Re: [RFC 5/8] cert-crypto: refactor l_cert_pkcs5_pbkdf2

Hi James,

On 11/18/22 15:16, James Prestwood wrote:
> This makes the actual algorithm common to prepare for adding a
> new variant which uses a key ID rather than password.
> ---
>   ell/cert-crypto.c | 67 +++++++++++++++++++++++++++++------------------
>   1 file changed, 41 insertions(+), 26 deletions(-)
> 
> diff --git a/ell/cert-crypto.c b/ell/cert-crypto.c
> index e6e8876..bf748b0 100644
> --- a/ell/cert-crypto.c
> +++ b/ell/cert-crypto.c
> @@ -103,44 +103,34 @@ LIB_EXPORT bool l_cert_pkcs5_pbkdf1(enum l_checksum_type type,
>   	return !iter_count;
>   }
>   
> -/* RFC8018 section 5.2 */
> -LIB_EXPORT bool l_cert_pkcs5_pbkdf2(enum l_checksum_type type,
> -					const char *password,
> -					const uint8_t *salt, size_t salt_len,
> -					unsigned int iter_count,
> -					uint8_t *out_dk, size_t dk_len)
> +static size_t cert_checksum_to_length(enum l_checksum_type type)

We already have l_checksum_digest_length().  Should we use that?

>   {
> -	size_t h_len;
> -	struct l_checksum *checksum;
> -	unsigned int i;
> -
>   	switch (type) {
>   	case L_CHECKSUM_SHA1:
> -		h_len = 20;
> -		break;
> +		return 20;
>   	case L_CHECKSUM_SHA224:
> -		h_len = 28;
> -		break;
> +		return 28;
>   	case L_CHECKSUM_SHA256:
> -		h_len = 32;
> -		break;
> +		return 32;
>   	case L_CHECKSUM_SHA384:
> -		h_len = 48;
> -		break;
> +		return 48;
>   	case L_CHECKSUM_SHA512:
> -		h_len = 64;
> -		break;
> +		return 64;
>   	case L_CHECKSUM_NONE:
>   	case L_CHECKSUM_MD4:
>   	case L_CHECKSUM_MD5:
> -		return false;
> +		return 0;
>   	default:
> -		return false;
> +		return 0;
>   	}
> +}
>   
> -	checksum = l_checksum_new_hmac(type, password, strlen(password));
> -	if (!checksum)
> -		return false;
> +static bool cert_pkcs5_pbkdf2(struct l_checksum *checksum, const uint8_t *salt,
> +				size_t salt_len, size_t h_len,
> +				unsigned int iter_count, uint8_t *out_dk,
> +				size_t dk_len)
> +{
> +	unsigned int i;
>   
>   	for (i = 1; dk_len; i++) {
>   		unsigned int j, k;

Regards,
-Denis