package clientcert;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.net.Socket;
import java.net.UnknownHostException;
import java.security.cert.CertificateExpiredException;
import java.security.cert.CertificateNotYetValidException;
import java.security.cert.X509Certificate;
import java.util.logging.Level;
import java.util.logging.Logger;
import sun.security.tools.keytool.CertAndKeyGen;
import sun.security.x509.X500Name;

public class ClientCert {

	public static void main(String args[]) {
		String host = "127.0.0.1";
		int port = 8081;
		new ClientCert(host, port);
	}

	public ClientCert(String host, int port) {
		try {
                        boolean firstTime=true;
			String serverHostname = new String("127.0.0.1");

			System.out.println("Connecting to host " + serverHostname + " on port " + port + ".");

			Socket echoSocket = null;
			PrintWriter out = null;
			BufferedReader in = null;



			try {
				echoSocket = new Socket(serverHostname, 8081);
				out = new PrintWriter(echoSocket.getOutputStream(), true);
				in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));


			} catch (UnknownHostException e) {
				System.err.println("Unknown host: " + serverHostname);
				System.exit(1);
			} catch (IOException e) {
				System.err.println("Unable to get streams from server");
				System.exit(1);
			}

			/** {@link UnknownHost} object used to read from console */
                        OutputStreamWriter os = new OutputStreamWriter(echoSocket.getOutputStream());
                        PrintWriter outS = new PrintWriter(os);

                        DataInputStream inS = new DataInputStream(System.in);

			BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

                        // Certificat PART -------------------------------------
                        // Sending Certificate to the server
                        new ObjectOutputStream(echoSocket.getOutputStream()).writeObject(createCertificate("Client"));
                        // ~~

                        // Reading Certificate from Client
                        X509Certificate[] recievedCert=new X509Certificate[1];
                        recievedCert[0] =  (X509Certificate) new ObjectInputStream(echoSocket.getInputStream()).readObject();
                        System.out.println("Certificate Recieved from : "+recievedCert[0].getIssuerDN());
                        // ~~
                        recievedCert[0].checkValidity();
                        // -----------------------------------------------------


                        //Diffie Hellman Sessions keys
                        BigInteger phi = new BigInteger(in.readLine());
                        System.out.println("Received phi = " + phi);

                        BigInteger e = new BigInteger(in.readLine());
                        System.out.println("Received e = " + e);

                        BigInteger n = new BigInteger(in.readLine());
                        System.out.println("Received n = " + n);
                        // -----------------------------------------------------
                       while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && e.compareTo(phi) < 0) {

                         e.add(BigInteger.ONE);

                            }

                            BigInteger d = e.modInverse(phi);
                            System.out.println("Self-Generated d = " + d);

                            System.out.println("Client is Ready");
			 while (true) {

				System.out.print("client: ");
				String userInput = inS.readLine();

                                byte[] encrypted = (new BigInteger(userInput.getBytes())).modPow(e, n).toByteArray();
                                //System.out.println("Encrypted String in Bytes: " + bytesToString(encrypted));

                                outS.println(new BigInteger(encrypted));
                                os.flush();

				/** Exit on 'q' char sent */
				if ("q".equals(userInput)) {
					break;
				}


			}

			/** Closing all the resources */
			out.close();
			in.close();
			stdIn.close();
			echoSocket.close();
		}
                catch (ClassNotFoundException ex) {
                Logger.getLogger(ClientCert.class.getName()).log(Level.SEVERE, null, ex);
            } catch (CertificateExpiredException ex) {
                Logger.getLogger(ClientCert.class.getName()).log(Level.SEVERE, null, ex);
            } catch (CertificateNotYetValidException ex) {
                Logger.getLogger(ClientCert.class.getName()).log(Level.SEVERE, null, ex);
            }catch (Exception e) {
			e.printStackTrace();
		}
	}

       public X509Certificate createCertificate(String IssuerName)
{
try{
            CertAndKeyGen keyGen=new CertAndKeyGen("RSA","SHA1WithRSA",null);
            keyGen.generate(1024);


            //Generate self signed certificate
            X509Certificate[] chain=new X509Certificate[1];
            chain[0]=keyGen.getSelfCertificate(new X500Name("CN="+IssuerName), (long)365*24*3600);
            //System.out.println("Certificate : "+chain[0].toString());
            return chain[0];
        }catch(Exception ex){
            ex.printStackTrace();
        }
            return null;
}

    private String bytesToString(byte[] encrypted) {
        String test = "";

        for (byte b : encrypted) {

            test += Byte.toString(b);

        }

        return test;

    }

}