSAE2D9hrA@mail.gmail.com> <02569943-db8f-654e-7322-49bc1f1a1163@acm.org> <CABcZeBN2=a90qbgo8MkihVFpO2bBzi2Ceepj3UpXVxAZJKJrxg@mail.gmail.com> <235b838f-2800-2cd0-8b01-947e70837619@ericsson.com> <CABcZeBMn1G8BT13bx3JTs04zwQk8K72+btj=xwC662F5AcANXg@mail.gmail.com> <cbb48225-5089-9275-787c-38fa4504a6a4@acm.org> <CABcZeBPNwu-tr8Tf_DiW2iOVy2NDEJoLwAR-6=EWHZak2gVMYg@mail.gmail.com> <c135ad63-bb18-a5f2-4aa2-e2a3268ac26f@acm.org> <CAKKJt-e1XFJNrx-LKmpZFDy6ZuaXt5+Lp+Uw90-Bu-M22PMt3Q@mail.gmail.com> <472563ee-5fc3-655d-8e31-138cc774e608@acm.org> <CAKKJt-dXijVNnAtYojq9x=9_m0pwAM8XTNP8wUEMvAa+m9UXUA@mail.gmail.com>
In-Reply-To: <CAKKJt-dXijVNnAtYojq9x=9_m0pwAM8XTNP8wUEMvAa+m9UXUA@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [89.166.49.243]
user-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
x-clientproxiedby: AM6PR0202CA0068.eurprd02.prod.outlook.com (2603:10a6:20b:3a::45) To DB7PR07MB4934.eurprd07.prod.outlook.com (2603:10a6:10:5b::19)
authentication-results: spf=none (sender IP is ) smtp.mailfrom=gonzalo.camarillo@ericsson.com;
x-ms-exchange-messagesentrepresentingtype: 1
x-ms-publictraffictype: Email
x-microsoft-exchange-diagnostics: 1; DB7PR07MB4523; 6:vm1mgRzYa8ELWtBeUCz3mwJdA/XtHLowFlmxK6etfBVQkJwj+BuLQUdt6djx7oFsqyHQfQFcJ9fe6yQiqr4/isEv2x0kw9BS6hN2at6nXuffQja3J4+Wt7lx7PSw+uLLUeyfLLvdlPJY+5w8XThg9mW0q4+XCb0yPEGEeydC7OylqMxAcHSfuaTC1eOrdq1ZFP/rkh13NUkpE91BmMyErb8fWeEzJEL/zSShQoLrFCg0oFPK378jLeJgCtgA2Nwhq1VJjSRvkU+FE6ubQE1Ou09PvWpIsCedytk0IgTO56kMvrmdwOzTu7h+6IGdlXXZrEW4LpqRj1xFR3YGUogUKnneVsF2CAX6DQ0mUzfF64hwPLkQdoxPgS1QwJ2BVGPRyNJUBdufQmaW8jHtOis3BOCgVaw3+6Hqg6GU+J/9D9kQ+2wfJGvBBVbtIvI0ehlih408Zfsu26yEtPoyrkjrEg==; 5:U5vHW/Ikg50xIZJkiGYtjxK2VHa4OCUti1qxWSBHG500RQw/XvDVXsWWEYNin74xHVgDfMbVfl/2MTFTNrdsykVf71ldNBzCAKzWO6XSB+nBpKSrr3236djYD4wovwAhyDsIq6Cv9IAFyPHJFw59ey7Kbd9I6SBTDYene7PkV/c=; 7:zZ3lVipXwPy5EBApvocoLw/e3WK/fk/Q16bLqRZGDX1kf4Hhw6zmgMR60OUqcaP2OEryIRUNf3EjCn3xxRVOqspnZfZ7STHCRbq7RJ503sYe8Rjp8r/c7aWWT/UX7U8frDjDgB0LXAr8Q9JSkVSnaQ==
x-ms-office365-filtering-correlation-id: 27860c1a-8d4d-4f4e-cce9-08d64e2c3a25
x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390098)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600074)(711020)(2017052603328)(7153060)(7193020); SRVR:DB7PR07MB4523;
x-ms-traffictypediagnostic: DB7PR07MB4523:
x-microsoft-antispam-prvs: <DB7PR07MB452393F9B6829E5B6C45522983D80@DB7PR07MB4523.eurprd07.prod.outlook.com>
x-ms-exchange-senderadcheck: 1
x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(8211001083)(6040522)(2401047)(5005006)(8121501046)(3002001)(10201501046)(93006095)(93001095)(3231415)(944501410)(52105112)(148016)(149066)(150057)(6041310)(20161123564045)(20161123562045)(20161123560045)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(201708071742011)(7699051)(76991095); SRVR:DB7PR07MB4523; BCL:0; PCL:0; RULEID:; SRVR:DB7PR07MB4523;
x-forefront-prvs: 08617F610C
x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(366004)(39860400002)(346002)(396003)(376002)(136003)(54094003)(252514010)(51444003)(199004)(189003)(71200400001)(97736004)(64126003)(8676002)(316002)(3260700006)(25786009)(478600001)(81166006)(81156014)(4326008)(6306002)(2906002)(14454004)(446003)(551934003)(106356001)(52116002)(68736007)(5660300001)(36756003)(8936002)(6512007)(71190400001)(256004)(966005)(93886005)(99286004)(53946003)(14444005)(53936002)(4744004)(2616005)(476003)(31696002)(551544002)(486006)(45080400002)(11346002)(86362001)(65806001)(65956001)(66066001)(65826007)(53546011)(386003)(6506007)(31686004)(2900100001)(76176011)(105586002)(6486002)(110136005)(6246003)(58126008)(6436002)(229853002)(305945005)(7736002)(3846002)(54906003)(102836004)(6116002)(39060400002)(186003)(26005)(579004); DIR:OUT; SFP:1101; SCL:1; SRVR:DB7PR07MB4523; H:DB7PR07MB4934.eurprd07.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1;
