Java加解密-DH非对称加密算法

非对称加密算法

　　加密密钥分为公钥和私钥。可以使用公钥加密私钥解密，也可以使用私钥加密公钥解密。非对称加密算法主要有：DH（Diffie-Hellman）密钥交换算法、RSA（基于因子分解）、Elgamal（基于离散对数）、ECC（Elliptical Curve Cryptography，椭圆曲线加密）。

DH（密钥交换）算法

　　如何安全地传送密钥是对称加密算法的症结所在。密钥交换算法是通过构建本地密钥来解决对称加密算法中的密钥传递的问题的。

　　实现该算法的步骤和所需要的类如下：

1.初始化发送方密钥
-KeyPairGenerator
-KeyPair（密钥载体，密钥对，包括公约和私钥）
-PublicKey
2.初始化接收方密钥
-KeyFactory（可以生成公钥和私钥）
-X509EncodedKeySpec（根据ASN.1标准进行密钥编码）
-DHPublicKey
-DHParameterSpec
-KeyPairGenerator
-PrivateKey
3.密钥构建
-KeyAgreement（提供密钥一致性或密钥交换协议的功能）
-SecretKey（生成一个分组的秘密密钥）
-KeyFactory
-X509EncodedKeySpec
-PublicKey
4.加解密
-Cipher（JCE框架的核心）

应用场景：

 　　具体实现：

============================================================================DH加解密工具类：

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
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.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.interfaces.DHPrivateKey;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class SecurityDH {
    
    /** 使用DH方式加解密的前提条件：否则报错 java.security.NoSuchAlgorithmException: Unsupported secret key algorithm: AES
     *     1.当前开发环境中的运行的java程序, 在jre中配置缺省VM变量 -Djdk.crypto.KeyAgreement.legacyKDF=true
     *         A.点击窗口，选择首选项  B.点击installed JREs, 选择JRE配置，然后编辑  C.在缺省VM参数：-Djdk.crypto.KeyAgreement.legacyKDF=true
     *  2.可运行jar包，则需要在运行时采用命令提示符运行，在运行时添加VM参数，运行命令为：java -jar -Djdk.crypto.KeyAgreement.legacyKDF=true jarPackName.jar
     *         A.编辑可执行文件，配置VM参数：-Djdk.crypto.KeyAgreement.legacyKDF=true
     */
    
    /** 本地密钥算法，即对称加密密钥算法  可选DES、DESede或者AES*/
    private static final String SELECT_ALGORITHM = "AES";
    /** 默认的加密算法 */
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";
    /** 密钥长度 */
    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 Map 甲方密钥Map
     * @throws Exception
     */
    public static Map<String, Object> initKey() {
        try {
            //实例化密钥对生成器
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DH");
            //初始化密钥对生成器
            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();
            //将密钥对存储在Map中
            Map<String, Object> keyMap = new HashMap<String, Object>(2);
            keyMap.put(PUBLIC_KEY, publicKey);
            keyMap.put(PRIVATE_KEY, privateKey);
            return keyMap;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
 
    /** 初始化乙方密钥
     * @param key 甲方公钥
     * @return Map 乙方密钥Map
     * @throws Exception
     */
    public static Map<String, Object> initKey(byte[] key) {
        try {
            //解析甲方公钥
            //转换公钥材料
            X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
            //实例化密钥工厂
            KeyFactory keyFactory = KeyFactory.getInstance("DH");
            //产生公钥
            PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
            //由甲方公钥构建乙方密钥
            DHParameterSpec dhParameterSpec = ((DHPublicKey) pubKey).getParams();
            //实例化密钥对生成器
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DH");
            //初始化密钥对生成器
            keyPairGenerator.initialize(dhParameterSpec);
            //产生密钥对
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            //乙方公钥
            DHPublicKey publicKey = (DHPublicKey) keyPair.getPublic();
            //乙方私约
            DHPrivateKey privateKey = (DHPrivateKey) keyPair.getPrivate();
            //将密钥对存储在Map中
            Map<String, Object> keyMap = new HashMap<String, Object>(2);
            keyMap.put(PUBLIC_KEY, publicKey);
            keyMap.put(PRIVATE_KEY, privateKey);
            return keyMap;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
 
    /** 生成加密秘钥
     * @return
     */
    private static SecretKeySpec getSecretKey(final byte[] key) {
        //返回生成指定算法密钥生成器的 KeyGenerator 对象
        KeyGenerator kg = null;
        try {
            kg = KeyGenerator.getInstance(SELECT_ALGORITHM);
            //AES 要求密钥长度为 128
            kg.init(128, new SecureRandom(key));
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            return new SecretKeySpec(secretKey.getEncoded(), SELECT_ALGORITHM);// 转换为AES专用密钥
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
 
        return null;
    }
 
    /** 加密
     * @param data 待加密数据
     * @param key  密钥
     * @return byte[] 加密数据
     * @throws Exception
     */
    public static byte[] encrypt(byte[] data, byte[] key) {
        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器
            byte[] byteContent = data;
            cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(key));// 初始化为加密模式的密码器
            byte[] result = cipher.doFinal(byteContent);// 加密
            return result;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return null;
    }
 
