From nobody Thu Dec 5 11:11:24 2019 Return-Path: X-Original-To: mls@ietfa.amsl.com Delivered-To: mls@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id B30E8120145 for ; Thu, 5 Dec 2019 11:11:22 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2 X-Spam-Level: X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=cloudflare.com 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 9xcn1BDxvRd2 for ; Thu, 5 Dec 2019 11:11:20 -0800 (PST) Received: from mail-vs1-xe29.google.com (mail-vs1-xe29.google.com [IPv6:2607:f8b0:4864:20::e29]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5D347120168 for ; Thu, 5 Dec 2019 11:11:19 -0800 (PST) Received: by mail-vs1-xe29.google.com with SMTP id x123so3226402vsc.2 for ; Thu, 05 Dec 2019 11:11:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:from:date:message-id:subject:to; bh=AWyPYoLdtek4UtMkOB1aM6FTnHDn03JKv51cYoveC6M=; b=NWN2la3AVzWNycq+BF0jdLROiCwgTf12Hx/CERePE0nu0HIln0ae3tiNW+KKn3sh8H M4UD2D2CPRqa6VLpvtIuZfB/XDM7eqCKPz5lEQYarktJCoPENCr+BqnNl9h9S0ecO+Ba k28nYkRh56RQggMJqjUtpbQB3a9bDIsNaxhQU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=AWyPYoLdtek4UtMkOB1aM6FTnHDn03JKv51cYoveC6M=; b=hNZj9Gy2cqZ/LulSQed9rnSSr0+IesTJZWq5i9OXOwyDezwG645+CRD38Osq8UKluP /Es1g6/82szwOneQIDHsmYYqJxkhbWHpHumCphOFV0splbckDkEPe9erVkKf2+Ti3kDC S0L4JfllEVYS9R4MVZGIwiswHFrGMJrQ/AqdxlvaHTzNT2GEJIXxAFNK7tWzBHlugfxS Zpu8v0MdUZsQ5Z544L8XW08IzIUMwUrodWaqvb4bVS8KIUE+fdlMHi2Hxsr9jl8jz0qI wMskSDW55ZmiY5kOhbIkdh7UkgZSirUKn7/m6XCc0vYrd1/wYY7oOZo+ARla46OSRaaK X2Iw== X-Gm-Message-State: APjAAAUq5iFWsPlfd23E/AfZWPy5wwpqpIR+Sgv27JlS63whMRIIubuh CM5mhnzM3XAbujAXpOrCY0mRCTUYvD0HnOutvX3Rw0p+J+8= X-Google-Smtp-Source: APXvYqz9lkqTW4KX5kGR5thNNy0iDrifssG3NMPVnTZquhtRg83i/JQ8dfqrcDkj7X/Pa+e78uPl0R8CLCcs5gKLui8= X-Received: by 2002:a67:d88b:: with SMTP id f11mr6922265vsj.212.1575573077887; Thu, 05 Dec 2019 11:11:17 -0800 (PST) MIME-Version: 1.0 From: Nick Sullivan Date: Thu, 5 Dec 2019 11:10:37 -0800 Message-ID: To: Messaging Layer Security WG Content-Type: multipart/alternative; boundary="000000000000a0575d0598f9b191" Archived-At: Subject: [MLS] MLS Interim X-BeenThere: mls@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Messaging Layer Security List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Dec 2019 19:11:23 -0000 --000000000000a0575d0598f9b191 Content-Type: text/plain; charset="UTF-8" MLSWG, After the poll we set a date and time for the January 2020 MLS interim. It will be in New York City on January 11-12. This immediately follows the Real World Cryptography conference. We are working on confirming the location for event, and NYU in Lower Manhattan is a strong possibility. Nick & Sean --000000000000a0575d0598f9b191 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
MLSWG,

After the poll we set a date and= time for the January 2020 MLS interim. It will be in New York City on Janu= ary 11-12. This immediately follows the Real World Cryptography conference.=

We are working on confirming the location for eve= nt, and NYU in Lower Manhattan is a strong possibility.

