Re: [PATCH v7 4/7] crypto: add ecc curve and expose them

[Ard Biesheuvel]

On Thu, 28 Jan 2021 at 06:04, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, Jan 22, 2021 at 03:09:52PM +0800, Meng Yu wrote:
> > 1. Add ecc curves(P224, P384, P521) for ECDH;
>
> OK I think this is getting unwieldy.
>
> In light of the fact that we already have hardware that supports
> a specific subset of curves, I think perhaps it would be better
> to move the curve ID from the key into the algorithm name instead.
>
> IOW, instead of allocating ecdh, you would allocate ecdh-nist-pXXX.
>
> Any comments?
>

Agreed. Bluetooth appears to be the only in-kernel user at the moment,
and it is hard coded to use p256, so it can be easily updated.

But this also begs the question which ecdh-nist-pXXX implementations
we actually need? Why are we exposing these curves in the first place?