O2Jam e-Games auth token encode/decode

egameencrypt.cs

using System;
using System.Text;

public class Program
{
    public static void Main(string[] args)
    {
        // Encoding: UTF16-BE (BigEndianUnicode in C#)
        string encoded = "ADAAOQBEADUAQgBBADcAQwAtADUARQAyAEEALQA0ADYANQBBAC0AOQA4AEUARAAtADgAMgBDADYAOAA1AEEARgAxAEYAMQA4";
        string decoded = "09D5BA7C-5E2A-465A-98ED-82C685AF1F18";
        
        // Decode
        var decodedPayload = Convert.FromBase64String(encoded);
        Console.WriteLine(Encoding.BigEndianUnicode.GetString(decodedPayload)); // == decoded
        
        // Encode
        var rawPayload = Encoding.BigEndianUnicode.GetBytes(decoded);
        Console.WriteLine(Convert.ToBase64String(rawPayload)); // == encoded
    }
}