Thread: Cipher Client/Server Encryption/Decryption Program - Please Help

import java.io.*;
import java.net.*;
import java.security.*;
import javax.crypto.*;
 
public class CipherClient
{
	public static void main(String[] args) throws Exception 
	{
		// -Generate a DES key.
		Key key1;
		KeyGenerator kg = KeyGenerator.getInstance("DES");
		kg.init(new SecureRandom());
		key1 = kg.generateKey();
 
                String message = "The quick brown fox jumps over the lazy dog.";
		String host = "127.0.0.1";
		int port = 7999;
		Socket s = new Socket(host, port);            
 
                // -Store it in a file.
		ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("Keyfile3.txt"));
		out.writeObject(key1);
                out.close();
 
		// -Use the key to encrypt the message above and send it over socket s to the server.
		Cipher cipher = Cipher.getInstance("DES");
		cipher.init(Cipher.ENCRYPT_MODE, key1);
		CipherOutputStream cipherout = new CipherOutputStream(s.getOutputStream(),cipher);
                cipherout.write(message.getBytes());
 
	}
}

import java.io.*;
import java.net.*;
import java.security.*;
import javax.crypto.*;
 
public class CipherServer
{
	public static void main(String[] args) throws Exception 
	{
		int port = 7999;
		ServerSocket server = new ServerSocket(port);
		Socket s = server.accept();
 
		// -Read the key from the file generated by the client.
		ObjectInputStream in = new ObjectInputStream(new FileInputStream("Keyfile3.txt"));
		Key key1 = (Key)in.readObject();
 
		// -Use the key to decrypt the incoming message from socket s.	
		Cipher cipher = Cipher.getInstance("DES");
		cipher.init(Cipher.DECRYPT_MODE, key1);
		CipherInputStream cipherIn = new CipherInputStream(s.getInputStream(), cipher);
 
		// -Print out the decrypt String to see if it matches the original message.
		FileOutputStream fos = new FileOutputStream("output3.txt");
 
		byte[] buffer = new byte[1024];
                int length = cipherIn.read(buffer);
                fos.write(buffer, 0, length);
                fos.flush();
                fos.close();
                cipherIn.close();
	}
}

Errors that I'm getting on CipherClient:
run:
Exception in thread "main" java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.pee kByte(ObjectInputStream.java:2577)
at java.io.ObjectInputStream.readObject0(ObjectInputS tream.java:1315)
at java.io.ObjectInputStream.readObject(ObjectInputSt ream.java:369)
at CipherServer.main(CipherServer.java:16)
Java Result: 1
BUILD SUCCESSFUL (total time: 8 seconds)


Errors that I get when running on CipherServer:
run:
Exception in thread "main" java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutp utStream.java:109)
at java.net.SocketOutputStream.write(SocketOutputStre am.java:141)
at javax.crypto.CipherOutputStream.write(CipherOutput Stream.java:157)
at javax.crypto.CipherOutputStream.write(CipherOutput Stream.java:141)
at CipherClient.main(CipherClient.java:30)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

My intent is for the key to be read from:

out.writeObject(key1);

after the key has been made and stored.

Keyfile3.txt

Server executed first, and client afterwards.

IC - didn't think of that till just now.

I have the client looking at the server for the socket, so if I reverse it will error out too.

Any recommendations?

With "KeyFile3.ser"? I sorry to bother you, but I'm lost.

I do want the client to write the key before server reading it.

Client - writes key on server to keyfile.txt ==> uses keyfile.txt from server to encrypt message string ==> creating cipherstream
Server - accept socket ==> accept keyfile.txt ==> uses keyfile.txt from server to decrypt message string ==> write output from original string

I'm probably thinking about this all wrong, but that's my intent of the program.

Thank you!