一 对称加密缺点
密钥传递过程复杂，这是对称加密带来的困扰。
二 DH密钥交换算法特点
构建本地密钥
双方密钥一致
三 DH相关参数
四 DH算法实现过程
1、初始化发送方的密钥（KeyPairGenerator、KeyPair、PublicKey）
2、初始化接受方的密钥（KeyFactory、X509EncodedKeySpec、DHPublicKey、DHParameterSpec、KeyPairGenerator、PrivateKey）
3、密钥构建（KeyAgeement、SecretKey、KeyFactory、X509EncodeKeySpec、PublicKey）
4、加密和解密（Cipher）
五 DH代码实现过程
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 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;//import com.sun.org.apache.xalan.internal.utils.Objects;public class ImoocDH {private static String src = "cakin24 security dh";public static void main(String[] args) {jdkDH();}public static void jdkDH() {try {//1.初始化发送方密钥KeyPairGenerator senderKeyPairGenerator = KeyPairGenerator.getInstance("DH");senderKeyPairGenerator.initialize(512);KeyPair senderKeyPair = senderKeyPairGenerator.generateKeyPair();byte[] senderPublicKeyEnc = senderKeyPair.getPublic().getEncoded();//发送方公钥，发送给接收方（网络、文件。。。）//2.初始化接收方密钥KeyFactory receiverKeyFactory = KeyFactory.getInstance("DH");X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(senderPublicKeyEnc);PublicKey receiverPublicKey = receiverKeyFactory.generatePublic(x509EncodedKeySpec);DHParameterSpec dhParameterSpec = ((DHPublicKey)receiverPublicKey).getParams();KeyPairGenerator receiverKeyPairGenerator = KeyPairGenerator.getInstance("DH");receiverKeyPairGenerator.initialize(dhParameterSpec);KeyPair receiverKeypair = receiverKeyPairGenerator.generateKeyPair();PrivateKey receiverPrivateKey = receiverKeypair.getPrivate();byte[] receiverPublicKeyEnc = receiverKeypair.getPublic().getEncoded();//3.密钥构建KeyAgreement receiverKeyAgreement = KeyAgreement.getInstance("DH");receiverKeyAgreement.init(receiverPrivateKey);receiverKeyAgreement.doPhase(receiverPublicKey, true);SecretKey receiverDesKey = receiverKeyAgreement.generateSecret("DES");KeyFactory senderKeyFactory = KeyFactory.getInstance("DH");x509EncodedKeySpec = new X509EncodedKeySpec(receiverPublicKeyEnc);PublicKey senderPublicKey = senderKeyFactory.generatePublic(x509EncodedKeySpec);KeyAgreement senderKeyAgreement = KeyAgreement.getInstance("DH");senderKeyAgreement.init(senderKeyPair.getPrivate());senderKeyAgreement.doPhase(senderPublicKey, true);SecretKey senderDesKey = senderKeyAgreement.generateSecret("DES");//if (Objects.equals(receiverDesKey, senderDesKey)) {if(receiverDesKey.equals(senderDesKey)){System.out.println("双方密钥相同");}//4.加密Cipher cipher = Cipher.getInstance("DES");cipher.init(Cipher.ENCRYPT_MODE, senderDesKey);byte[] result = cipher.doFinal(src.getBytes());System.out.println("jdk dh encrypt : " + Base64.encodeBase64String(result));//5.解密cipher.init(Cipher.DECRYPT_MODE, receiverDesKey);result = cipher.doFinal(result);System.out.println("jdk dh decrypt : " + new String(result));} catch (Exception e) {e.printStackTrace();}}} 六 实现效果
双方密钥相同
jdk dh encrypt : wqnKvpQve05UD64OCQGXcQu5rcssEVSu
jdk dh decrypt : cakin24 security dh
七 应用场景
