Re: New confidentiality and integrity limits

Martin Thomson <mt@lowentropy.net> Thu, 25 June 2020 23:45 UTC

Return-Path: <mt@lowentropy.net>
X-Original-To: quic@ietfa.amsl.com
Delivered-To: quic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id AF7193A107B for <quic@ietfa.amsl.com>; Thu, 25 Jun 2020 16:45:17 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Level:
X-Spam-Status: No, score=-2.098 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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=lowentropy.net header.b=oMh0XLJV; dkim=pass (2048-bit key) header.d=messagingengine.com header.b=gEwg3tin
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 DyVnHqd-eMtx for <quic@ietfa.amsl.com>; Thu, 25 Jun 2020 16:45:15 -0700 (PDT)
Received: from wout1-smtp.messagingengine.com (wout1-smtp.messagingengine.com [64.147.123.24]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id D8C613A1053 for <quic@ietf.org>; Thu, 25 Jun 2020 16:45:15 -0700 (PDT)
Received: from compute2.internal (compute2.nyi.internal [10.202.2.42]) by mailout.west.internal (Postfix) with ESMTP id 17105830 for <quic@ietf.org>; Thu, 25 Jun 2020 19:45:15 -0400 (EDT)
Received: from imap2 ([10.202.2.52]) by compute2.internal (MEProxy); Thu, 25 Jun 2020 19:45:15 -0400
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lowentropy.net; h=mime-version:message-id:in-reply-to:references:date:from:to :subject:content-type; s=fm2; bh=6Fjl5PFOdfrFQSGF25brJhGie0nZ8Vh 0fi5mL1fq2eA=; b=oMh0XLJVlfqRR8BJlDP5c3lx2kGUFT0TXnI39dqi//RbCTL IENnrnloGm1mnl68/2kCcRnhkV/mEkG6TP8ibODWpELc3NQ8he3CkyaADecRGucO TUTn3/1WL6L7htXKV2txcPy4sMw/2VQxWU7Am9KXA/iaNFX6U5W4NJZVgPZxienm Yjb5nrNfB9K5rpZXxwz8I28MEsLOoBEi2SEGJ81nS4JPRv7UYL/XHVon3+bi9VN9 R+AK/QQKemqvFqzV+/jT0m4s3xQzFsVvifo01ppSOEOGf8NxOltnXhm+0okZoRmg hKWHIjq6D8Q9P28OAAp725x+JPq8Bypwy00xMHA==
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=6Fjl5P FOdfrFQSGF25brJhGie0nZ8Vh0fi5mL1fq2eA=; b=gEwg3tinDPVXBHsJ35XsSg nCwDAjk8H4IJcD3pDpGYoqTehk8x+6KKjn55EZOZkedF9Lf6z+jrB+5K2Y4wNQ1Q sR6JoULb1CppKxkD+a1Lk2qgiaPR6OVkYGQfiWYppoDom5Pi4EVetSQ/NGk6IBl9 AzHWKugg6vh78QK+BJnRknXjQ1IygVvw/VNT0ijjedfV0pPit4YY/nGwl5cRX1ya CAWsTRK71ZNuHu4lryS7JRPHkPZhhbjqyyTxKhBDRutz/1crDm2gNlNiE3c+8WB3 Ya6KoPgyADgdiSNeYYcMM77KTfclf61Pz6ck0CYBpHWfkBGIQbzYBhi5VRKOESog ==
X-ME-Sender: <xms:Cjf1XnO0tBF91zDUwYmoK4IxMPYQ5G0We-r73jOPqTYPPWs-AyaCkQ>
X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedrudeltddgvdegucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefofgggkfgjfhffhffvufgtsehttd ertderredtnecuhfhrohhmpedfofgrrhhtihhnucfvhhhomhhsohhnfdcuoehmtheslhho figvnhhtrhhophihrdhnvghtqeenucggtffrrghtthgvrhhnpeekteeuieektdekleefke evhfekffevvdevgfekgfeluefgvdejjeegffeigedtjeenucevlhhushhtvghrufhiiigv pedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehmtheslhhofigvnhhtrhhophihrdhnvg ht
X-ME-Proxy: <xmx:Cjf1Xh9DCkC9A7bYf6dIegqQIR5r4jlhw2gP5rSYEKQs1H1RR2VVWw> <xmx:Cjf1XmTGoDZoyMXjUHekv2MBohpuCWPx5oxk4I-TpHAndzhrdu3-5A> <xmx:Cjf1Xru8xZWDtjsRXdmhDtvdgECZ84uE6U_sP1kQOBhKl9W1ul3emQ> <xmx:Cjf1Xi-Ye7uqV54K-nIyNNudHaSOa_PDjK11DmTM5hmGkQoNp7SASQ>
Received: by mailuser.nyi.internal (Postfix, from userid 501) id 488A8E00A8; Thu, 25 Jun 2020 19:45:14 -0400 (EDT)
X-Mailer: MessagingEngine.com Webmail Interface
User-Agent: Cyrus-JMAP/3.3.0-dev0-543-gda70334-fm-20200618.004-gda703345
Mime-Version: 1.0
Message-Id: <1d543593-7abc-4a89-93c5-82c464492786@www.fastmail.com>
In-Reply-To: <58b40fc0-86ad-49e9-bc17-187c38e97f7a@www.fastmail.com>
References: <43bb1525-0afa-4c4e-a234-f6ccfacbdd29@www.fastmail.com> <a4d7e8cf-5879-6941-e059-5d2f3e67ae86@huitema.net> <58b40fc0-86ad-49e9-bc17-187c38e97f7a@www.fastmail.com>
Date: Fri, 26 Jun 2020 09:44:55 +1000
From: "Martin Thomson" <mt@lowentropy.net>
To: quic@ietf.org
Subject: Re: New confidentiality and integrity limits
Content-Type: text/plain
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic/e53V1ZDhk_dlnaEa4w_Qs8cNk8Y>
X-BeenThere: quic@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Main mailing list of the IETF QUIC working group <quic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic>, <mailto:quic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic/>
List-Post: <mailto:quic@ietf.org>
List-Help: <mailto:quic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic>, <mailto:quic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 25 Jun 2020 23:45:18 -0000

On Fri, Jun 26, 2020, at 04:29, Christopher Wood wrote:
> As Martin noted, for the integrity limit, the story is slightly 
> different. Key updates do not help there.

Or we don't know that they do...  There are still a lot of unanswered questions.  We do know that a forgery attempt against one key is likely still good for a different key on the same connection.  It might not be good for another connection (the inclusion of connection IDs might help us here, but that's another unknown - and unreliable - factor) but we can't really control for that.  So we chose something we believe to be both conservative and practical.

The forgery limits are still quite generous: if you have to drop a connection due to that many forgeries, then I'd suggest that something is seriously wrong.