Re: [TLS] I-D Action: draft-ietf-tls-curve25519-00.txt

Simon Josefsson <simon@josefsson.org> Mon, 15 June 2015 21:13 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: Eric Rescorla <ekr@rtfm.com>
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Date: Mon, 15 Jun 2015 23:12:16 +0200
In-Reply-To: <CABcZeBOTmw0eXopDoOqOKVgT9_ftzKVj_8T9ftfF6NJjsL+Waw@mail.gmail.com> (Eric Rescorla's message of "Fri, 12 Jun 2015 16:04:48 -0400")
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Subject: Re: [TLS] I-D Action: draft-ietf-tls-curve25519-00.txt
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Eric Rescorla <ekr@rtfm.com> writes:

>> "This section defines a new point format suitable to encode Curve25519
>> public keys, as well as an identifier to negotiate this new format in
>> TLS, and includes guidance on their use."
>>
>> Is this format going to be the chosen one for TLS 1.3? Because TLS 1.3
>> can't negotiate point formats for ECDHE.
>>
>> Also, I don't see the value of trying to negotiate the point format,
>> and I think that the negotiation will act as an implementation error
>> source.
>
>
> I would suggest claiming that this point format is "uncompressed" and the
> only point format for Curve25519.

I'm happy to do that.  Anyone against?  If I understand correctly, I
would drop most of the montgomery_x_le ECPointFormat registration and
instead say: use ECPointFormat "uncompressed" and send the public-key
formatted as follows [...].

/Simon