using System;

public class Program

{

    //Ref - https://github.com/base64decode/examples/blob/master/base64decode.cs

    public static void Main()

    {

        string base64Encoded = "YmFzZTY0IGVuY29kZWQgc3RyaW5n"; //Value is 'base64 encoded string'

        string base64Decoded;

        byte[] data = System.Convert.FromBase64String(base64Encoded);

        base64Decoded = System.Text.ASCIIEncoding.ASCII.GetString(data);

        Console.WriteLine("Decoded String = "+ base64Decoded);

        //string base64str = System.Convert.ToBase64String(data);//Converting Back text to base 64 and trying to equate with original base 64 string        

        //Console.WriteLine(base64Encoded == base64str);

    }

    /*

    public static string Base64Encode(string plainText) {

  var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);

  return System.Convert.ToBase64String(plainTextBytes);

}

Decode

public static string Base64Decode(string base64EncodedData) {

  var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);

  return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);

}

    */

}