DH加密算法

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加密算法
package test.common;

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

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

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


/**
 * 非对称加密算法DH算法组件
 * 非对称算法一般是用来传送对称加密算法的密钥来使用的，所以这里我们用DH算法模拟密钥传送 
 * 原理：甲方生产随机公私钥，乙方用甲方的公钥生成乙方的公私钥对
 * 甲方用甲方的私钥和乙方的公钥生成密钥，乙方用乙方的私钥和甲方的公钥生成密钥
 * 甲乙双方在用密钥DES对称加密
 * 对称加密DES算法继续做我们的数据加解密 
 * @author nicaisheng
 *
 */
public class DHCoderTest {
	//非对称密钥算法  
	public static final String KEY_ALGORITHM = "DH";
	
	//本地密钥算法，即对称加密算法。可选des，aes，desede  
	public static final String SECRET_ALGORITHM = "DES";
	
	/** 
     * 密钥长度，DH算法的默认密钥长度是1024 
     * 密钥长度必须是64的倍数，在512到1024位之间 
     * */
	private static final int KEY_SIZE = 512;
	
	//公钥
	private static final String PUBLIC_KEY="DHPublicKey"; 
	
	//私钥  
    private static final String PRIVATE_KEY="DHPrivateKey"; 
    
    /**
     * 初始化甲方密钥
     * @return
     * @throws Exception
     */
    public static Map<String,Object> initKey() throws Exception{
    	//实例化密钥生成器
    	KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
    	//初始化密钥生成器
    	keyPairGenerator.initialize(KEY_SIZE);
    	//生成密钥对
    	KeyPair keyPair = keyPairGenerator.generateKeyPair();
    	//甲方公钥
    	DHPublicKey publicKey = (DHPublicKey) keyPair.getPublic();
    	//甲方私钥
    	DHPrivateKey privateKey = (DHPrivateKey) keyPair.getPrivate();
    	//将密钥存储在map中  
        Map<String,Object> keyMap=new HashMap<String,Object>();
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    	
    }
    
    /** 
     * 初始化乙方密钥 
     * @param key 甲方密钥（这个密钥是通过第三方途径传递的） 
     * @return Map 乙方密钥的Map 
     * */ 
    public static Map<String,Object> initKey(byte[] key) throws Exception{
    	//解析甲方的公钥  
        //转换公钥的材料
    	X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
    	//实例化密钥工厂
    	KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    	//产生公钥
    	PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
    	//由甲方的公钥构造乙方密钥
    	DHParameterSpec dhParamSpec = ((DHPublicKey)pubKey).getParams();
    	//实例化密钥生成器
    	KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(keyFactory.getAlgorithm());
    	//初始化密钥生成器
    	keyPairGenerator.initialize(dhParamSpec);
    	//产生密钥对
    	KeyPair keyPair = keyPairGenerator.generateKeyPair();
    	//乙方公钥  
        DHPublicKey publicKey=(DHPublicKey)keyPair.getPublic();  
        //乙方私钥  
        DHPrivateKey privateKey=(DHPrivateKey)keyPair.getPrivate();  
        //将密钥存储在Map中  
        Map<String,Object> keyMap=new HashMap<String,Object>();  
        keyMap.put(PUBLIC_KEY, publicKey);  
        keyMap.put(PRIVATE_KEY, privateKey);  
        return keyMap;
    }
    
    /** 
     * 加密 
     * @param data待加密数据 
     * @param key 密钥 
     * @return byte[] 加密数据 
     * */
    public static byte[] encrypt(byte[] data,byte[] key) throws Exception{
    	//生成本地密钥
    	SecretKey secretKey = new SecretKeySpec(key,SECRET_ALGORITHM);
    	//数据加密
    	Cipher cipher = Cipher.getInstance(secretKey.getAlgorithm());
    	cipher.init(Cipher.ENCRYPT_MODE, secretKey);
    	return cipher.doFinal(data);
    }
    
    /** 
     * 解密 
     * @param data 待解密数据 
     * @param key 密钥 
     * @return byte[] 解密数据 
     * */  
    public static byte[] decrypt(byte[] data,byte[] key) throws Exception{  
        //生成本地密钥  
        SecretKey secretKey=new SecretKeySpec(key,SECRET_ALGORITHM);  
        //数据解密  
        Cipher cipher=Cipher.getInstance(secretKey.getAlgorithm());  
        cipher.init(Cipher.DECRYPT_MODE, secretKey);  
        return cipher.doFinal(data);  
    }  
    
