Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220729165954.991-1-ignat@cloudflare.com> <Yv9dvvy0rK/1T0sU@gondor.apana.org.au>
In-Reply-To: <Yv9dvvy0rK/1T0sU@gondor.apana.org.au>
From:   Ignat Korchagin <ignat@cloudflare.com>
Date:   Mon, 29 Aug 2022 11:48:23 +0100
Message-ID: <CALrw=nEh7LX3DSCa3FTu8BYr4QWx+W2h3Jei9Qo67+XXH-Vegw@mail.gmail.com>
Subject: Re: [PATCH] crypto: akcipher - default implementations for setting
 private/public keys
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     "David S . Miller" <davem@davemloft.net>,
        linux-crypto <linux-crypto@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        kernel-team <kernel-team@cloudflare.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Aug 19, 2022 at 10:54 AM Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Fri, Jul 29, 2022 at 05:59:54PM +0100, Ignat Korchagin wrote:
> >
> > @@ -132,6 +138,10 @@ int crypto_register_akcipher(struct akcipher_alg *alg)
> >               alg->encrypt = akcipher_default_op;
> >       if (!alg->decrypt)
> >               alg->decrypt = akcipher_default_op;
> > +     if (!alg->set_priv_key)
> > +             alg->set_priv_key = akcipher_default_set_key;
> > +     if (!alg->set_pub_key)
> > +             alg->set_pub_key = akcipher_default_set_key;
>
> Under what circumstances could we have an algorithm without a
> set_pub_key function?

I can only elaborate here as I didn't encounter any real-world
use-cases, but may assume some limited crypto hardware device, which
may somehow "encourage" doing public key operations in software and
providing only "private-key" operations due to its limited resources.

Ignat

> Cheers,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt