Encrypting additional parameters should using AES-256-CBC

[epubreader]

// Encrypting additional parameters using AES-256-CBC (for >= PHP 7)
$iv = substr(hash('sha256', $key), 0, 16);
$m_params = urlencode(base64_encode(openssl_encrypt(json_encode($arParams),'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv)));