public function sha256SigOk(string $qs_url_uri, string $key = '', string $sig_var = ''): bool
    {
        $sig_var = $sig_var ?: $this::DEFAULT_SIG_VAR;
        $args    = $this->parse($qs_url_uri);
        $sig     = $this->sha256Sig($qs_url_uri, $key, $sig_var);

        return !empty($args[$sig_var]) && $args[$sig_var] === $sig;
    }