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Date:   Mon, 4 Jan 2021 22:31:48 +1100
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     "Reshetova, Elena" <elena.reshetova@intel.com>
Cc:     Daniele Alessandrelli <daniele.alessandrelli@linux.intel.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        "Alessandrelli, Daniele" <daniele.alessandrelli@intel.com>,
        Mark Gross <mgross@linux.intel.com>,
        "Khurana, Prabhjot" <prabhjot.khurana@intel.com>
Subject: Re: [RFC PATCH 0/6] Keem Bay OCS ECC crypto driver
Message-ID: <20210104113148.GA20575@gondor.apana.org.au>
References: <20201217172101.381772-1-daniele.alessandrelli@linux.intel.com>
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On Mon, Jan 04, 2021 at 08:04:15AM +0000, Reshetova, Elena wrote:
> > 2. The OCS ECC HW does not support the NIST P-192 curve. We were planning to
> >    add SW fallback for P-192 in the driver, but the Intel Crypto team
> >    (which, internally, has to approve any code involving cryptography)
> >    advised against it, because they consider P-192 weak. As a result, the
> >    driver is not passing crypto self-tests. Is there any possible solution
> >    to this? Is it reasonable to change the self-tests to only test the
> >    curves actually supported by the tested driver? (not fully sure how to do
> >    that).
> 
> An additional reason against the P-192 SW fallback is the fact that it can 
> potentially trigger unsafe behavior which is not even "visible" to the end user
> of the ECC functionality. If I request (by my developer mistake) a P-192 
> weaker curve from ECC Keem Bay HW driver, it is much safer to return a
> "not supported" error that proceed behind my back with a SW code
> implementation making me believe that I am actually getting a HW-backed up
> functionality (since I don't think there is a way for me to check that I am using
> SW fallback). 

Sorry, but if you break the Crypto API requirement then your driver
isn't getting merged.

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