Java中的Diffie-Hellman密钥交换

Question

我正在开发一个Java的个人项目,涉及通过不安全的渠道发送敏感数据.我需要知道如何使用其库在Java中实现Diffie Hellman密钥交换(DHKE).我知道关于它的所有加密理论所以不需要详细说明,我只需要一个非常基本的实现,所以我可以让2个程序共享一个密钥.我从java2s.com获得了示例,但它并不完整:

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;

import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.DHPublicKeySpec;

public class Main {
  public final static int pValue = 47;

  public final static int gValue = 71;

  public final static int XaValue = 9;

  public final static int XbValue = 14;

  public static void main(String[] args) throws Exception {
    BigInteger p = new BigInteger(Integer.toString(pValue));
    BigInteger g = new BigInteger(Integer.toString(gValue));
    BigInteger Xa = new BigInteger(Integer.toString(XaValue));
    BigInteger Xb = new BigInteger(Integer.toString(XbValue));

    int bitLength = 512; // 512 bits
    SecureRandom rnd = new SecureRandom();
    p = BigInteger.probablePrime(bitLength, rnd);
    g = BigInteger.probablePrime(bitLength, rnd);

    createSpecificKey(p, g);
  }

  public static void createSpecificKey(BigInteger p, BigInteger g) throws Exception {
    KeyPairGenerator kpg = KeyPairGenerator.getInstance("DiffieHellman");

    DHParameterSpec param = new DHParameterSpec(p, g);
    kpg.initialize(param);
    KeyPair kp = kpg.generateKeyPair();

    KeyFactory kfactory = KeyFactory.getInstance("DiffieHellman");

    DHPublicKeySpec kspec = (DHPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
        DHPublicKeySpec.class);
  }
}

我怎么继续这个？任何人都可以帮我完成剩余的代码吗？

Answer 1

什么Oracle官方文档？他们在那里显示代码中的DH密钥交换.

Answer 2

以下代码使用 Elliptic Curve Diffie-Hellman 生成并共享 128 位密钥和 AES 进行加密。

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import java.io.IOException;
import java.security.*;

public class AESSecurityCap {

    private PublicKey publickey;
    KeyAgreement keyAgreement;
    byte[] sharedsecret;

    String ALGO = "AES";

    AESSecurityCap() {
        makeKeyExchangeParams();
    }

    private void makeKeyExchangeParams() {
        KeyPairGenerator kpg = null;
        try {
            kpg = KeyPairGenerator.getInstance("EC");
            kpg.initialize(128);
            KeyPair kp = kpg.generateKeyPair();
            publickey = kp.getPublic();
            keyAgreement = KeyAgreement.getInstance("ECDH");
            keyAgreement.init(kp.getPrivate());

        } catch (NoSuchAlgorithmException | InvalidKeyException e) {
            e.printStackTrace();
        }
    }

    public void setReceiverPublicKey(PublicKey publickey) {
        try {
            keyAgreement.doPhase(publickey, true);
            sharedsecret = keyAgreement.generateSecret();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
    }

    public String encrypt(String msg) {
        try {
            Key key = generateKey();
            Cipher c = Cipher.getInstance(ALGO);
            c.init(Cipher.ENCRYPT_MODE, key);
            byte[] encVal = c.doFinal(msg.getBytes());
            return new BASE64Encoder().encode(encVal);
        } catch (BadPaddingException | InvalidKeyException | NoSuchPaddingException | IllegalBlockSizeException | NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return msg;
    }

    public String decrypt(String encryptedData) {
        try {
            Key key = generateKey();
            Cipher c = Cipher.getInstance(ALGO);
            c.init(Cipher.DECRYPT_MODE, key);
            byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedData);
            byte[] decValue = c.doFinal(decordedValue);
            return new String(decValue);
        } catch (BadPaddingException | InvalidKeyException | NoSuchPaddingException | IllegalBlockSizeException | NoSuchAlgorithmException | IOException e) {
            e.printStackTrace();
        }
        return encryptedData;
    }

    public PublicKey getPublickey() {
        return publickey;
    }

    protected Key generateKey() {
        return new SecretKeySpec(sharedsecret, ALGO);
    }
}

扩展您自己的类以添加 AES 加密功能

public class Node extends AESSecurityCap {

//your class

}

最后，使用加密的方法

public class Main {

    public static void main(String[] args) throws IOException {
        Node server = new Node();
        Node client = new Node();

        server.setReceiverPublicKey(client.getPublickey());

        client.setReceiverPublicKey(server.getPublickey());

        String data = "hello";

        String enc = server.encrypt(data);

        System.out.println("hello is coverted to "+enc);

        System.out.println(enc+" is converted to "+client.decrypt(enc));

    }
}

输出：

hello is coverted to OugbNvUuylvAr9mKv//nLA==
OugbNvUuylvAr9mKv//nLA== is converted to hello

Process finished with exit code 0