Nick & Sean
--000000000000a0575d0598f9b191-- From nobody Thu Dec 12 10:50:13 2019 Return-Path: X-Original-To: mls@ietfa.amsl.com Delivered-To: mls@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C2E2D1200C3 for ; Thu, 12 Dec 2019 10:50:11 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.999 X-Spam-Level: X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=sn3rd.com 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 BqyfnReJf8rD for ; Thu, 12 Dec 2019 10:50:10 -0800 (PST) Received: from mail-qv1-xf31.google.com (mail-qv1-xf31.google.com [IPv6:2607:f8b0:4864:20::f31]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 366321200B9 for ; Thu, 12 Dec 2019 10:50:10 -0800 (PST) Received: by mail-qv1-xf31.google.com with SMTP id n8so1355664qvg.11 for ; Thu, 12 Dec 2019 10:50:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sn3rd.com; s=google; h=from:content-transfer-encoding:mime-version:subject:message-id:date :to; bh=LTad8vp9u42ezwGsLkMT5vqmTYU/whkaeiunlFWMtc8=; b=ALeb3Q8wyjvAmHc3hLjb0bpsDIjFRNaAGYNUQm1mWa1POiZcdzkLy4RocY8GENv99x nYp+37KPzr/feaVfmjgdpTooYsgtda2ub4LHEc/G8aO2A4UfxnvNPwPOOqaggAnbEnm2 OeiXGzFeGUwOTe46eX+ekaGv/YDC08qvlEYzM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:content-transfer-encoding:mime-version :subject:message-id:date:to; bh=LTad8vp9u42ezwGsLkMT5vqmTYU/whkaeiunlFWMtc8=; b=mG5aONT+ylKXvPF0Lo1RgzVr5T3QZafYkikAk4GzQ52pm6ygkMQixolvi5XjBORs9P Zr9VmLDtJ9UCLvWtUj7MXC6Mr9ioMisi7KR/AzL1naNDxfOVIampO0gZcysH5E6M/MS3 QidzyYd4tpFAGoz2Q25VS82sLER8SpHrVSK2ksyvCZsEivVjWN/UF4NgamKogle7dRf4 yCxk2FXldV68K26VCxVZ3//kRtttUmAXa/waD7wNAOA93ms9kSgUr7Wuq5ToR1NKIbfs Ept2hBawnfpDqp1qdQWAyPG560T1AKtY2cNx/GngG+5zdPYt8+oUiG4gIHTSuzNe2qIA 95qA== X-Gm-Message-State: APjAAAUl9HhWP7BkmICZK91tlGay5h3RsW3dNHcq8pDs9XmJpk8YnHgW +Yqkkw1bPiadSnG14mD84RBMwPmjDoQ= X-Google-Smtp-Source: APXvYqwPfPjwtrskkEfKxEuFJkKDbJfnvB7HpqML3ytEaBdj64V3JMvM050GurtVtBOqfVhHE2FcHQ== X-Received: by 2002:a0c:da08:: with SMTP id x8mr9747646qvj.166.1576176609013; Thu, 12 Dec 2019 10:50:09 -0800 (PST) Received: from sn3rd.lan ([75.102.131.36]) by smtp.gmail.com with ESMTPSA id h34sm2432010qtc.62.2019.12.12.10.50.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Dec 2019 10:50:08 -0800 (PST) From: Sean Turner Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Message-Id: <0BC41077-FF1F-4C88-A5C9-93688EDF8E19@sn3rd.com> Date: Thu, 12 Dec 2019 13:50:07 -0500 To: mls@ietf.org X-Mailer: Apple Mail (2.3445.104.11) Archived-At: Subject: [MLS] January 2020 Interim Registration and Issue discussion X-BeenThere: mls@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Messaging Layer Security List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Dec 2019 18:50:12 -0000 The date and location are set for the January 2020 Interim meeting. It = will be on January 11th and 12th in New York, New York (the specific = location is being worked now). More details can be found on Github: = https://github.com/mlswg/wg-materials/tree/master/interim-2020-01. Please register with the following form if you intend on attending = either remotely or in person. Registration Link (https://forms.gle/ktUTg1V3hJzkyXMv8) Registration deadline closes on December 20th. We are soliciting proposals for presentations to add to the agenda for = the meeting. Please send proposals to mls-chairs@ietf.org. Due to time = limitations, these should be restricted to discussions about current = active drafts. Here are the active documents: Protocol (https://datatracker.ietf.org/doc/draft-ietf-mls-protocol/) Issues: