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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Thu, 28 Jan 2021 11:30:23 +0100
Message-ID: <CAMj1kXHvY9JveFyhtETALCH=AFGMGVbGGFMNDGc6ZVngEKbyDQ@mail.gmail.com>
Subject: Re: [PATCH v7 4/7] crypto: add ecc curve and expose them
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Meng Yu <yumeng18@huawei.com>,
        "David S. Miller" <davem@davemloft.net>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Zaibo Xu <xuzaibo@huawei.com>, wangzhou1@hisilicon.com,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Daniele Alessandrelli <daniele.alessandrelli@linux.intel.com>,
        Mark Gross <mgross@linux.intel.com>,
        "Khurana, Prabhjot" <prabhjot.khurana@intel.com>,
        "Reshetova, Elena" <elena.reshetova@intel.com>
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On Thu, 28 Jan 2021 at 06:04, Herbert Xu <herbert@gondor.apana.org.au> 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?