java实现服务端客户端使用数字信封进行加密通信代码

以下是Java实现服务端客户端使用数字信封进行加密通信的代码：

服务端代码：

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

public class Server {
    public static void main(String[] args) throws Exception {
        int port = 12345;

        // 生成RSA密钥对
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        PrivateKey privateKey = keyPair.getPrivate();
        PublicKey publicKey = keyPair.getPublic();

        // 等待客户端连接
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("等待客户端连接...");
        Socket socket = serverSocket.accept();
        System.out.println("客户端已连接");

        // 发送公钥给客户端
        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
        out.writeObject(publicKey);

        // 接收客户端发来的数字信封
        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
        SealedObject sealedObject = (SealedObject)in.readObject();

        // 解密数字信封
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.UNWRAP_MODE, privateKey);
        Key sessionKey = (Key)cipher.unwrap(sealedObject.getEncryptedKey(), "AES", Cipher.SECRET_KEY);

        // 使用会话密钥进行加密通信
        cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, sessionKey, new IvParameterSpec(new byte[16]));
        DataInputStream dis = new DataInputStream(socket.getInputStream());
        while (true) {
            String message = dis.readUTF();
            byte[] encryptedMessage = Base64.getDecoder().decode(message);
            byte[] decryptedMessage = cipher.doFinal(encryptedMessage);
            System.out.println("收到消息：" + new String(decryptedMessage));
        }
    }
}

客户端代码：

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

public class Client {
    public static void main(String[] args) throws Exception {
        String host = "localhost";
        int port = 12345;

        // 连接服务端
        Socket socket = new Socket(host, port);
        System.out.println("已连接服务器");

        // 接收服务端公钥
        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
        PublicKey publicKey = (PublicKey)in.readObject();

        // 使用公钥加密会话密钥，并将数字信封发送给服务端
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.WRAP_MODE, publicKey);
        KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        keyGen.init(128);
        Key sessionKey = keyGen.generateKey();
        SealedObject sealedObject = new SealedObject(sessionKey, cipher);

        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
        out.writeObject(sealedObject);

        // 使用会话密钥进行加密通信
        cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, sessionKey, new IvParameterSpec(new byte[16]));
        DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String message = br.readLine();
            byte[] encryptedMessage = cipher.doFinal(message.getBytes());
            String base64EncodedMessage = Base64.getEncoder().encodeToString(encryptedMessage);
            dos.writeUTF(base64EncodedMessage);
            dos.flush();
        }
    }
}

注意：以上代码仅供参考，实际应用中需要进行适当的安全性改进，比如使用更长的密钥、使用更安全的加密算法等。