Re: [saag] AD review of draft-iab-crypto-alg-agility-06

Eliot Lear <> Thu, 03 September 2015 11:56 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id 6716D1B3633 for <>; Thu, 3 Sep 2015 04:56:10 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -14.511
X-Spam-Status: No, score=-14.511 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_HI=-5, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id ZPR-kU-_cMs0 for <>; Thu, 3 Sep 2015 04:56:09 -0700 (PDT)
Received: from ( []) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id B6CF61B32C9 for <>; Thu, 3 Sep 2015 04:56:08 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;;; l=2043; q=dns/txt; s=iport; t=1441281368; x=1442490968; h=subject:to:references:from:message-id:date:mime-version: in-reply-to; bh=DQnmxNeUiY8a+pKkt8SQchIvBYdge1gKnPWlt2xNlOI=; b=Is8HOPM8aiilASstEa79vTW9TezHCEWhpLw8RVgDXFTueGZv0CWeREdj R0E1+DdUGGYDB+vX8sXjp7sO5RxPxHjadJZd3bMwZPz1dSh+m63f3IIXA Ix4z2LzBIz6rFCGhWehEPmVa7V+Ln6L8Tj6UDG3Zsa9LBH+HehtDQFawQ s=;
X-Files: signature.asc : 481
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-AV: E=Sophos;i="5.17,461,1437436800"; d="asc'?scan'208";a="611363638"
Received: from (HELO ([]) by with ESMTP; 03 Sep 2015 11:56:05 +0000
Received: from [] ( []) by (8.14.5/8.14.5) with ESMTP id t83Bu5hH019889; Thu, 3 Sep 2015 11:56:05 GMT
To: Russ Housley <>,
References: <> <> <>
From: Eliot Lear <>
X-Enigmail-Draft-Status: N1110
Message-ID: <>
Date: Thu, 3 Sep 2015 13:56:04 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.2.0
MIME-Version: 1.0
In-Reply-To: <>
Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="H7xnUmKbndAJUs6Pu4W5luGIDK6a6xE7B"
Archived-At: <>
Subject: Re: [saag] AD review of draft-iab-crypto-alg-agility-06
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Security Area Advisory Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 03 Sep 2015 11:56:10 -0000

Hi Russ,

Just one comment:

On 9/2/15 10:48 PM, Russ Housley wrote:
> Merging with comments from others, the current text is:
>    Without clear mechanisms for algorithm and suite transition,
>    preserving interoperability becomes a difficult social problem.  For
>    example, consider web browsers.  Dropping support for an algorithm
>    suite can break connectivity to some web sites, and the browser
>    vendor will lose users by doing so.  This situation creates
>    incentives to support algorithm suites that would otherwise be
>    deprecated in order to preserve interoperability.

Honestly this paragraph is confusing.  It's opaque because it's not
clear whether you're aiming at a strawman of where TLS doesn't support
agility or the case of long lived root or intermediate certificates.  If
it's the former, can you find a more current example?  And the last
sentence is just flat out ambiguous, although in an amusing sort of way
(who deprecates in order to preserve interoperability?).

I can't propose replacement text here because of the ambiguities...