java - 在 Java 中生成 DES key 并通过套接字传递它

Question

有人可以帮我解决我非常简单的程序中的问题吗？

在服务器上输出消息时，我希望看到通过网络发送的相同消息，但我没有收到。

这是我为客户提供的代码:

package encryption;

import java.io.*;
import java.net.*;
import java.security.*;
import java.util.*;
import javax.crypto.*;

public class CipherClient
{
    public static void main(String[] args) throws Exception 
    {
        String message = "The quick brown fox jumps over the lazy dog.";
        String host = "localhost";
        int port = 7999;
        Socket s = new Socket(host, port);

        // -Generate a DES key.
        KeyGenerator generator = KeyGenerator.getInstance("DES");
        generator.init(new SecureRandom());
        Key key = generator.generateKey();

        // -Store it in a file.
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("KeyFile.xx"));
        out.writeObject(key);
        out.close();

        // -Use the key to encrypt the message above and send it over socket s to the server.   
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        CipherOutputStream cipherOut = new CipherOutputStream(s.getOutputStream(), cipher);
        System.out.println(message.getBytes().length);
        cipherOut.write(message.getBytes());
    }
}

这是我的服务器代码:

package encryption;

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("KeyFile.xx"));
        Key key = (Key)in.readObject();
        System.out.println(key.getClass().getName());
        in.close();

        // -Use the key to decrypt the incoming message from socket s.      
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);
        CipherInputStream cipherIn = new CipherInputStream(s.getInputStream(), cipher);
        byte[] stringInBytes = new byte[44];
        cipherIn.read(stringInBytes);
        String string = new String(stringInBytes);

        // -Print out the decrypt String to see if it matches the orignal message.
        System.out.println(string);
    }
}

服务器端控制台输出:

javax.crypto.spec.SecretKeySpec
}#ùÂ?°ô0íÿ| r|XÌ\?ñwŽ³{Í@nŠ?

客户端控制台输出:

44

这是我为客户提供的新代码:

package encryption;

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.
        KeyGenerator generator = KeyGenerator.getInstance("DES");
        generator.init(new SecureRandom());
        Key key = generator.generateKey();

        // -Store it in a file.
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("KeyFile.xx"));
        out.writeObject(key);
        out.close();

        // -Connect to a server.
        String message = "The quick brown fox jumps over the lazy dog.";
        String host = "localhost";
        int port = 7999;
        Socket s = new Socket(host, port);

        // -Use the key to encrypt the message above and send it over socket s to the server.   
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] encVal = cipher.doFinal(message.getBytes());
        DataOutputStream dOut = new DataOutputStream(s.getOutputStream());
        dOut.writeInt(encVal.length); // write length of the message
        dOut.write(encVal);           // write the message
    }
}

这是我的新服务器代码:

package encryption;

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("KeyFile.xx"));
        Key key = (Key)in.readObject();
        in.close();

        // -Use the key to decrypt the incoming message from socket s.    
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);

        DataInputStream dIn = new DataInputStream(s.getInputStream());
        int length = dIn.readInt();                    // read length of incoming message
        if(length>0) 
        {
            byte[] messageInBytes = new byte[length];
            dIn.readFully(messageInBytes, 0, messageInBytes.length); // read the message

            // -Print out the decrypt String to see if it matches the orignal message.
            System.out.println(new String(cipher.doFinal(messageInBytes)));
        }
    }
}

这是我在服务器端遇到的错误:

Exception in thread "main" java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read(Unknown Source)
    at java.net.SocketInputStream.read(Unknown Source)
    at java.net.SocketInputStream.read(Unknown Source)
    at java.io.DataInputStream.readInt(Unknown Source)
    at encryption.CipherServer.main(CipherServer.java:26)

客户端没有错误。

Answer 1

我认为您的客户端和服务器之间存在“竞赛”，以写入和读取您的 key 文件。至少当我运行你的代码时它对我有用。

在创建套接字之前尝试将 key 生成和写入 key 文件。这样，当您的客户端创建其套接字时，服务器会接受它，并且当它访问该文件时，它确实会获得一个有效的文件。

它对我有用，除了写入文件位之外，与您的代码几乎没有任何区别。

客户端:

public class CipherClient
{
    public static void main(String[] args) throws Exception 
    {
        // -Generate a DES key.
        KeyGenerator generator = KeyGenerator.getInstance("DES");
        generator.init(new SecureRandom());
        Key key = generator.generateKey();

        // -Store it in a file.
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("KeyFile.xx"));
        out.writeObject(key);
        out.close();

        String message = "The quick brown fox jumps over the lazy dog.";
        System.out.println("Message converted from Bytes = " + new String(message.getBytes()));
        System.out.println("Length = " + message.getBytes().length);

        String host = "localhost";
        int port = 7999;
        Socket s = new Socket(host, port);

        // -Use the key to encrypt the message above and send it over socket s to the server.   
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        CipherOutputStream cipherOut = new CipherOutputStream(s.getOutputStream(), cipher);
        cipherOut.write(message.getBytes());
        cipherOut.close();
        s.close();
    }
}

和服务器:

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("KeyFile.xx"));
        Key key = (Key)in.readObject();
        in.close();

        // -Use the key to decrypt the incoming message from socket s.      
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);
        CipherInputStream cipherIn = new CipherInputStream(s.getInputStream(), cipher);

        byte[] array = new byte[44];
        cipherIn.read(array);
        cipherIn.close();
        s.close();

        String message = new String(array);
        System.out.println(message);
    }
}