Received-SPF: pass (google.com: domain of linux-crypto+bounces-2726-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Precedence: bulk
Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8
Date: Mon, 18 Mar 2024 23:06:22 +0200
Message-Id: <CZX6K8KC480D.12UJ5ZTZZU55K@kernel.org>
Subject: Re: [PATCH v6 09/13] crypto: ecdsa - Replace ndigits with nbits
 where precision is needed
From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Stefan Berger" <stefanb@linux.vnet.ibm.com>,
 <keyrings@vger.kernel.org>, <linux-crypto@vger.kernel.org>,
 <herbert@gondor.apana.org.au>, <davem@davemloft.net>
Cc: <linux-kernel@vger.kernel.org>, <saulo.alessandre@tse.jus.br>,
 <lukas@wunner.de>, <bbhushan2@marvell.com>, "Stefan Berger"
 <stefanb@linux.ibm.com>
References: <20240312183618.1211745-1-stefanb@linux.vnet.ibm.com>
 <20240312183618.1211745-10-stefanb@linux.vnet.ibm.com>
In-Reply-To: <20240312183618.1211745-10-stefanb@linux.vnet.ibm.com>

On Tue Mar 12, 2024 at 8:36 PM EET, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.ibm.com>
>
> Replace the usage of ndigits with nbits where more precise space
> calculations are needed, such as in ecdsa_max_size where the length of a
> coordinate is determined.

What does "more precise" mean?

>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> Tested-by: Lukas Wunner <lukas@wunner.de>
> ---
>  crypto/ecdsa.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
> index 1814f009f971..4daefb40c37a 100644
> --- a/crypto/ecdsa.c
> +++ b/crypto/ecdsa.c
> @@ -266,7 +266,7 @@ static unsigned int ecdsa_max_size(struct crypto_akci=
pher *tfm)
>  {
>  	struct ecc_ctx *ctx =3D akcipher_tfm_ctx(tfm);
> =20
> -	return ctx->pub_key.ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
> +	return DIV_ROUND_UP(ctx->curve->nbits, 8);
>  }
> =20
>  static int ecdsa_nist_p384_init_tfm(struct crypto_akcipher *tfm)

BR, Jarkko