    /**  解密
     * @param data 待解密数据
     * @param key  密钥
     * @return byte[] 解密数据
     * @throws Exception
     */
    public static byte[] decrypt(byte[] data, byte[] key) {
        try {
            //实例化
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            //使用密钥初始化，设置为解密模式
            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key));
            //执行操作
            byte[] result = cipher.doFinal(data);
            return result;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return null;
    }
 
    /** 构建密钥
     * @param publicKey  公钥
     * @param privateKey 私钥
     * @return byte[] 本地密钥
     * @throws Exception
     */
    public static byte[] getSecretKey(byte[] publicKey, byte[] privateKey) {
        try {
            //实例化密钥工厂
            KeyFactory keyFactory = KeyFactory.getInstance("DH");
            //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(SELECT_ALGORITHM);
            return secretKey.getEncoded();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
 
    /** 取得私钥
     * @param keyMap 密钥Map
     * @return byte[] 私钥
     * @throws Exception
     */
    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
     * @throws Exception
     */
    public static byte[] getPublicKey(Map<String, Object> keyMap) {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return key.getEncoded();
    }
}

============================================================================DH加解密工具测试类：

    @Test
    public void test_DH() {
        //甲方公钥
        byte[] publicKeyA;
        //甲方私钥
        byte[] privateKeyA;
        //甲方本地密钥
        byte[] localKeyA;
        //乙方公钥
        byte[] publicKeyB;
        //乙方私钥
        byte[] privateKeyB;
        //乙方本地密钥
        byte[] localKeyB;
 
        //初始化密钥
        //生成甲方密钥对
        Map<String, Object> keyMapA = SecurityDH.initKey();
        publicKeyA = SecurityDH.getPublicKey(keyMapA);
        privateKeyA = SecurityDH.getPrivateKey(keyMapA);
        System.out.println("甲方公钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(publicKeyA));
        System.out.println("甲方私钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(privateKeyA));
        //由甲方公钥产生乙方本地密钥对
        Map<String, Object> keyMapB = SecurityDH.initKey(publicKeyA);
        publicKeyB = SecurityDH.getPublicKey(keyMapB);
        privateKeyB = SecurityDH.getPrivateKey(keyMapB);
        System.out.println("乙方公钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(publicKeyB));
        System.out.println("乙方私钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(privateKeyB));
        localKeyA = SecurityDH.getSecretKey(publicKeyB, privateKeyA);
        System.out.println("甲方本地密钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(localKeyA));
        localKeyB = SecurityDH.getSecretKey(publicKeyA, privateKeyB);
        System.out.println("乙方本地密钥:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(localKeyB));
 
        System.out.println();
        System.out.println("===甲方向乙方发送加密数据===");
        String msgA2B = "求知若饥，虚心若愚。";
        System.out.println("原文:\n" + msgA2B);
        System.out.println("---使用甲方本地密钥对数据进行加密---");
        //使用甲方本地密钥对数据加密
        byte[] encodeMsgA2B = SecurityDH.encrypt(msgA2B.getBytes(), localKeyA);
        System.out.println("加密:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(encodeMsgA2B));
        System.out.println("---使用乙方本地密钥对数据库进行解密---");
        //使用乙方本地密钥对数据进行解密
        byte[] msgB2A = SecurityDH.decrypt(encodeMsgA2B, localKeyB);
        String output1 = new String(msgB2A);
        System.out.println("解密:\n" + output1);
 
        System.out.println("/~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~..~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~/");
        System.out.println("===乙方向甲方发送加密数据===");
        String input2 = "好好学习，天天向上。";
        System.out.println("原文:\n" + input2);
        System.out.println("---使用乙方本地密钥对数据进行加密---");
        //使用乙方本地密钥对数据进行加密
        byte[] encode2 = SecurityDH.encrypt(input2.getBytes(), localKeyB);
        System.out.println("加密:\n" + org.apache.commons.codec.binary.Base64.encodeBase64String(encode2));
        System.out.println("---使用甲方本地密钥对数据进行解密---");
        //使用甲方本地密钥对数据进行解密
        byte[] decode2 = SecurityDH.decrypt(encode2, localKeyA);
        String output2 = new String(decode2);
        System.out.println("解密:\n" + output2);
    }