https://github.com/mlswg/mls-protocol/issues Architecture = (https://datatracker.ietf.org/doc/draft-ietf-mls-architecture/) Issues: https://github.com/mlswg/mls-architecture Federation https://datatracker.ietf.org/doc/draft-omara-mls-federation/) Issues: https://github.com/mlswg/mls-federation/issues We encourage the authors and other participants to read these issues, = distill the main questions raised by them and propose answers for = discussion on the list in the coming weeks. Nick and Sean Nick and Sean= From kandriko@student.ethz.ch Thu Dec 12 12:01:34 2019 Return-Path: X-Original-To: mls@ietfa.amsl.com Delivered-To: mls@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id AE3641200D6 for ; Thu, 12 Dec 2019 12:01:34 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.897 X-Spam-Level: X-Spam-Status: No, score=-1.897 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001] autolearn=ham autolearn_force=no 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 taomSPbDYL76 for ; Thu, 12 Dec 2019 12:01:32 -0800 (PST) Received: from mailg110.ethz.ch (mailg110.ethz.ch [IPv6:2001:67c:10ec:5605::21]) (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 6F2FC1200C3 for ; Thu, 12 Dec 2019 12:01:31 -0800 (PST) Received: from mailm212.d.ethz.ch (2001:67c:10ec:5603::26) by mailg110.ethz.ch (2001:67c:10ec:5605::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Thu, 12 Dec 2019 21:01:11 +0100 Received: from mailm214.d.ethz.ch (2001:67c:10ec:5603::28) by mailm212.d.ethz.ch (2001:67c:10ec:5603::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Thu, 12 Dec 2019 21:01:29 +0100 Received: from mailm214.d.ethz.ch ([fe80::18d4:d750:ea54:d4cb]) by mailm214.d.ethz.ch ([fe80::18d4:d750:ea54:d4cb%4]) with mapi id 15.01.1847.005; Thu, 12 Dec 2019 21:01:29 +0100 From: "Andrikopoulos Konstantinos" To: "mls@ietf.org" Thread-Topic: Message Order Thread-Index: AQHVsSI/MT+Se8urBkq/SfU0WidyOQ== Date: Thu, 12 Dec 2019 20:01:29 +0000 Message-ID: <13a195e741e3478b86992d610e1d6fa1@student.ethz.ch> Accept-Language: de-DE, en-GB, en-US, de-CH Content-Language: de-DE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [51.154.73.21] x-tm-snts-smtp: 96614128C4FE68C20788B6BAFB4D82C7289D882EED1BCB0BF4A1444E49FA03232000:8 Content-Type: multipart/alternative; boundary="_000_13a195e741e3478b86992d610e1d6fa1studentethzch_" MIME-Version: 1.0 Archived-At: X-Mailman-Approved-At: Mon, 16 Dec 2019 10:45:24 -0800 Subject: [MLS] Message Order X-BeenThere: mls@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Messaging Layer Security List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Dec 2019 20:07:03 -0000 --_000_13a195e741e3478b86992d610e1d6fa1studentethzch_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello, I am a computer science master's student, focusing on cryptography and secu= rity. As a part of a small research project, supervised by Kenneth Paterson= , I am looking into the MLS protocol. In particular, we have been paying at= tention the message reordering problems that are mentioned in the current d= raft of the protocol. The purpose I am writing this email is that, before we continue further wit= h the project, we would like to see if you have already decided on the dire= ction that you would like the solution to follow. Would you be able to poin= t us to any texts that you may have compiled or past discussions on the sub= ject? Thank you, Konstantinos --_000_13a195e741e3478b86992d610e1d6fa1studentethzch_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hello,


