public function decryptBinary(string $value, string $key): string
    {
        $iv = substr($value, 0, $this->ivLength);
        $encrypted = substr($value, $this->ivLength);
        $key = $this->hashKey($key);
        $opts = OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING;
        $ret = openssl_decrypt($encrypted, $this->cipher, $key, $opts, $iv);
        if ($ret === false) {
            throw new \Exception("decryption failed; ".openssl_error_string());
        }
        return $ret;
    }