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From:   Heiko Stuebner <heiko@sntech.de>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     palmer@dabbelt.com, paul.walmsley@sifive.com,
        aou@eecs.berkeley.edu, herbert@gondor.apana.org.au,
        davem@davemloft.net, conor.dooley@microchip.com,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-crypto@vger.kernel.org, christoph.muellner@vrull.eu,
        Heiko Stuebner <heiko.stuebner@vrull.eu>
Subject: Re: [PATCH v5 0/4] Implement GCM ghash using Zbc and Zbkb extensions
Date:   Mon, 10 Jul 2023 11:44:56 +0200
Message-ID: <5381895.Sb9uPGUboI@phil>
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 <20230613030216.GC883@sol.localdomain>
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Hi Eric,

Am Dienstag, 13. Juni 2023, 05:02:16 CEST schrieb Eric Biggers:
> Hi Heiko,
> 
> On Mon, Jun 12, 2023 at 11:04:38PM +0200, Heiko Stuebner wrote:
> > From: Heiko Stuebner <heiko.stuebner@vrull.eu>
> > 
> > This was originally part of my vector crypto series, but was part
> > of a separate openssl merge request implementing GCM ghash as using
> > non-vector extensions.
> > 
> > As that pull-request
> >     https://github.com/openssl/openssl/pull/20078
> > got merged recently into openssl, we could also check if this could
> > go into the kernel as well and provide a base for further accelerated
> > cryptographic support.
> 
> I'm still a bit skeptical of the usefulness of a standalone "ghash"
> implementation, when in practice it will only be used as part of "gcm(aes)".
> Directly implementing "gcm(aes)" (instead of relying on crypto/gcm.c to compose
> "ghash" and "ctr(aes)") also allows some performance optimizations.
> 
> I asked about this on v4
> (https://lore.kernel.org/linux-crypto/ZCSG71bRuTzVutdm@gmail.com/),
> but I didn't receive a response.
> 
> Any thoughts on this?

somehow I always seem to overlook this when adapting the series :-(

I guess for me the main gcm was always a stepping stone to get
started and extend later. This is my first rodeo with crypto stuff
in the kernel, so this looks like a manageable chunk and as can be
seen by the discussion we had about licensing brings enough topics
on its own :-) .


Heiko