I am a computer science master's student, focusing on cryptography= and security. As a part of a small research project, supervised by Kenneth= Paterson, I am looking into the MLS protocol. In particular, we have been = paying attention the message reordering problems that are mentioned in the current draft of the protocol.


The purpose I am writing this email is that, before we continue fu= rther with the project, we would like to see if you have already decided on= the direction that you would like the solution to follow. Would you be abl= e to point us to any texts that you may have compiled or past discussions on the subject?


Thank you,

Konstantinos

--_000_13a195e741e3478b86992d610e1d6fa1studentethzch_-- From nobody Mon Dec 16 11:32:52 2019 Return-Path: X-Original-To: mls@ietfa.amsl.com Delivered-To: mls@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7C04B1208F2 for ; Mon, 16 Dec 2019 11:32:50 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.897 X-Spam-Level: X-Spam-Status: No, score=-1.897 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=ipv-sx.20150623.gappssmtp.com 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 VGS419SbEeuv for ; Mon, 16 Dec 2019 11:32:48 -0800 (PST) Received: from mail-qv1-xf2e.google.com (mail-qv1-xf2e.google.com [IPv6:2607:f8b0:4864:20::f2e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9D0B71208EB for ; Mon, 16 Dec 2019 11:32:48 -0800 (PST) Received: by mail-qv1-xf2e.google.com with SMTP id dc14so1554457qvb.9 for ; Mon, 16 Dec 2019 11:32:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ipv-sx.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=jGmFK80nlKZPNNl6/Pb4AdUtxCDIjJYDTn7bGoWbaVI=; b=PUuT224LfiTOV4A11Ro4cNm6fEd95T5++lNXwk01UXXjrknNWRX4XzkKGmggcEhTWG mHcisOOQ2GJbDBj9Lxl1eupv3lla90P4GqAmq154+PAdLX035mgv0nDrI/3CxAhpP7DK 082JgC9a8N0jErIYKJwbNU5me7TYA2nWdMUH9glI9fQxs2VGFtdX2f9qdFP3LZD5W7ay ZiZ2Xpo67DDV4rEwZRvqbP5MF6Uj7QxGTvUH4IS4Vi79mKu5w2kTLjc27CkfxrdSU+Qj tQITrfaYXMhozE/vjek6hk+1eBU69BDZHQ5mZXF51D9nPQLynO2TzMz7FS7nU5h5ZOhv 1UiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jGmFK80nlKZPNNl6/Pb4AdUtxCDIjJYDTn7bGoWbaVI=; b=HfNdIt83Ox7xLb1/RiYgcIDrcI2FUmlj23Zvb/y+A39gmdxqi1PPh8ZJKr5IMPRGe4 z34PkBCd5bGjBqMc4Vz2+XvLMTnvtN7BKudO7ZiqopcEFgf9D6IMyg7V+E11H7Cdajk7 Zg3wFoXbtlBxvxsyHmuDFRS9/FnqVt8LnIph0zS6ZaciziEkw8lBjFRbu1fETUhQ2BH3 n2o7DoVbSdonWCZOG3Qa4EMsR12/iLRNhixXkhArSM7QOF4GWbke9quxSZUD8Vz08xvB rOsuKmidkRodpKowxm4RtRABJZ/gEKjYzJPQN1YcV7+jx2Rx62fLbHt+l3XebPoDXkif ItMQ== X-Gm-Message-State: APjAAAVgzqJ8htu9wr9SCxaDVt5I8B/HZKVdkTpa9otr/pLf7HRY9DHG /tTlGO1UOPyZISBizXB4AvHrWeTsTAlyagBMks8sG7M5RSI= X-Google-Smtp-Source: APXvYqyEdofDxs0RQf2JLMu3APzfB1oCEcRbc3uj7YiDNVyKH6aCJ5dypaEJug+XPOKru8Q0/vgn3Yyr6groNwXSHzY= X-Received: by 2002:a0c:f2ce:: with SMTP id c14mr973153qvm.65.1576524767437; Mon, 16 Dec 2019 11:32:47 -0800 (PST) MIME-Version: 1.0 References: <13a195e741e3478b86992d610e1d6fa1@student.ethz.ch> In-Reply-To: <13a195e741e3478b86992d610e1d6fa1@student.ethz.ch> From: Richard Barnes Date: Mon, 16 Dec 2019 14:32:19 -0500 Message-ID: To: Andrikopoulos Konstantinos Cc: "mls@ietf.org" Content-Type: multipart/alternative; boundary="000000000000be39620599d74664" Archived-At: Subject: Re: [MLS] Message Order X-BeenThere: mls@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Messaging Layer Security List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Dec 2019 19:32:50 -0000 --000000000000be39620599d74664 Content-Type: text/plain; charset="UTF-8" Hi Konstantinos, Thanks for reaching out. I think the current thinking is described in the "Sequencing of State Changes" section of the current document [1]. (It probably needs a rewrite, thought, to use more current terminology.) In brief: * The protocol allows each state/epoch to have a single successor [2], * So the members of the group need to agree on which Commit message causes this epoch change. * In some deployment cases, a straightforward way to achieve such agreement is to ensure that all members receive Commits in the same order, so they can just take the first one * You could also envision applying other techniques to agree on which Commit is applied, e.g., running a consensus protocol * These requirements apply only to Commits; Proposals and application messages are uncontentious, and can be arbitrarily reordered in any case The requirement for strict ordering of states is something the group has accepted for a while, since in the primary use case, with a centralized Delivery Service, it seems reasonably achievable. However, it is problematic for more decentralized cases, Matrix [3] being the most-discussed example. To make those scenarios work better, you would need (a) non-linear epoch IDs so that you could tolerate forks in the state history, and (b) a "merge" algorithm so that you could coalesce two forks. Both of those are areas where some additional thinking could be helpful. Hope that helps! --Richard [1] https://github.com/mlswg/mls-protocol/blob/master/draft-ietf-mls-protocol.md#sequencing-of-state-changes-sequencing [2] ... because epochs are identified with a counter, cf. https://github.com/mlswg/mls-protocol/pull/245 [3] https://matrix.org On Mon, Dec 16, 2019 at 1:46 PM Andrikopoulos Konstantinos < kandriko@student.ethz.ch> wrote: > Hello, > > > I am a computer science master's student, focusing on cryptography and > security. As a part of a small research project, supervised by Kenneth > Paterson, I am looking into the MLS protocol. In particular, we have been > paying attention the message reordering problems that are mentioned in the > current draft of the protocol. > > > The purpose I am writing this email is that, before we continue further > with the project, we would like to see if you have already decided on the > direction that you would like the solution to follow. Would you be able to > point us to any texts that you may have compiled or past discussions on the > subject? > > > Thank you, > > Konstantinos > _______________________________________________ > MLS mailing list > MLS@ietf.org > https://www.ietf.org/mailman/listinfo/mls > --000000000000be39620599d74664 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi Konstantinos,

Thanks for = reaching out.=C2=A0 I think the current thinking is described in the "= Sequencing of State Changes" section of the current document [1].=C2= =A0 (It probably needs a rewrite, thought, to use more current terminology.= )=C2=A0 In brief:

* The protocol allows each state= /epoch to have a single successor [2],
* So the members of t= he group need to agree on which Commit message causes this epoch change.
* In some deployment cases, a straightforward way to achieve s= uch agreement is to ensure that all members receive Commits in the same ord= er, so they can just take the first one
* You could also envision= applying other techniques to agree on which Commit is applied, e.g., runni= ng a consensus protocol
* These requirements apply only to Commit= s; Proposals and application messages are uncontentious, and can be arbitra= rily reordered in any case

The requirement for= strict ordering of states is something the group has accepted for a while,= since in the primary use case, with a centralized Delivery Service, it see= ms reasonably achievable.=C2=A0 However, it is problematic for more decentr= alized cases, Matrix [3] being the most-discussed example.=C2=A0 To make th= ose scenarios work better, you would need (a) non-linear epoch IDs so that = you could tolerate forks in the state history, and (b) a "merge" = algorithm so that you could coalesce two forks.=C2=A0 Both of those are are= as where some additional thinking could be helpful.

Hope that helps!
--Richard

[2] ... because epochs are identified wit= h a counter, cf. https://github.com/mlswg/mls-protocol/pull/245

On Mon, Dec 16, 201= 9 at 1:46 PM Andrikopoulos Konstantinos <kandriko@student.ethz.ch> wrote:

Hello,


I am a computer science master's student, focusing on cryptogr= aphy and security. As a part of a small research project, supervised by Ken= neth Paterson, I am looking into the MLS protocol. In particular, we have b= een paying attention the message reordering problems that are mentioned in the current draft of the protocol.


The purpose I am writing this email is that, before we continue fu= rther with the project, we would like to see if you have already decided on= the direction that you would like the solution to follow. Would you be abl= e to point us to any texts that you may have compiled or past discussions on the subject?


