非对称加密算法DH

package com.imooc.security.dh;

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;
import java.util.Objects;

import javax.crypto.Cipher;
import javax.crypto.KeyAgreement;
import javax.crypto.SecretKey;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;

import org.apache.commons.codec.binary.Base64;

/**
 * 非对称加密算法
 * @author Bingo_Ge
 *
 */
public class ImoocDH {
	private static String src = "imooc security dh";
	
	public static void main(String[] args) {
		jdkDH();
	}
	
	//比较复杂
	public static void jdkDH() {
		try {
			// 1.初始化发送方（甲方）密钥（公开自己的公钥，保留私钥）
			KeyPairGenerator senderKeyPairGenerator = KeyPairGenerator.getInstance("DH"); //使用DH非对称加密方式
			senderKeyPairGenerator.initialize(512);
			KeyPair senderKeyPair = senderKeyPairGenerator.generateKeyPair();  //生成发送发的密钥对
			byte[] senderPublicKeyEnc = senderKeyPair.getPublic().getEncoded(); //发送方（甲方）公开的密钥
			
			
			// 2.初始化接收方（乙方）密钥（同样也是公开自己的公钥，保留私钥）
			/*
			 * 发送者公钥通过X509EncodedKeySpec类生成接收者（乙方）公钥，再由公钥类得到**（DH）ParameterSpec，然后生成KeyPair得到接收者私钥，最后通过生成的公钥、私钥构建自己的密钥
			 * 发送者的公钥并不是刚开始生成的公钥，同样的是由接收者的KeyPair类的getPublic().getEncoded()传入X509EncodedKeySpec类生成
			 */
			KeyFactory receiverKeyFactory = KeyFactory.getInstance("DH"); //同样也是DH
			X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(senderPublicKeyEnc); //传入发送方公开的密钥
			PublicKey receiverPublicKey = receiverKeyFactory.generatePublic(x509EncodedKeySpec); //生成自己的公钥
			DHParameterSpec dhParameterSpec = ((DHPublicKey)receiverPublicKey).getParams(); //需要强转成DHPublicKey
			KeyPairGenerator receiverKeyPairGenerator = KeyPairGenerator.getInstance("DH"); //同样要使用DH非对称加密方式
			receiverKeyPairGenerator.initialize(dhParameterSpec); //初始化方式为根据x509EncodedKeySpec生成dhParameterSpec（这步和发送方的initialize方式是不一样的）
			KeyPair receiverKeyPair = receiverKeyPairGenerator.generateKeyPair();
			PrivateKey receiverPrivateKey = receiverKeyPair.getPrivate(); //接收方的私钥
			byte[] receiverPublicKeyEnc = receiverKeyPair.getPublic().getEncoded();
//			System.out.println(Objects.equals(receiverPublicKey, receiverKeyPair.getPublic()));
			
			
			//3.密钥构建（接收方和发送方）
			KeyAgreement receiverKeyAgreement = KeyAgreement.getInstance("DH"); //接收方
			receiverKeyAgreement.init(receiverPrivateKey);
			receiverKeyAgreement.doPhase(receiverPublicKey, true);
			SecretKey receiverDESKey = receiverKeyAgreement.generateSecret("DES"); //使用DES方式加密(接收方）
			
			KeyFactory senderKeyFactory = KeyFactory.getInstance("DH"); //发送方
			x509EncodedKeySpec = new X509EncodedKeySpec(receiverPublicKeyEnc); //传入接收方的公钥数组
			PublicKey senderPublicKey = senderKeyFactory.generatePublic(x509EncodedKeySpec);

			KeyAgreement senderKeyAgreement = KeyAgreement.getInstance("DH"); //发送方
			senderKeyAgreement.init(senderKeyPair.getPrivate());
			senderKeyAgreement.doPhase(senderPublicKey, true);
			
			SecretKey senderDESKey = senderKeyAgreement.generateSecret("DES"); //使用DES方式加密（发送方）
			
//			System.out.println(Objects.equals(receiverDESKey, senderDESKey));
			
			//加密
			Cipher cipher = Cipher.getInstance("DES");
			cipher.init(Cipher.ENCRYPT_MODE, senderDESKey); //加密模式senderDESKey
			byte[] result = cipher.doFinal(src.getBytes());
			System.out.println("jdk dh encrpt:" + Base64.encodeBase64String(result));
			
			//解密
			cipher.init(Cipher.DECRYPT_MODE, receiverDESKey); //此处为解密模式，使用receiverDESKey
			result = cipher.doFinal(result); //得到解密后结果数组
			System.out.println("jdk dh decrypt:" + new String(result));
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}