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From:   Stephan Mueller <smueller@chronox.de>
To:     Stephan =?ISO-8859-1?Q?M=FCller?= <smueller@chronox.de>,
        herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org,
        Marcelo Cerri <marcelo.cerri@canonical.com>,
        Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
        ard.biesheuvel@linaro.org, nhorman@redhat.com, simo@redhat.com
Subject: Re: [PATCH v2 5/5] crypto: ECDH SP800-56A rev 3 local public key validation
Date:   Mon, 13 Jul 2020 07:04:39 +0200
Message-ID: <5856902.DvuYhMxLoT@tauon.chronox.de>
In-Reply-To: <20200712180613.dkzaklumuxndpgfw@altlinux.org>
References: <2543601.mvXUDI8C0e@positron.chronox.de> <3168469.44csPzL39Z@positron.chronox.de> <20200712180613.dkzaklumuxndpgfw@altlinux.org>
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Am Sonntag, 12. Juli 2020, 20:06:13 CEST schrieb Vitaly Chikunov:

Hi Vitaly,

> Stephan,
>=20
> On Sun, Jul 12, 2020 at 06:42:14PM +0200, Stephan M=FCller wrote:
> > After the generation of a local public key, SP800-56A rev 3 section
> > 5.6.2.1.3 mandates a validation of that key with a full validation
> > compliant to section 5.6.2.3.3.
> >=20
> > Only if the full validation passes, the key is allowed to be used.
> >=20
> > The patch adds the full key validation compliant to 5.6.2.3.3 and
> > performs the required check on the generated public key.
> >=20
> > Signed-off-by: Stephan Mueller <smueller@chronox.de>
> > ---
> >=20
> >  crypto/ecc.c | 31 ++++++++++++++++++++++++++++++-
> >  crypto/ecc.h | 14 ++++++++++++++
> >  2 files changed, 44 insertions(+), 1 deletion(-)
> >=20
> > diff --git a/crypto/ecc.c b/crypto/ecc.c
> > index 52e2d49262f2..7308487e7c55 100644
> > --- a/crypto/ecc.c
> > +++ b/crypto/ecc.c
> > @@ -1404,7 +1404,9 @@ int ecc_make_pub_key(unsigned int curve_id, unsig=
ned
> > int ndigits,>=20
> >  	}
> >  =09
> >  	ecc_point_mult(pk, &curve->g, priv, NULL, curve, ndigits);
> >=20
> > -	if (ecc_point_is_zero(pk)) {
> > +
> > +	/* SP800-56A rev 3 5.6.2.1.3 key check */
> > +	if (ecc_is_pubkey_valid_full(curve, pk)) {
> >=20
> >  		ret =3D -EAGAIN;
> >  		goto err_free_point;
> >  =09
> >  	}
> >=20
> > @@ -1452,6 +1454,33 @@ int ecc_is_pubkey_valid_partial(const struct
> > ecc_curve *curve,>=20
> >  }
> >  EXPORT_SYMBOL(ecc_is_pubkey_valid_partial);
> >=20
> > +/* SP800-56A section 5.6.2.3.3 full verification */
>=20
> Btw, 5.6.2.3.3 is partial validation, 5.6.2.3.2 is full validation
> routine.

Looking at SP800-56A revision 3 from April 2018 I see:

"5.6.2.3.3 ECC Full Public-Key Validation Routine"

Thanks for the review.

Ciao
Stephan