Thank you,

Konstantinos

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--000000000000be39620599d74664-- From nobody Thu Dec 19 10:00:04 2019 Return-Path: X-Original-To: mls@ietfa.amsl.com Delivered-To: mls@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2C0D8120902 for ; Thu, 19 Dec 2019 10:00:02 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.999 X-Spam-Level: X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=sn3rd.com 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 zGxpQG3s4gaz for ; Thu, 19 Dec 2019 10:00:00 -0800 (PST) Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 621061208FC for ; Thu, 19 Dec 2019 10:00:00 -0800 (PST) Received: by mail-qk1-x732.google.com with SMTP id z76so5736949qka.2 for ; Thu, 19 Dec 2019 10:00:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sn3rd.com; s=google; h=from:content-transfer-encoding:mime-version:subject:date:references :to:in-reply-to:message-id; bh=NiFpeKGMQPefmsAYeFGHsLcYDAjotyqt4T4B4/Fyk5s=; b=ONMguHZFfv/gwTq4pYXE4IWNtHR1H4tySVc9mhOTOX841+J6gTDqzLsnoDNecMrkeb 13Yu0M2Guz0w40XRq2zECFN/IwBmWdlz1IXl7mL0aRF85HQh4BzPi2YP0B4YJFNrxrdQ vsVommAMczV/r8Yw+2Zu+ACAvQOYFgA/QMDD0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:content-transfer-encoding:mime-version :subject:date:references:to:in-reply-to:message-id; bh=NiFpeKGMQPefmsAYeFGHsLcYDAjotyqt4T4B4/Fyk5s=; b=VmQXhmwZ6BP8uO6+HVnpqowwUDfL3peLpzKti2UHHuTE9INYXHgwGNKQxrU90ct1dK NYjaZxFADjiTJQd6n1KC0W0Nar42wJTSbjNzxwVKGA4Qf6JM9/e8XqjurXHYbwriMQcp UuMKIQQDup73eocSohmULCanTfdX27qNYn3JCx5Y4GoXkcunqb10i9geBXRLFo5Xs5rg be790tnKtv0ShM2hKkRu3ArbC3b29kJTkbf2bVrIPgFbiHMA3BvNCNzAe1wOu2OPIfsS Lqbq1kP8DhZlypV+3OeQu0WpGsQbdeaFzgakqe8dvjYRuKUfvVa3rHubsUqrretOcBG6 kxBQ== X-Gm-Message-State: APjAAAX7nprtvaaMpPrc2taP19j/8uHnmhjEDlautbIksDHxhloj9yUZ x/9UxQ5zaf9BZq0wgmbCFY2w15/JXWI= X-Google-Smtp-Source: APXvYqyZiCt/MXG1Xu94hJlK81D9Z8Z5y85iS6TjSgu9MKzsJ8xXyZdWyiFNuy8uNnRt1DorlYWq9Q== X-Received: by 2002:a05:620a:201d:: with SMTP id c29mr1297197qka.91.1576778399237; Thu, 19 Dec 2019 09:59:59 -0800 (PST) Received: from sn3rd.lan ([75.102.131.36]) by smtp.gmail.com with ESMTPSA id z4sm1898462qkz.62.2019.12.19.09.59.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Dec 2019 09:59:58 -0800 (PST) From: Sean Turner Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Date: Thu, 19 Dec 2019 12:59:58 -0500 References: <0BC41077-FF1F-4C88-A5C9-93688EDF8E19@sn3rd.com> To: mls@ietf.org In-Reply-To: <0BC41077-FF1F-4C88-A5C9-93688EDF8E19@sn3rd.com> Message-Id: <68ED2BC3-1929-4413-B91B-25D377EE0816@sn3rd.com> X-Mailer: Apple Mail (2.3445.104.11) Archived-At: Subject: [MLS] REMINDER: Re: January 2020 Interim Registration and Issue discussion X-BeenThere: mls@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Messaging Layer Security List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Dec 2019 18:00:02 -0000 All, This is a friendly reminder that registration closes tomorrow for our = interim meeting. spt > On Dec 12, 2019, at 13:50, Sean Turner wrote: >=20 > The date and location are set for the January 2020 Interim meeting. It = will be on January 11th and 12th in New York, New York (the specific = location is being worked now). More details can be found on Github: = https://github.com/mlswg/wg-materials/tree/master/interim-2020-01. >=20 > Please register with the following form if you intend on attending = either remotely or in person. > Registration Link (https://forms.gle/ktUTg1V3hJzkyXMv8) >=20 > Registration deadline closes on December 20th. >=20 > We are soliciting proposals for presentations to add to the agenda for = the meeting. Please send proposals to mls-chairs@ietf.org. Due to time = limitations, these should be restricted to discussions about current = active drafts. >=20 > Here are the active documents: > Protocol (https://datatracker.ietf.org/doc/draft-ietf-mls-protocol/) > Issues: https://github.com/mlswg/mls-protocol/issues >=20 > Architecture = (https://datatracker.ietf.org/doc/draft-ietf-mls-architecture/) > Issues: https://github.com/mlswg/mls-architecture >=20 > Federation = https://datatracker.ietf.org/doc/draft-omara-mls-federation/) > Issues: https://github.com/mlswg/mls-federation/issues >=20 >=20 > We encourage the authors and other participants to read these issues, = distill the main questions raised by them and propose answers for = discussion on the list in the coming weeks. >=20 > Nick and Sean >=20 >=20 > Nick and Sean