Re: [TLS] Would there be security issues with a 0-RTT resume?

Eric Rescorla <ekr@rtfm.com> Sun, 06 December 2015 00:47 UTC

Return-Path: <ekr@rtfm.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 3EFF61ACE01 for <tls@ietfa.amsl.com>; Sat, 5 Dec 2015 16:47:41 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.277
X-Spam-Level:
X-Spam-Status: No, score=-1.277 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, FM_FORGED_GMAIL=0.622, HTML_MESSAGE=0.001] autolearn=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 VqOtYupkJxeS for <tls@ietfa.amsl.com>; Sat, 5 Dec 2015 16:47:40 -0800 (PST)
Received: from mail-yk0-x236.google.com (mail-yk0-x236.google.com [IPv6:2607:f8b0:4002:c07::236]) (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 0C6701ACDEE for <TLS@ietf.org>; Sat, 5 Dec 2015 16:47:40 -0800 (PST)
Received: by ykdv3 with SMTP id v3so161029644ykd.0 for <TLS@ietf.org>; Sat, 05 Dec 2015 16:47:39 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rtfm-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=9CRk3XupC5O1bRbQI2yQHYpM3Ygq9Np/lHYqPTmGkCw=; b=G/1Vrps+LeaeZgVGTt4PLHST4H/4kzU7L4lF5GSANZQgfPc8BRJkwgQLX7MduEXKue CpQWIbYXcwxb1jbvpgvhzNQAhl87nGjH6pKfbcUrIwAqRjppEyYGde7i8ELNEX0ILeeD IUlxyg/7cto2ezWlbxAj8takfYDSzdGdHCUKKVk6q7QyyplRo9yUH6VIcbTNzkv2Kq/O MLXcT7/los148/b96aXA1YgvnokXg59QDm85pp2g7HM2bbYEJtfKg72RcnV7IhwteoA+ 7n3lRO4Tj5fwPoE/8FZvfDH47UrcWl+FFVzNwDMLBSg//E3n+H1cvHdnEV3iAcKidODE inRQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=9CRk3XupC5O1bRbQI2yQHYpM3Ygq9Np/lHYqPTmGkCw=; b=N6nXhusxuQgWQMlBS3kr0W/CGErJhG4LcAmcTAA5ofhQ+Is6C8EXzxsZjAKLw7IXsx 2q7vDiylFi/f+9mHkoJiDmxblHBwplPOe9UeRBUah16/GpS400APbAKhL2v6MH6/IcMQ O40if2eLUIqsk3zvjjxNJ4XMDW548Y8wQQ2CYFk1nlZKcWq5RuTFAa6bPA13kxOP/NZM SqccreOyd91i9ff8slw0jLgwbr4hn1+TYqIuFf/Y+NhKsaoccDyyRzeiiay1CJnQYBKa 9usk7lhE5VtdJY4iKuNbFx7UDF/jrqfm+bGKUCh18SOclDNdocKEYl+4nkXGVC7OyQ3o hB+A==
X-Gm-Message-State: ALoCoQkyCEWF+0NYKR432GttDROWqyF88XWb15p6cuDlAnVhUyO6aoPkbhVV7TDAbQ6bvxOHkx6e
X-Received: by 10.129.73.198 with SMTP id w189mr18869687ywa.223.1449362859317; Sat, 05 Dec 2015 16:47:39 -0800 (PST)
MIME-Version: 1.0
Received: by 10.13.249.197 with HTTP; Sat, 5 Dec 2015 16:46:59 -0800 (PST)
In-Reply-To: <CAH9QtQHtiuKnYoYoDpiNVz31HZH23sv9Bt-Rya985tWHorhcYA@mail.gmail.com>
References: <CAH9QtQHtiuKnYoYoDpiNVz31HZH23sv9Bt-Rya985tWHorhcYA@mail.gmail.com>
From: Eric Rescorla <ekr@rtfm.com>
Date: Sat, 5 Dec 2015 16:46:59 -0800
Message-ID: <CABcZeBOujQ2Q5NoCOuQ3skyqDDs72-=P07k1WTZSDgMJWti+gQ@mail.gmail.com>
To: Bill Cox <waywardgeek@google.com>
Content-Type: multipart/alternative; boundary=001a114dc814618e37052630161d
Archived-At: <http://mailarchive.ietf.org/arch/msg/tls/nGTyXXgPOSJeI-O8t0mCf2ua8oE>
Cc: "tls@ietf.org" <TLS@ietf.org>
Subject: Re: [TLS] Would there be security issues with a 0-RTT resume?
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: "This is the mailing list for the Transport Layer Security working group of the IETF." <tls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tls>, <mailto:tls-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tls/>
List-Post: <mailto:tls@ietf.org>
List-Help: <mailto:tls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tls>, <mailto:tls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 06 Dec 2015 00:47:41 -0000

On Sat, Dec 5, 2015 at 4:24 PM, Bill Cox <waywardgeek@google.com> wrote:

> I am not sure why we have a 0-RTT connect, but only a 1-RTT resume.  If
> anything, it seems like it would be easier to have a secure 0-RTT resume
> than a 0-RTT connect, though the 0-RTT connect does use some information
> from prior connections.
>
> Is there a good reason for having only a 0-RTT connect, and not resume?
>

The intention *is* to have a 0-RTT resume, since PSK and 0-RTT should be
compatible. The spec may not be entirely clear on this point, though.

-Ekr

Thanks,
> Bill
>
> _______________________________________________
> TLS mailing list
> TLS@ietf.org
> https://www.ietf.org/mailman/listinfo/tls
>
>