using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using System;

namespace CryptoTest
{
    class Program
    {

        static void Main(string[] args)
        {
            Console.WriteLine("Calculating a 1024-bits primenumber for key 1");

            BigInteger prime = GenPrime2(1024);
            Console.WriteLine("Found a prime: " + prime.ToString());

            Console.WriteLine("Running calculations to make sure this is a prime...");
            bool probablePrime = prime.IsProbablePrime(100);

            Console.WriteLine("Calculation completed. Is prime: " + probablePrime.ToString());

            if (probablePrime)
            {
                Console.WriteLine("Calculating a 1024-bits primenumber for key 2");

                BigInteger prime2 = GenPrime2(1024);
                Console.WriteLine("Found a prime: " + prime.ToString());

                Console.WriteLine("Running calculations to make sure this is a prime...");
                probablePrime = prime2.IsProbablePrime(100);

                Console.WriteLine("Calculation completed. Is prime: " + probablePrime.ToString());

                if (probablePrime)
                {
                    Console.WriteLine("Both keys are prime numbers, concentrating them to make a 2048-bit key");
                    BigInteger key = new BigInteger(prime.ToString() + prime2.ToString());

                    Console.WriteLine("Key forged: " + key.ToString());
                } else {
                    Console.WriteLine("Could not find prime for key 2");
                }
            } else {
                Console.WriteLine("Could not find a prime for key 1");
            }


            // Just read to make sure console doesn't close
            Console.Read();
        }

        static public BigInteger GenPrime2(int bits)
        {
            SecureRandom ran = new SecureRandom();

            BigInteger c = new BigInteger(bits, ran);

            for (; ; )
            {
                if (c.IsProbablePrime(1) == true) break;

                c = c.Subtract(new BigInteger("1"));
            }
            return (c);
        }
    }
}