Re: [TLS] Status of Cha-Cha/Poly Cipher Suites?

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Sun, 17 May 2015 05:42 UTC

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Date: Sun, 17 May 2015 08:42:13 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Yoav Nir <ynir.ietf@gmail.com>
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Subject: Re: [TLS] Status of Cha-Cha/Poly Cipher Suites?
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On Sun, May 17, 2015 at 01:02:23AM +0300, Yoav Nir wrote:
> Hi, Jeffrey
> 
> The algorithm document has just been published: https
> 
> What remains for the TLS working group to do is to adopt a draft for
> ChaCha20-Poly1305 in TLS. There already is a candidate:
> https://tools.ietf.org/html/draft-mavrogiannopoulos-chacha-tls-05

The only comment I have regarding that draft is that it doesn't specify
what to stick to record payload. Ciphertext (|P| bytes) || Tag (16 bytes),
right?

> Once that’s done, the document can both progress and if needed, people
> can request early assignment of identifiers. The ciphersuite registry
> has a “specification required” policy. Strictly speaking, the private
> draft could be enough - we don’t have to have an RFC, but practically
> speaking, this document will only get assignment after it is adopted
> by the WG.

As note, GnuTLS 3.4.x implements (disabled by default) the abovementioned
draft, using CSID CCA0-CCA7 (which are noted in the draft).

> > On May 17, 2015, at 12:24 AM, Jeffrey Walton <noloader@gmail.com> wrote:
> > 
> > Lack of the cipher suite values is holding up OpenSSL's implementation. [1]
> > 
> > If the IETF considers Chrome (26% market share [2]) and Apache/OpenSSL
> > based servers (52% market share [3]), then it appears, then the cipher
> > suite values are long overdue.

Also, due to widespread use, the Chrome Chacha CSID CC13-CC15 could be marked
as "reserved" (or even given names), preferably with note pointing to
draft-agl-tls-chacha20poly1305-04 (there is perecedent for marking CSID as
reserved due to existing use). Those are not interoperable with the ones
in GnuTLS.


-Ilari