import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
import org.omg.CORBA.portable.OutputStream;

public class Client {

	  public static final String PUBLIC_KEY_FILE = "C:\\Users\\Neo\\Desktop\\RSA\\klucz.key";

	  public static byte[] encrypt(String text, PublicKey key) {
		    byte[] cipherText = null;
		    try {

		      final Cipher cipher = Cipher.getInstance("RSA");

		      cipher.init(Cipher.ENCRYPT_MODE, key);
		      cipherText = cipher.doFinal(text.getBytes());
		    } catch (Exception e) {
		      e.printStackTrace();
		    }
		    return cipherText;
		  }

	public static void main(String[] args) throws IOException, ClassNotFoundException {
				try(
				  ReadableByteChannel in=Channels.newChannel(
				    new URL("http://145.239.90.206/public.key").openStream());
				  FileChannel out=new FileOutputStream("C:\\Users\\Neo\\Desktop\\eklucz.key").getChannel() )
				{

				  out.transferFrom(in, 0, Long.MAX_VALUE);
				}
				System.out.println("Pobralem klucz publiczny wygenerowany przez serwer (145.239.90.206/klucz.key)");

		    try
		    {
		      final String originalText = "Tajna wiadomosc BT";
	          ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("C:\\Users\\Neo\\Desktop\\klucz.key"));
	         final PublicKey publicKey = (PublicKey) 	inputStream.readObject();
	         final byte[] cipherText = encrypt(originalText, publicKey);
	         	 String zaszyfrowana_rsa = new Base64().encodeToString(cipherText);
		         System.out.println("Zaszyfrowana wiadomosc: " + zaszyfrowana_rsa);
		         System.out.println("Wysylam do serwera.");
		         Socket clientSocket = new Socket("145.239.90.206", 8888);

		         DataOutputStream dOut = new DataOutputStream(clientSocket.getOutputStream()); // wysylamam do serwera

		         dOut.writeInt(cipherText.length);
		         dOut.write(cipherText);
		         clientSocket.close();

		    } catch (Exception e) {
		        e.printStackTrace();
		    }
		  }

	    }