received-spf: None (protection.outlook.com: ericsson.com does not designate permitted sender hosts)
x-microsoft-antispam-message-info: LN8xAcPdv9avg9zHv1BHOHyFarExQrfjb/W4z9aFHoJnDw5YcbrTV+cm41zWNcQ+XLx5wJi+Lmql3sIAt0Apagx4UNDG0BmyXFDxoZK1Fc/lLyBBkKKg2MD8zq1Yagf16rpnyNRJioDD2x9Dv4pIKIh3VP/nA+cpghrabOPbymPLGMU6vv77EnIgIVGDYiR1CItKvn3SUsV9m4Tpj4y/MWyGNmP0+25MXOD89NW9KtFns2vtn8Fh6a9WMi2CyD31RbhE3AhBB0IK4v1L6sIK91a3q6yhxVrK/09ys9oZrgWlTinkqOS9QOEmDquaWUwciUqAlQDX3ydQ4tBfDh0bp+meGSAxpikF/Lb77CQ28Is=
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: text/plain; charset="utf-8"
Content-ID: <9EDD6BAA0A04F142BACADE8F457CB31D@eurprd07.prod.outlook.com>
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 27860c1a-8d4d-4f4e-cce9-08d64e2c3a25
X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Nov 2018 14:35:18.7942 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 92e84ceb-fbfd-47ab-be52-080c6b87953f
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR07MB4523
X-OriginatorOrg: ericsson.com
X-Brightmail-Tracker: H4sIAAAAAAAAA01Sa0hTYRjmO2dnOxsNvrzkm5Xgoh9K3qUOJFoIMQzF6k9ooitPKuq0MxU1 CDOUvKRmVrosw4bmLWHeRfOSpg7vhpopaU5KLRUDy9Ro2zHo3/O8z/O8l4+PJs3aKGs6QhnH ckpFlEwoERRdaYp3cNRtBjo/d2cy6ieEzKvVYRFTuPuAZEar5wimrKCNZGrLt0RM+XaFkNmo GRWepeUT7y/IW9RzIrlGs03I24rzkfzhYjrpTwVIPELZqIgElnPyDJGEj/3aEMQOZxOJVV8L UAqaTSMyEU0DdgddzolMJKHNcA+Cpd+fCJ5sIehobKUykdhANATsjXBGQYDzSKgo3SB4oYCA 3EZvPvEZQfF2BmlsK8QM3Ks6ZfRY4DBoL2pBRg+JtxFsdRmJmDY3CB9Xpiij3wKHw8SOD+93 hOW1WVMbAT4BhVkmtxR7wf38RhE/6qUQtHrjKDEtxhehbrjEhBE+BD911abdSGwFM/oSEwaM QdM2QvLYEpYX/1A8toWhtQWTxxIHwVLqgul6wIUIqnebRXxTBcyn1eyHT8LQlB7x+BiMl2Qh PjAphD7tjpAXfKFmvk/AC6MI5qZb9sfZQ+6jZ/srRcJSyTiVh9zU/22rNlxNYjuobXXiy3IY G0iheGwLBVkLIrXpNQ7CQJFe8AJRlchSxaquRYe5ujqyXMR1lSpG6ahk47TI8Ke66necm9Hy l3PdCNNIdkCqC9oMNKMUCaqk6G4ENCmzkPqXGUrSUEVSMsvFBHPxUayqGx2hBTIrKeNXF2CG wxRxbCTLxrLcP5WgxdYpyN3+h0fe+GD/jQrzzje3Qxrulk5LsaWLlfit3bsZu/St1p6M79k+ WYkjs0+S3VqCbWq50n6xdN17Nei4xOa0sji4Q3RVd9j3Q87gzM2B9tdnxjrLn96RnN+zGdb2 Wom83NbdVvT6yN2jk5fjv1WXN+XeUl/y9/NMHWmozH3cq3TQygSqcIWLPcmpFH8BI565RE8D AAA=
Archived-At: <https://mailarchive.ietf.org/arch/msg/tram/f7TgGhQjd9ZT8fhepk6s2vDZQhg>
Subject: Re: [tram] Eric Rescorla's Discuss on draft-ietf-tram-stunbis-16: (with DISCUSS and COMMENT)
X-BeenThere: tram@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Discussing the creation of a Turn Revised And Modernized \(TRAM\) WG, which goal is to consolidate the various initiatives to update TURN and STUN." <tram.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tram>, <mailto:tram-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tram/>
List-Post: <mailto:tram@ietf.org>
List-Help: <mailto:tram-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tram>, <mailto:tram-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 19 Nov 2018 14:35:41 -0000
