Generating Prime Numbers

Many public key algorithms depend on prime number, which are difficult to factorize when multiplied together. This program creates the ones from 1 to :
Primes
The following is the code:
using System;
using System.Data;
using System.Configuration;

using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
using System.Security.Cryptography;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Drawing;
using System.Net;
using System.Threading;

public partial class _Default5 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }

    protected void Button3_Click(object sender, EventArgs e)
    {
        findprimes = true;
       goPrimes();

  
    }
    string primeList = "";

    static ulong RecursiveModulo(ulong uBase, ulong uPower, ulong uDivisor)
    {
        ulong uAux;

        if (uPower == 0) return 1;

        //a^2c mod n = (ac mod n)2 mod n
        else if (uPower % 2 == 0)
        {
            uAux = RecursiveModulo(uBase, uPower / 2, uDivisor);
            return (uAux * uAux) % uDivisor;
        }
        //ac+1 mod n = (ac mod n) · a mod n
        else return (RecursiveModulo(uBase, uPower - 1, uDivisor) * uBase) % uDivisor;
    }
        

    public static bool TestPrime(ulong uNumber, uint uIterations)
    {
        Random Rnd = new Random();
        ulong uAux;
        for (ulong i = 0; i < uIterations; ++i)
        {
            uAux = (ulong)(Rnd.Next()) % uNumber;
            if (uAux == 0) uAux = uNumber - 1;
            if (RecursiveModulo(uAux, uNumber - 1, uNumber) != 1)
            {
                return false;
            }
        }
        return true;

    }


    bool findprimes = false;
    public void goPrimes()
    {
        int j = 0;
  //      for (uint i = 2; i < Math.Pow(2, 32); i++)
        for (uint i = 2; i < 5000; i++)
        {
            if (i == 2) tbMessage.Text= "\r\nPrime numbers:\r\n";
            if (findprimes == false) { return; }
            if (TestPrime(i, 2) == true && findprimes == true)
            {
                j++;
                if (j % 10 == 0)
                {

                    tbMessage.Text+= primeList + "\r\n";
                    primeList = "";
                }
                else primeList += Convert.ToString(i) + "\t";



            }
            System.Threading.Thread.Sleep(2);
        }
    }

}