java密钥交换算法DH定义与应用实例分析

本文实例讲述了java密钥交换算法dh定义与应用。分享给大家供大家参考，具体如下：

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

ps：关于加密解密感兴趣的朋友还可以参考本站在线工具：

文字在线加密解密工具（包含aes、des、rc4等）：

md5在线加密工具:
http://tools.jb51.net/password/createmd5password

在线散列/哈希算法加密工具:

在线md5/hash/sha-1/sha-2/sha-256/sha-512/sha-3/ripemd-160加密工具：

在线sha1/sha224/sha256/sha384/sha512加密工具：