Hi Spencer, what is the status of this? Are the authors and the document shepherd working with the relevant ADs on the discusses? https://datatracker.ietf.org/doc/draft-ietf-tram-stun-pmtud/ballot/ Cheers, Gonzalo On 24-Oct-18 16:40, Spencer Dawkins at IETF wrote: > Hi, Marc, > > On Wed, Oct 24, 2018 at 3:44 AM Marc Petit-Huguenin <petithug@acm.org > <mailto:petithug@acm.org>> wrote: > > Hi Spencer, > > I sent my answers to Eric Rescorla questions on 2018-10-07 following > an in-person meeting with my co-author, but never got a response > back. Because there was no change proposed by Eric I went ahead and > published -19 a couple of weeks after that, with the text agreed in > response to Adam's and Benjamin's comments. > > https://www.ietf.org/mail-archive/web/tram/current/msg02635.html > > > Ah - I wonder if that was what had happened. > > It sounds like you did the right thing, and that Eric has now responded, > which is also the right thing to do. > > Thanks for helping me understand. > > Spencer > > > On 10/23/18 7:28 PM, Spencer Dawkins at IETF wrote: > > Hi, Marc, > > > > I see that a -19 has been submitted, but didn't see a reply from > Eric in > > this thread. Do you think that you've converged? > > > > (I saw an offer of a conference call, so thought an out-of-band > > conversation might have happened) > > > > Thanks, > > > > Spencer > > > > On Sun, Oct 7, 2018 at 9:35 AM Marc Petit-Huguenin > <petithug@acm.org <mailto:petithug@acm.org>> wrote: > > > >> Hi Eric, > >> > >> Please see inline. > >> > >> On 09/10/2018 03:25 AM, Eric Rescorla wrote: > >>> On Sat, Sep 8, 2018 at 2:31 PM, Marc Petit-Huguenin > <petithug@acm.org <mailto:petithug@acm.org>> > >>> wrote: > >>> > >>>> Hi Eric, > >>>> > >>>> Apologies for the delay in getting back to that. > >>>> > >>>> I think that there is some misunderstanding in what STUNbis is > trying to > >>>> do, so please see my comments inline. > >>>> > >>>> On 06/18/2018 10:43 AM, Eric Rescorla wrote: > >>>>> Hi folks, > >>>>> > >>>>> I've reviewed the new version, but I don't think that the biddown > >>>>> discussion makes much sense. > >>>>> > >>>>> To recap, there are two hashes here: > >>>>> > >>>>> - The hash which you use to store the password with (currently > mostly > >>>> MD5) > >>>>> - The hash you use to compute the MAC (currently SHA-1). > >>>>> > >>>>> First, let's stipulate that MD5 isn't a great choice here, > though SHA-1 > >>>>> isn't a great choice > >>>>> either for pwd hashing You want Argon or the like. With that said, > >>>> there's > >>>>> no sensible > >>>>> biddown attack on that hash because it's a per-server feature, > not a > >>>>> per-transaction > >>>>> feature. So, as long as the server has MD5-hashed passwords, the > >>>> situation > >>>>> is bad. > >>>> > >>>> In no place in STUNbis we are proposing to use SHA-1 for password > >>>> encryption, so I am not sure where that come from. What we > propose is: > >>>> > >>> > >>> You're right, it's SHA-256, but my criticisms apply equally there. > >> > >> SHA-256 was what the WG adopted. Our attempts to add other passwords > >> encryption mechanisms were denied. It is true that Argon2 was > not in that > >> list (in our defense Argon2 was not known before July 2015), but > I do not > >> see why the WG would have accepted that one over the others. > Anyway it is > >> too late to fix this, as it is my understanding that the WG does > not have > >> enough energy to reach consensus on a new password algorithm. > Someone can > >> just write a draft adding Argon2 as password encryption, as we > will have a > >> IANA registry for that. > >> > >>> > >>> > >>>> - Establish a registry for new password algorithms (section > 