[rtcweb] Open Security issue: Crypto algorithms

Harald Alvestrand <harald@alvestrand.no> Wed, 06 May 2015 09:53 UTC

Return-Path: <harald@alvestrand.no>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id E92341A7014 for <rtcweb@ietfa.amsl.com>; Wed, 6 May 2015 02:53:09 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.91
X-Spam-Level:
X-Spam-Status: No, score=-1.91 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01] autolearn=ham
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 bHa219-9Mm5P for <rtcweb@ietfa.amsl.com>; Wed, 6 May 2015 02:53:07 -0700 (PDT)
Received: from mork.alvestrand.no (mork.alvestrand.no [IPv6:2001:700:1:2::117]) by ietfa.amsl.com (Postfix) with ESMTP id 608531A01F9 for <rtcweb@ietf.org>; Wed, 6 May 2015 02:53:07 -0700 (PDT)
Received: from localhost (localhost [127.0.0.1]) by mork.alvestrand.no (Postfix) with ESMTP id 9249B7C4111 for <rtcweb@ietf.org>; Wed, 6 May 2015 11:53:06 +0200 (CEST)
X-Virus-Scanned: Debian amavisd-new at alvestrand.no
Received: from mork.alvestrand.no ([127.0.0.1]) by localhost (mork.alvestrand.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6IuDTgYlJ1br for <rtcweb@ietf.org>; Wed, 6 May 2015 11:53:05 +0200 (CEST)
Received: from hta-hippo.lul.corp.google.com (unknown [IPv6:2620:0:1043:1:a183:4e00:d5f4:a58c]) by mork.alvestrand.no (Postfix) with ESMTPSA id 4C9477C410E for <rtcweb@ietf.org>; Wed, 6 May 2015 11:53:05 +0200 (CEST)
Message-ID: <5549E480.4030806@alvestrand.no>
Date: Wed, 06 May 2015 11:53:04 +0200
From: Harald Alvestrand <harald@alvestrand.no>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0
MIME-Version: 1.0
To: "rtcweb@ietf.org" <rtcweb@ietf.org>
Content-Type: text/plain; charset="utf-8"; format="flowed"
Content-Transfer-Encoding: 7bit
Archived-At: <http://mailarchive.ietf.org/arch/msg/rtcweb/8FMfj9k6GBkr5WJ5YzTc9tORq_k>
Subject: [rtcweb] Open Security issue: Crypto algorithms
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb/>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 06 May 2015 09:53:10 -0000

security-arch-11 contains the following text:

    All implementations MUST implement DTLS 1.0, with the cipher suite
    TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA and the DTLS-SRTP protection
    profile SRTP_AES128_CM_HMAC_SHA1_80.  Implementations SHOULD
    implement DTLS 1.2 with the TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
    cipher suite.  Implementations SHOULD favor cipher suites which
    support PFS over non-PFS cipher suites and GCM over CBC cipher
    suites.  [[OPEN ISSUE: Should we require ECDSA?  Waiting for WG
    Consensus.]]


security-arch-10 contained the following text in the same spot:

    All implementations MUST implement both DTLS 1.2 and DTLS 1.0, with
    the cipher suites TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 and
    TLS_DHE_RSA_WITH_AES_128_CBC_SHA and the DTLS-SRTP protection profile
    SRTP_AES128_CM_HMAC_SHA1_80.  Implementations SHOULD favor cipher
    suites which support PFS over non-PFS cipher suites and GCM over CBC
    cipher suites.  [[OPEN ISSUE:  Should we require ECDHE?  Waiting for
    TLS WG Consensus.]]

So it seems that consensus has shifted from MUST for DHE_RSA to MUST for 
ECDHE_RSA (presumably based on a TLS WG consensus), with some arguing 
for inclusion of ECDSA in the mandatory ciphersuites, and has landed on 
DTLS 1.0 only being mandatory.

I tried to find the discussion in the archives, but failed - which makes 
it hard to have an opionion of where consensus is heading; there is a 
February note from Martin that's relevant, but that's all I found.

Minutes from last meetings are here:

https://tools.ietf.org/wg/rtcweb/minutes?item=minutes-92-rtcweb.html
https://tools.ietf.org/wg/rtcweb/minutes?item=minutes-91-rtcweb.html

I couldn't find anything relevant there either.

Do we have an idea on how to move forward with resolving the outstanding 
question?

(the trigger for the question is a colleague looking into the crypto 
code for our implementation; he would prefer to spend his time making 
sure the stuff we specify as mandatory works well.)

Harald