using System;

public class Program

{

    public static void Main()

    {

​

      var fromText = System.Guid.NewGuid().ToString();

      var fromByte = System.Text.Encoding.UTF8.GetBytes(fromText);  

      var mySHA256 = System.Security.Cryptography.SHA256Managed.Create();    

      var toString= Convert.ToBase64String(mySHA256.ComputeHash(fromByte));

      Console.WriteLine(fromText);

      Console.WriteLine(toString);

    }

}