18.5), so > >>>> algorithms like Argon2 could be added later (but note that our own > >>>> proposals to add more password algorithms were rejected by the > working > >>>> group). > >>>> - Add a new password algorithm to that registry, namely SHA-256. > >>>> - Register MD5 as an initial password algorithm for backward > >> compatibility > >>>> purpose. > >>>> > >>>> As for the biddown protection itself, it is my recollection that it > >>>> happened more or less like that: > >>>> > >>>> > >>>> INT. MEETING ROOM - DAY > >>>> > >>>> One of the co-editors of STUNBis stands at the microphone: > >>>> > >>>> CO-EDITOR > >>>> We added SHA-256 protection for passwords > >>>> in STUNBis. > >>>> > >>>> SOMEONE (V.O.) > >>>> As MD5 still need to be supported, you need to add > >>>> protection for bid-down attacks. > >>>> > >>>> CLOSE-UP on CO-EDITOR ROLLING HIS EYES > >>>> > >>>> CO-EDITOR > >>>> OK, I'll work on that. > >>>> > >>>> Four to eight months has passed. > >>>> > >>>> INT. ANOTHER MEETING ROOM - DAY > >>>> > >>>> The same co-editor of STUNBis stands at the microphone: > >>>> > >>>> CO-EDITOR > >>>> We added a nice mechanism to prevent bid-down > >>>> attacks on passwords. Any comments? > >>>> > >>>> THE ROOM > >>>> (silence) > >>>> > >>>> CO-EDITOR > >>>> Moving on... > >>>> > >>> > >>> I don't see how any of this is relevant to my technical points > above. > >> > >> My point was that we, the co-editors, did not decide on adding > bid-down > >> protection, someone asked us to do so and no-one in the WG saw > any problem > >> with that. The reasons that person wanted that are not known to > us but, as > >> you insist, here's one reason I can think of: > >> > >> It is a fact that, for operational reasons, a password database > cannot be > >> re-encrypted at once. Also for operational reasons, the MD5 password > >> cannot be immediately removed from the database as soon the user > submitted > >> a new one. In fact, and for quite some time, both encrypted > variants of > >> the same password may have to be kept in that database, because a > single > >> user may use a mix of devices, some of them that use an RFC 5389 > client, > >> some that use a STUNbis client. It is up to the STUN server owner to > >> decide how long the migration to STUNbis will take and when it > will be > >> acceptable to reject all RFC 5389 (i.e. MD5) clients (that > migration time > >> can be purposely reduced to 0 seconds but that's the choice and > >> responsibility of the owner of the server). > >> > >> Meanwhile we still need to be sure that if the STUN client is > implementing > >> STUNbis it unconditionally gets the additional protection of the new > >> password encryption algorithm. That's where the biddown > protection kicks > >> in, by preventing an online attacker to have the server > misidentifying a > >> STUNbis client as an RFC 5389 client, by preventing an online > attacker to > >> have the client misidentifying a STUNbis server as a RFC 5389 > server, and > >> having both them use the MD5 encrypted password instead of the > SHA-256 > >> encrypted password, all of that easily done by stripping the > unprotected > >> 401 response of the new STUNbis PASSWORD-ALGORITHMS attribute. > >> > >>> > >>> > >>> > >>>>> The second topic is the hash used to compute the MAC. However, > I don't > >>>> see > >>>>> how > >>>>> this gives you sensible biddown protection because that hash > is also > >> used > >>>>> to