Re: [Cfrg] Fwd: I-D Action: draft-turner-thecurve25519function-00.txt

[Benjamin Black <[e-mail]>]

On Wed, Jul 30, 2014 at 11:16 AM, Phillip Hallam-Baker <
[e-mail]> wrote:

> On Wed, Jul 30, 2014 at 2:05 PM, Randy Bush <[e-mail]> wrote:
> > sean, we also need signatures.  would you consider adding ed25519 to
> > this draft or doing a parallel draft?
>
> We do need signatures, but do we need curve 25519 signatures?
>
>
Using the same curve across kx and signatures simplifies specification,
implementation, and deployment.


>
> RSA allows one key to be used for encryption and signature easily. But
> that is still terrible security practice.
>
>
I don't see how this is relevant to using the same curves in different
algorithms.


> Looking through the sets of requirements we have, a curve optimized
> for encryption may not be best for signatures. And writing up how to
> do signatures from a curve is non-trivial (unless its 'do DSA with
> this curve')
>
>
Specific to Randy's request, EdDSA is specified in the same paper as
ed25519.


> Given that the EC keys are short, we could have a combined 'encryption
> and signature' certificate  but with different curves for each one.
>
>
The discussion is about using the same curves in different algorithms.
Curves are not keys.


b