Re: [edk2-devel] [PATCH v1 1/1] CryptoPkg/BaseCryptoLib: Remove unnecessary key generation.

["levi.yun" <yeoreum.yun@arm.com>]

Hi Li!

On 18/07/2023 07:03, Li, Yi1 wrote:
> Hi,
>
> This function has a special use case: when the input PublicKey array is NULL and size is 0, the function will generate EC keypair and update context, and fill PublicKeySize with non-zero keysize to indicate success.
>
> (CryptEc.c  L492)
>    if ((PublicKey == NULL) && (*PublicKeySize != 0)) {
>      return FALSE;
>    }

Thanks to make me know :)

IIUC, That special case could be used with EcGetPubKey.

>
> I recommend the below changes:
>
>    HalfSize = (EC_GROUP_get_degree (Group) + 7) / 8;
>
> +  if ((PublicKey != NULL) && (*PublicKeySize < HalfSize * 2)) {
> +    *PublicKeySize = HalfSize * 2;
> +    return FALSE;
> +  }
>    // Assume RAND_seed was called
>    if (EC_KEY_generate_key (EcKey) != 1) {
>      return FALSE;
>    }
>
> -  if (*PublicKeySize < HalfSize * 2) {
> + // If PublicKey is NULL and PublicKeySize is 0, return TRUE and fill PublicKeySize with correct Key size.
> + if (*PublicKeySize == 0) {
>      *PublicKeySize = HalfSize * 2;
> -   return FALSE;
> +   return TRUE;
>    }

Look good to me But it would be better to set key size above of If clause.

I'll send the patch again :)


Many thanks.

--------

Sincerely,

Levi.


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