加密类+序列化类

我试图在序列化类之前加密它。我发现的唯一方法是加密它并返回字符串或流，是否有可能返回原始类?

public static Options Encrypt(Options Settings)
{
    Options sk = null;
    try
    {
        using (var stream = new MemoryStream())
        {
            RuntimeTypeModel.Default.Serialize(stream, Settings);
            byte[] data = encryptWithPadding(stream.ToArray(), 0);
            String base64EncryptedString = Convert.ToBase64String(data);
            // needs to return an option instance
        }
    }
    catch (Exception e)
    {
         Global.LogError("Serialization failed", e);
    }

    return sk;
}