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Date:   Mon, 5 Nov 2018 21:23:14 +0300
From:   Vitaly Chikunov <vt@altlinux.org>
To:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/3] crypto: streebog - add Streebog hash function
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        Herbert Xu <herbert@gondor.apana.org.au>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Philippe Ombredanne <pombredanne@nexb.com>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" <linux-crypto@vger.kernel.org>,
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Ard,

On Mon, Nov 05, 2018 at 02:22:21PM +0100, Ard Biesheuvel wrote:
> 
> > +static const struct streebog_uint512 buffer512 = { {
> > +       cpu_to_le64(0x200ULL),
> 
> Can we keep the memory representation in native endianness, and only
> swab the in/output [where needed]?

I hope you do not insist on that?

The code is using same primitives to add/xor/permute with data from
these arrays (buffer512[] and C[], those which use cpu_to_le64), and
from generic data buffers. Having these arrays in native endianness will
cause complexities - code split and duplications. For example, XLPS
permutation will require two versions, with one accessing (y) as is and
another as cpu_to_le64(y).

The code is based on canonical implementation by RFC 6986 ("GOST R
34.11-2012: Hash Function") author, and I don't want it do deviate that
much from the original, which would complicate algorithm reviews.

Thanks,