compute > >>>>> MAC over the negotiation: an attacker who has compromised a > MAC which > >> the > >>>>> server > >>>>> supports will quite likely be able to forge a MAC over the > transcript > >> as > >>>>> well. This is, > >>>>> I suppose, potentially useful as a defense against some other > weakness > >>>>> (e.g., > >>>>> version #), but I don't really see how the current design > helps against > >>>>> attacks on the > >>>>> MAC. > >>>> > >>>> There is no biddown attack protection for the MAC, as stated in > Section > >>>> 16.3: > >>>> > >>>> "The bid-down protection mechanism described in this document > is new, > >>>> and thus cannot currently protect against a bid-down attack that > >>>> lowers the strength of the hash algorithm to HMAC-SHA1." > >>>> > >>>> What we put in place is a plan for *future* versions of STUN to get > >>>> biddown protection for the MAC. That's it, no more, no less. > >>>> > >>> > >>> Yes, but I don't believe that this will provide bid-down > protection for > >> the > >>> MAC in the future for the reasons I indicate above. > >>> > >>> If you think this does something useful, please show me an > example attack > >>> and how this fixes it. Note that it's not generally useful to > just bid > >> down > >>> the MAC itself unless the MAC you bid down to is weak enough to > exploit > >> in > >>> some other way. > >> > >> I do not know what weaknesses will be discovered in the future. > I am also > >> pretty sure that the cost of not using that mechanism is very > close to 0. > >> What I am sure of is that the cost of reengineering a new biddown > >> protection mechanism if we ever need it will be high. We already > went > >> through the pains of designing one for the password algorithm, so > why not > >> extend it so it can be used in the aftermath of the next Snowden > facepalm > >> moment? > >> > >>> Again, happy to have a call to walk though this if that > >>> helps. > >>> > >>> -Ekr > >>> > >>> > >>> > >>> > >>>>> > >>>>> You might think that there was a MAC which was easier to > reverse to > >> find > >>>>> the original > >>>>> password, but the defense you have here doesn't help with that > because > >>>> the > >>>>> on-path attacker can do a bid-down and use the client as a MAC > oracle > >> for > >>>>> any MAC the client supports. > >>>>> > >>>>> So, I still don't understand what this is supposed to do. Happy to > >> have a > >>>>> call if you > >>>>> think that helps > >>>>> > >>>>> -Ekr > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> On Mon, Jun 18, 2018 at 3:40 AM, Gonzalo Camarillo < > >>>>> Gonzalo.Camarillo@ericsson.com > <mailto:Gonzalo.Camarillo@ericsson.com>> wrote: > >>>>> > >>>>>> Marc, Eric, > >>>>>> > >>>>>> what is the status of this discussion? > >>>>>> > >>>>>> Thanks, > >>>>>> > >>>>>> Gonzalo > >>>>>> > >>>>>> On 04/05/2018 2:35 AM, Eric Rescorla wrote: > >>>>>>> > >>>>>>> > >>>>>>> On Mon, Apr 23, 2018 at 11:16 AM, Marc Petit-Huguenin < > >>>> petithug@acm.org <mailto:petithug@acm.org> > >>>>>>> <mailto:petithug@acm.org <mailto:petithug@acm.org>>> wrote: > >>>>>>> > >>>>>>> On 04/22/2018 05:22 PM, Eric Rescorla wrote: > >>>>>>> > On Sun, Apr 22, 2018 at 2:02 PM, Marc Petit-Huguenin < > >>>>>> petithug@acm.org <mailto:petithug@acm.org> > <mailto:petithug@acm.org <mailto:petithug@acm.org>>> > >>>>>>> > wrote: > >>>>>>> > > >>>>>>> >> > >>>>>>> >>>> For a request or indication message, the agent > MUST > >>>>>> include the > >>>>>>> >>>> USERNAME, MESSAGE-INTEGRITY-SHA256, and > >> MESSAGE-INTEGRITY > >>>>>>> >> attributes > >>>>>>> >>>> in the message unless the agent knows from an > external > >>>>>> indication > >>>>>>> >>>> which message integrity algorithm is supported > by both > >>>>>> agents. In > >>>>>>> >>>> this case either MESSAGE-INTEGRITY or > >>>>>> MESSAGE-INTEGRITY-SHA256 MUST > >>>>>>> >>>> be included in addition to USERNAME. The HMAC > for the > >>>>>> MESSAGE- > >>>>>>> >>> > >>>>>>> >>> This text appears to conflict with S 7.3 of > 5245-bis, which > >>>> says: > >>>>>>> >> > >>>>>>> >> [text missing] > >>>>>>> >> > >>>>>>> >> Hmm, no, RFC245bis is still referencing RFC5389, so the > >>>> procedure > >>>>>> for > >>>>>>> >> stunbis does not apply. > >>>>>>> >> > >>>>>>> > > >>>>>>> > I hear what you're saying, but publishing two > documents at the > >>>>>> same time > >>>>>>> > which > >>>>>>> > make contrary recommendations about the same basic > protocol is > >>>>>> un-good. > >>>>>>> > >>>>>>> Sure, but wouldn't it be simpler to have rfc5245bis > using stunbis > >>>>>>> and have them updating their text, more than adding some > tortuous > >>>>>>> text in stunbis? > >>>>>>> > >>>>>>> > > >>>>>>> > > >>>>>>> >>> The STUN usage must specify which transport > protocol is > >>>>>> used, and > >>>>>>> >> how > >>>>>>> >>>> the agent determines the IP address and port > of the > >>>>>> recipient. > >>>>>>> >>>> Section 8 describes a DNS-based method of > determining > >> the > >>>>>> IP > >>>>>>> >> address > >>>>>>> >>>> and port of a server that a usage may elect to > use. > >> STUN > >>>>>> may be > >>>>>>> >> used > >>>>>>> >>>> with anycast addresses, but only with UDP and > in usages > >>>>>> where > >>>>>>> >>>> authentication is not used. > >>>>>>> >>> > >>>>>>> >>> Why this restriction? You should be able to use > anycast with > >>>>>> long-term > >>>>>>> >>> AUTH for (say) TURN. > >>>>>>> >> > >>>>>>> >> https://www.ietf.org/mail-archive/web/behave/current/ > >>>>>> msg03582.html > >>>>>>> <https://www.ietf.org/mail-archive/web/behave/current/ > >>>> msg03582.html> > >>>>>>> >> > >>>>>>> >> I think that the decision of permitting Anycast > should be left > >>>> to > >>>>>> each > >>>>>>> >> STUN Usage. Basic STUN Usage does not use > authentication and > >>>> use > >>>>>> only a > >>>>>>> >> one round trip for the Binding transaction, so > Unicast can be > >>>>>> used. > >>>>>>> >> > >>>>>>> > > >>>>>>> >> OTOH, TURN and ICE should probably say something > about that, > >> so > >>>> I > >>>>>> added a > >>>>>>> >> new bullet point in Section 13: > >>>>>>> >> > >>>>>>> >> o If Anycast addresses can be used for the server > in case > >>>> TCP > >>>>>> or > >>>>>>> >> TLS-over-TCP, or authentication are used. > >>>>>>> >> > >>>>>>> > > >>>>>>> > Are you leaving this text in? That seems very confusing. > >>>>>>> > >>>>>>> In isolation yes, but I think it makes sense which the text > >> before > >>>>>>> the bullet points: > >>>>>>> > >>>>>>> A STUN usage defines how STUN is actually utilized -- > when to > >>>> send > >>>>>>> requests, what to do with the responses, and which > optional > >>>>>>> procedures defined here (or in an extension to STUN) > are to be > >>>>>> used. > >>>>>>> A usage also defines: > >>>>>>> > >>>>>>> [...] > >>>>>>> > >>>>>>> o If Anycast addresses can be used for the server in > case TCP > >>>> or > >>>>>>> TLS-over-TCP, or authentication are used. > >>>>>>> > >>>>>>> > >>>>>>> What is the need for the restriction at all. