Re: [PATCH v6 09/13] crypto: ecdsa - Replace ndigits with nbits where precision is needed

[Jarkko Sakkinen]

On Tue Mar 12, 2024 at 8:36 PM EET, Stefan Berger wrote:
> From: Stefan Berger <stefanb@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxx>
> Tested-by: Lukas Wunner <lukas@xxxxxxxxx>
> ---
>  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_akcipher *tfm)
>  {
>  	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
>  
> -	return ctx->pub_key.ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
> +	return DIV_ROUND_UP(ctx->curve->nbits, 8);
>  }
>  
>  static int ecdsa_nist_p384_init_tfm(struct crypto_akcipher *tfm)

BR, Jarkko