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Message-ID: <8576d112-c898-410c-6444-56c14bd8607c@suse.de>
Date:   Mon, 21 Feb 2022 15:20:20 +0100
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Subject: Re: [PATCH v4 15/15] crypto: dh - calculate Q from P for the full
 public key verification
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To:     Nicolai Stange <nstange@suse.de>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>
Cc:     =?UTF-8?Q?Stephan_M=c3=bcller?= <smueller@chronox.de>,
        Torsten Duwe <duwe@suse.de>,
        David Howells <dhowells@redhat.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        keyrings@vger.kernel.org
References: <20220221121101.1615-1-nstange@suse.de>
 <20220221121101.1615-16-nstange@suse.de>
From:   Hannes Reinecke <hare@suse.de>
In-Reply-To: <20220221121101.1615-16-nstange@suse.de>
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On 2/21/22 13:11, Nicolai Stange wrote:
> As the ->q in struct dh_ctx gets never set anywhere, the code in
> dh_is_pubkey_valid() for doing the full public key validation in accordance
> to SP800-56Arev3 is effectively dead.
> 
> However, for safe-prime groups Q = (P - 1)/2 by definition and
> as the safe-prime groups are the only possible groups in FIPS mode (via
> those ffdheXYZ() templates), this enables dh_is_pubkey_valid() to calculate
> Q on the fly for these.
> Implement this.
> 
> With this change, the last code accessing struct dh_ctx's ->q is now gone.
> Remove this member from struct dh_ctx.
> 
> Signed-off-by: Nicolai Stange <nstange@suse.de>
> ---
>   crypto/dh.c | 40 +++++++++++++++++++++++++++++-----------
>   1 file changed, 29 insertions(+), 11 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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