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> >>>> transaction over UDP or DTLS-over-UDP is also > >> considered > >>>>>> failed if > >>>>>>> >>>> there has been a hard ICMP error [RFC1122]. For > >> example, > >>>>>> assuming > >>>>>>> >> an > >>>>>>> >>>> RTO of 500ms, requests would be sent at times > 0 ms, 500 > >>>>>> ms, 1500 > >>>>>>> >> ms, > >>>>>>> >>>> 3500 ms, 7500 ms, 15500 ms, and 31500 ms. If the > >> client > >>>>>> has not > >>>>>>> >>>> received a response after 39500 ms, the client > will > >>>>>> consider the > >>>>>>> >>>> transaction to have timed out. > >>>>>>> >>> > >>>>>>> >>> I note that these recommendations now seem crazily > long. I > >>>>>> assume the > >>>>>>> >>> WG had consensus on this, but I wanted to note it. > >>>>>>> >> > >>>>>>> >> Not just the WG, also the IESG that approved RFC 5389 > too as, > >>>> but > >>>>>> for the > >>>>>>> >> addition of "or DTLS-over-UDP", this is the same text > than in > >>>> RFC > >>>>>> 5389. > >>>>>>> >> > >>>>>>> > > >>>>>>> > Yes, I know. My point is that while they might have bee > >> sensible > >>>>>> when > >>>>>>> > 5389 was published they *now* seem crazily long. Did > the WG > >>>>>> explicitly > >>>>>>> > decide not to update them? > >>>>>>> > >>>>>>> No, nobody ever suggested that there was an issue there. > >>>>>>> > >>>>>>> > >>>>>>> OK, well, this seems like it should be considered, then, > because this > >>>>>>> doesn't > >>>>>>> match modern practice. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > This would be good to explain. > >>>>>>> > >>>>>>> New text: > >>>>>>> > >>>>>>> [...] > >>>>>>> containing the subjectAltName of that certificate. > The test > >> on > >>>>>> the > >>>>>>> MESSAGE-INTEGRITY-SHA256 attribute indicates that the > >>>> transaction > >>>>>> is > >>>>>>> authenticated and that the client implements this > >> specification > >>>>>> and > >>>>>>> so can process the ALTERNATE-DOMAIN attribute. > >>>>>>> > >>>>>>> > >>>>>>> All right. > >>>>>>> > >>>>>>> > >>>>>>> > > >>>>>>> > > >>>>>>> >>>> o What authentication and message-integrity > mechanisms > >>>>>> are used. > >>>>>>> >>>> > >>>>>>> >>>> o The considerations around manual vs. > automatic key > >>>>>> derivation > >>>>>>> >> for > >>>>>>> >>>> the integrity mechanism, as discussed in > [RFC4107]. > >>>>>>> >>>> > >>>>>>> >>>> o What mechanisms are used to distinguish STUN > >> messages > >>>>>> from other > >>>>>>> >>> > >>>>>>> >>> Why is this required? It seems like that's a generic > STUN > >>>>>> feature. > >>>>>>> >> > >>>>>>> >> That text is identical to the text in RFC 5389. RFC > 5764/7983 > >>>> is > >>>>>> one such > >>>>>>> >> mechanism, but there is nothing that prevent another > protocol > >>>>>> stack to use > >>>>>>> >> a different mechanism (inference, shim, etc...) > >>>>>>> >> > >>>>>>> > > >>>>>>> > But ultimately no matter what the other protocol > provides for > >>>>>> demux, STUN > >>>>>>> > has its > >>>>>>> > own demux. > >>>>>>> > >>>>>>> In fact I think that the reason for that item was because > >>>>>>> FINGERPRINT can also be used to demux STUN traffic, but > it is > >>>>>>> optional. So an STUN Usage needs to tell if FINGERPRINT is > >>>>>>> mandatory (like in ICE). > >>>>>>> > >>>>>>> > >>>>>>> This should be explained. > >>>>>>> > >>>>>>> > >>>>>>> >>> > >>>>>>> >>>> that is not readily subject to offline