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Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt

Hanno Böck <hanno@hboeck.de> Thu, 02 October 2014 08:26 UTC

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Date: Thu, 02 Oct 2014 10:26:02 +0200
From: Hanno Böck <hanno@hboeck.de>
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Subject: Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
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Am Wed, 01 Oct 2014 16:12:54 -0700
schrieb internet-drafts@ietf.org:

>    This document requires that Transport Layer Security (TLS) clients
>    and servers never negotiate the use of RC4 cipher suites when they
>    establish connections.  This applies to all TLS versions, and
> updates [RFC5246], [RFC4346], and [RFC2246].

I really don't want to hold anything here and would welcome if this
gets finally out, however there's one thing that bothers me:
There is currently no such RFC for RC2 or DES. Both are - considering
current RFCs - perfectly valid ciphers according to RFC 2246.

It doesn't really make sense to forbid RC4 (likely weak, but no
public practical attacks yet) while still allowing RC2(40 bit)/DES
(practically broken).

Should we change this to "forbid RC2, DES and RC4" ?

(there's of course also the potential discussion if further ciphers
should be deprecated that are likely weak but not broken - things like
DSS - but I'd keep that discussion separate for now)

-- 
Hanno Böck
http://hboeck.de/

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