linux-kernel - Re: [PATCH 0/7] crypto: add eddsa support for x509(Internet mail)

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Date:   Tue, 18 May 2021 21:57:32 +0800
From:   hongbo li <herbert.tencent@...il.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     herberthbli(李弘博) 
        <herberthbli@...cent.com>,
        "keyrings@...r.kernel.org" <keyrings@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "dhowells@...hat.com" <dhowells@...hat.com>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "tianjia.zhang@...ux.alibaba.com" <tianjia.zhang@...ux.alibaba.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/7] crypto: add eddsa support for x509(Internet mail)

Eric Biggers <ebiggers@...nel.org> 于2021年5月18日周二 上午5:21写道：
>
> On Thu, May 13, 2021 at 02:44:07PM +0000, herberthbli(李弘博) wrote:
> > 在 2021/5/13 3:12, Eric Biggers 写道:
> >
> > On Wed, May 12, 2021 at 10:04:07PM +0800, Hongbo Li wrote:
> >
> >
> > From: Hongbo Li <herberthbli@...cent.com><mailto:herberthbli@...cent.com>
> >
> > This series of patches add support for x509 cert signed by eddsa,
> > which is described in RFC8032 [1], currently ed25519 only.
> >
> >
> >
> > It would be helpful to explain how this is related to the kernel's existing
> > Curve25519 support.
> >
> > - Eric
> >
> >
> > Curve25519 is an elliptic curve used for key agreement(ECDH). It is a Montgomery curve.
> >
> > Edwards25519 is a twisted Edwards curve and birationally equivalent to Curve25519, the
> > birational maps are described in rfc7748 section 4.1.
> > https://datatracker.ietf.org/doc/html/rfc7748#section-4.1
> >
> >
> > Ed25519 is a Digital Signature Algorithm over Edwards25519.
> >
>
> Sure, but what does that mean in terms of code.  Can you reuse any of the code,
> and if not why not?  I *think* the answer is no, but this is a common point of
> confusion, so it would be helpful to properly explain this...
>
> - Eric

Thank you for your review. No, the eddsa can't reuse the code of curve25519.
I'll also explain this in the next version of patches.
Regards,
Hongbo