using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        var plainValue = "something to encode";

        Console.WriteLine($"Unencoded value: {plainValue}\r\n");

        var encodedValue = Convert.ToBase64String(Encoding.ASCII.GetBytes(plainValue));

        Console.WriteLine($"Encoded value: {encodedValue}\r\n");

​

        var originalValue = Encoding.UTF8.GetString(Convert.FromBase64String(encodedValue));

        Console.WriteLine($"Original unencoded value: {originalValue}");

    }

}