[TLS] ALPN - specifying client preference

Ashok Kumar <ashokkumar.j@gmail.com> Tue, 09 April 2013 06:41 UTC

Return-Path: <ashokkumar.j@gmail.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (localhost []) by ietfa.amsl.com (Postfix) with ESMTP id D444021F859C for <tls@ietfa.amsl.com>; Mon, 8 Apr 2013 23:41:49 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.598
X-Spam-Status: No, score=-3.598 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([]) by localhost (ietfa.amsl.com []) (amavisd-new, port 10024) with ESMTP id NK6Yq4yJUaiE for <tls@ietfa.amsl.com>; Mon, 8 Apr 2013 23:41:49 -0700 (PDT)
Received: from mail-ve0-f177.google.com (mail-ve0-f177.google.com []) by ietfa.amsl.com (Postfix) with ESMTP id 3107321F8FA5 for <tls@ietf.org>; Mon, 8 Apr 2013 23:41:49 -0700 (PDT)
Received: by mail-ve0-f177.google.com with SMTP id jw11so6056288veb.8 for <tls@ietf.org>; Mon, 08 Apr 2013 23:41:48 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:date:message-id:subject:from:to :content-type; bh=Y+fHp5YE9r1wy2Aqajlt0ipIfA+Ki3NUGf/yz8j2O5o=; b=K3qhhWeQhph6uN/47ZYScpxVBbD8yZcrs9jeXIO1VQTvwayOyYqmc6DsxlA0RO/eaR pZifTIiifRzoflg2LRDXQlNBg0CaYoRcnqEPtccpO2Iuw6Vo2XUEYU8+rSfBTgvm6beT Z09yb+XDtz0WymJplcKc23ee43FieuAi0XlP0sVPFtJZhmXrcTf4raRWhbP52IEFl9Fk mTjE89UiyXQbZXPwN9QFmMq+B19993B8N9iaZFspFsas0K5c+s5qMJlKfmmPFKVClbDC VgDK5VKIl11WXsXQGBQx76IV1swRIe136m+SWNmjqy0h0u1AZ74lFbfUCBHkYjtdCQqD cSBQ==
MIME-Version: 1.0
X-Received: by with SMTP id y6mr15537967vdi.19.1365489708651; Mon, 08 Apr 2013 23:41:48 -0700 (PDT)
Received: by with HTTP; Mon, 8 Apr 2013 23:41:48 -0700 (PDT)
Date: Tue, 9 Apr 2013 12:11:48 +0530
Message-ID: <CAOeYYRf4eJ0EHaWA-yfa+2GyvHQoqrXAY+e6aML6a1UCt9jhDg@mail.gmail.com>
From: Ashok Kumar <ashokkumar.j@gmail.com>
To: tls@ietf.org
Content-Type: multipart/alternative; boundary=20cf30780d62075b8a04d9e7d91a
Subject: [TLS] ALPN - specifying client preference
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.12
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: <http://www.ietf.org/mail-archive/web/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: Tue, 09 Apr 2013 06:41:50 -0000

With NPN, client could choose the protocol that it has better support for.

With ALPN, do we intend to add some mechanism where the client can specify
its preference? I believe the order in which the protocols are sent give
some preference, but is anyone interested in having options to say that
client prefers all protocols equally?


P.S.: I'm new to TLS list and apologize if the query is not relevant. I was
thinking more in lines of HTTP headers having qvalues.