How to serialize an object in C# and prevent tampering?

Question

I have a C# class as follows:

public class TestObj
{
    private int intval;
    private string stringval;
    private int[] intarray;
    private string[] stringarray;

    //... public properties not shown here
}

I would like to serialize an instance of this class into a string.

In addition:

I will be appending this string as a QueryString param to a URL. So I would like to take some effort to ensure that the string cannot be tampered with easily.

Also, I would like the serialization method to be efficient so the size of the string is minmal.

Any suggestions of specific .NET Framework classes/methods I should use?

Answer 1

Sign the stream and add the signature to your query. Use a HMAC signing algorithm, like HMACSHA1. You will need to have a secret between your client and your server to sign and validate the signature.