dictionary > >>>> attacks. > >>>>>>> >>>> Protection of the channel itself, using TLS or > DTLS, > >>>>>> mitigates > >>>>>>> >> these > >>>>>>> >>>> attacks. > >>>>>>> >>>> > >>>>>>> >>>> STUN supports both MESSAGE-INTEGRITY and > >>>>>>> MESSAGE-INTEGRITY-SHA256, > >>>>>>> >>>> which is subject to bid down attacks by an on-path > >>>>>> attacker. > >>>>>>> >>> > >>>>>>> >>> By an on-path attacker who can forge HMAC-SHA1 in > real-time? > >>>>>>> That's a > >>>>>>> >>> pretty serious adversary, so you should clarify here > >>>>>>> >>> > >>>>>>> >> > >>>>>>> >> New text: > >>>>>>> >> > >>>>>>> >> STUN supports both MESSAGE-INTEGRITY and > >>>>>> MESSAGE-INTEGRITY-SHA256, > >>>>>>> >> which is subject to bid down attacks by an on-path > attacker > >>>>>> that > >>>>>>> >> would strip the MESSAGE-INTEGRITY-SHA256 attribute > leaving > >>>>>>> only the > >>>>>>> >> MESSAGE-INTEGRITY attribute and exploiting a potential > >>>>>>> vulnerability. > >>>>>>> >> Protection of the channel itself, using TLS or DTLS, > >>>> mitigates > >>>>>>> these > >>>>>>> >> attacks. Timely removal of the support of > >> MESSAGE-INTEGRITY > >>>>>> in a > >>>>>>> >> future version of STUN is necessary. > >>>>>>> >> > >>>>>>> > > >>>>>>> > I still don't understand the capabilities you seem to > believe > >> the > >>>>>>> attacker > >>>>>>> > has. > >>>>>>> > Can you describe the exact attack. > >>>>>>> > > >>>>>>> > >>>>>>> 1. Vulnerability is found in HMAC-SHA1 > >>>>>>> 2. Client Alice still supports M-I and M-I-256, does not > know > >> what > >>>>>>> version of STUN server Bob supports and so send both. > >>>>>>> 3. On-path attacker removes M-I-256. > >>>>>>> 5. stunbis server Bob thinks that Alice is an RFC 5389 > client and > >>>>>>> continue with that protocol. > >>>>>>> > >>>>>>> > >>>>>>> This seems like an extremely weak attack. In general, any > protocol of > >>>>>>> this type is as strong > >>>>>>> as the weakest integrity algorithm it supports, so it's not > that the > >>>>>>> protocol has a downgrade > >>>>>>> attack, but rather that the minimum algorithm supported is > one you > >>>> don't > >>>>>>> trust as much > >>>>>>> as you might like. > >>>>>>> > >>>>>>> -Ekr > >>>>>>> > >>>>>>> > >>>>>>> -- > >> > > > > -- > Marc Petit-Huguenin > Email: marc@petit-huguenin.org <mailto:marc@petit-huguenin.org> > Blog: https://marc.petit-huguenin.org > Profile: https://www.linkedin.com/in/petithug >
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- [tram] Eric Rescorla's Discuss on draft-ietf-tram… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Brandon Williams
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Matthew A. Miller
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Brandon Williams
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Spencer Dawkins at IETF
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Marc Petit-Huguenin
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Spencer Dawkins at IETF
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Spencer Dawkins at IETF
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Camarillo
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Spencer Dawkins at IETF
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Eric Rescorla's Discuss on draft-ietf-… Eric Rescorla
- [tram] Blackout posting of draft-ietf-tram-stunbi… Spencer Dawkins at IETF
- Re: [tram] Blackout posting of draft-ietf-tram-st… Gonzalo Salgueiro (gsalguei)