keygen.java

一个简单的RSA 实现程序

package SimpleRSA;

import java.io.IOException;
import java.math.BigInteger;
import java.util.Random;

public class KeyGen 
{
	private BigInteger getPQ()
	{
		BigInteger temp;
		temp = BigInteger.probablePrime(5,rnd);
		return temp;
	}
	
	private BigInteger getN()
	{
		BigInteger temp;
		temp = p.multiply(q);
		return temp;
	}
	
	private BigInteger getE()
	{
		BigInteger temp = new BigInteger(7,rnd);
		return temp;
	}
	
	private BigInteger getD()
	{
		BigInteger p_1,q_1,n_1;
		p_1 = p.subtract(BigInteger.valueOf(1));
		q_1 = q.subtract(BigInteger.valueOf(1));
		n_1 = p_1.multiply(q_1);
		try
		{
			d = e.modInverse(n_1);
			flag = true;
		}
		catch(Exception e1)
		{
			//System.out.println("No inverse");
		}
		return d;
	}
	
	static void keygen(String args) throws IOException
	{
		KeyGen key= new KeyGen();
		int public_key[] = new int [2];
		int private_key[] = new int [3];
		while(flag == false)
		{
			p = key.getPQ();
			q = key.getPQ();
			n = key.getN();
			e = key.getE();
			d = key.getD();
			if(e.equals(d)) flag =false;
		}flag = false;
		
		public_key[0]  = n.intValue();
		public_key[1]  = e.intValue();
		String destination = args + "public_keys.txt";
		Input_Output.Output_Key(destination, public_key);
		
		private_key[0] = n.intValue();
		private_key[1] = e.intValue();
		private_key[2] = d.intValue();
		destination = args + "private_keys.txt";
		Input_Output.Output_Key(destination, private_key);
		
		System.out.println("The n is: "+ n);
		System.out.println("The public key is: "+ e);
		System.out.println("The private key is: "+ d);
		

	}
	
	private Random rnd = new Random();
	private static BigInteger p,q,n,e,d;
	private static boolean flag = false;
}