    /** 
     * 构建密钥 
     * @param publicKey 公钥 
     * @param privateKey 私钥 
     * @return byte[] 本地密钥 
     * */
    public static byte[] getSecretKey(byte[] publicKey,byte[] privateKey) throws Exception{
    	//实例化密钥工厂
    	KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    	//初始化公钥  
        //密钥材料转换
    	X509EncodedKeySpec x509KeySpec=new X509EncodedKeySpec(publicKey);
    	//产生公钥  
        PublicKey pubKey=keyFactory.generatePublic(x509KeySpec);
        //初始化私钥  
        //密钥材料转换  
        PKCS8EncodedKeySpec pkcs8KeySpec=new PKCS8EncodedKeySpec(privateKey);  
        //产生私钥  
        PrivateKey priKey=keyFactory.generatePrivate(pkcs8KeySpec);
        //实例化
        KeyAgreement keyAgree = KeyAgreement.getInstance(keyFactory.getAlgorithm());
        //初始化
        keyAgree.init(priKey);
        keyAgree.doPhase(pubKey, true);
        
        //生成本地密钥
        SecretKey secretKey = keyAgree.generateSecret(SECRET_ALGORITHM);
        return secretKey.getEncoded();
    }
    
    /** 
     * 取得私钥 
     * @param keyMap 密钥map 
     * @return byte[] 私钥 
     * */  
    public static byte[] getPrivateKey(Map<String,Object> keyMap){  
        Key key=(Key)keyMap.get(PRIVATE_KEY);  
        return key.getEncoded();  
    }  
    /** 
     * 取得公钥 
     * @param keyMap 密钥map 
     * @return byte[] 公钥 
     * */  
    public static byte[] getPublicKey(Map<String,Object> keyMap) throws Exception{  
        Key key=(Key) keyMap.get(PUBLIC_KEY);  
        return key.getEncoded();  
    }
    
    public static void main(String[] args) throws Exception {
    	//生成甲方的密钥对
    	Map<String,Object> keyMap1 = DHCoderTest.initKey();
    	byte[] publicKey1 = DHCoderTest.getPublicKey(keyMap1);
    	byte[] privateKey1 = DHCoderTest.getPrivateKey(keyMap1);
    	System.out.println("甲方公钥："+Base64.encodeBase64String(publicKey1));
    	System.out.println("甲方私钥："+Base64.encodeBase64String(privateKey1));
    	
    	//由甲方的公钥产生的密钥对 
    	Map<String,Object> keyMap2 = DHCoderTest.initKey(publicKey1);
    	byte[] publicKey2 = DHCoderTest.getPublicKey(keyMap2);
    	byte[] privateKey2 = DHCoderTest.getPrivateKey(keyMap2);
    	System.out.println("乙方公钥："+Base64.encodeBase64String(publicKey2));
    	System.out.println("乙方私钥："+Base64.encodeBase64String(privateKey2));
    	
    	//组装甲方的本地加密密钥,由乙方的公钥和甲方的私钥组合而成
    	byte[] key1=DHCoderTest.getSecretKey(publicKey2, privateKey1);
    	System.out.println("甲方的本地密钥："+Base64.encodeBase64String(key1));  
    	
    	//组装乙方的本地加密密钥，由甲方的公钥和乙方的私钥组合而成  
        byte[] key2=DHCoderTest.getSecretKey(publicKey1, privateKey2);  
        System.out.println("乙方的本地密钥："+Base64.encodeBase64String(key2));
        
        System.out.println("甲方的本地密钥==乙方的本地密钥:"+Base64.encodeBase64String(key1).equals(Base64.encodeBase64String(key2)));
        System.out.println("================密钥对构造完毕，开始进行加密数据的传输=============");
        
        String str = "密码交换算法";
        System.out.println("原文："+str);
        
        System.out.println("===========使用甲方本地密钥对进行数据加密=============="); 
        byte[] code1 = DHCoderTest.encrypt(str.getBytes(), key1);
        System.out.println("加密后的数据："+Base64.encodeBase64String(code1));
        
        System.out.println("===========使用乙方本地密钥对数据进行解密=============="); 
        byte[] decode1 = DHCoderTest.decrypt(code1, key2);
        System.out.println("乙方解密后的数据："+new String(decode1));
        
        
	}
}
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