Re: [TLS] Comments on TLS-ECJ-PAKE draft

"Dan Harkins" <dharkins@lounge.org> Mon, 18 July 2016 10:06 UTC

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Date: Mon, 18 Jul 2016 03:06:26 -0700 (PDT)
From: "Dan Harkins" <dharkins@lounge.org>
To: robert.cragie@gridmerge.com
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Subject: Re: [TLS] Comments on TLS-ECJ-PAKE draft
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  Hi Robert,

  This draft moves the NamedCurve/EllipticCurveList into the
ClientHello, and since the client sends X1 and ZKP(X1) in the
ClientHello it means that is going to be a list of 1. It basically
moves the client's key exchange portion from ClientKeyExchange into
ClientHello. So basically, if a client wants to do TLS-ECJ-PAKE
then that's the only thing it can offer and the parameters of
that exchange are all selected by the client, not the server.

  This is a fundamental change to TLS. If it's going to be offered,
it's the only thing that can be offered and therefore the only thing
that can be used. Seems like for a deployment either it's never used
or it's the only thing used and that makes it sort of a proprietary
protocol, not TLS.

  Dan.

On Thu, June 16, 2016 2:51 am, Robert Cragie wrote:
> I would like to ask the working group for comments on the TLS-ECJ-PAKE
> draft:
>
> https://tools.ietf.org/html/draft-cragie-tls-ecjpake-00
>
> Some brief notes:
>
> * This intended status is informational.
> * The draft is based on TLS/DTLS 1.2 as the Thread group required basis on
> existing RFCs wherever possible. For that reason and due to the WGs focus
> on TLS 1.3, I have understood from the chairs that it would not have
> received a great deal of attention from the WG, hence the intended status
> of informational.
> * The draft reflects the current use of the TLS_ECJPAKE_WITH_AES_128_CCM_8
> cipher suite in Thread (http://threadgroup.org/).
> * There is an experimental implementation in mbed TLS (
> https://github.com/ARMmbed/mbedtls)
> * The Thread group would like to get IANA assignments for 4 cipher suite
> values and one ExtensionType value as soon as possible.
> * There are at least four independent implementations, which have been
> used
> in interop. testing over the last 18 months.
> * The security considerations recommend restriction of the use of this
> cipher suite to Thread and similar applications and recommends it should
> not be used with web browsers and servers (mainly due to the long
> discussions regarding the use of PAKEs on this and other mailing lists).
>
> Robert
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