慕课网_《Java实现非对称加密》学习总结

摘要：时间年月日星期三说明本文部分内容均来自慕课网。秘密密钥，生成一个分组的秘密密钥。

时间：2017年4月12日星期三
说明：本文部分内容均来自慕课网。@慕课网：http://www.imooc.com
教学示例源码：https://github.com/zccodere/s...
个人学习源码：https://github.com/zccodere/s...

非对称加密算法

</>复制代码 
高级
双保险
公钥、私钥
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

对称加密算法回顾

</>复制代码 
数据安全
密钥管理复杂
密钥传递过程复杂

非对称加密算法：DH（密钥交换）

</>复制代码 
对称加密带来的困扰
构建本地密钥
密钥对称

算法实现：

涉及相关类

</>复制代码 
初始化发送方密钥
    --KeyPairGenerator
    --KeyPair
    --PublicKey
初始化接收方密钥
    --KeyFactory
    --X509EncodedKeySpec
    --DHPublicKey
    --DHParameterSpec
    --KeyPairGenerator
    --PrivateKey
密钥构建
    --KeyAgreement：用来提供密钥一致性（或密钥交换）协议的功能。
    --SecretKey：秘密密钥，生成一个分组的秘密密钥。
    --KeyFactory
    --X509EncodedKeySpec
    --PublicKey
加密、解密
    --Cipher：为加密解密提供密码功能的类

代码演示：

</>复制代码 
package com.myimooc.security.dh;
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import javax.crypto.KeyAgreement;
import javax.crypto.SecretKey;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;
import java.security.*;
import java.security.spec.X509EncodedKeySpec;
/**
 * DH非对称加密演示
 * Created by ZC on 2017/4/12.
 */
public class DemoDH {
    /** 待加密字符串 */
    private static String src="imooc security dh";
    public static void main(String[] args){
        jdkDH();
    }
    /** 使用jdk实现DH非对称加密 */
    public static void jdkDH(){
        try {
            // 1.初始化发送方密钥
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DH");
            keyPairGenerator.initialize(512);
            KeyPair senderKerPair = keyPairGenerator.generateKeyPair();
            // 发送方公钥，发送给接收方（网络、文件...）
            byte[] senderPublicKeyEnc = senderKerPair.getPublic().getEncoded();
            // 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(senderKerPair.getPrivate());
            senderKeyAgreement.doPhase(senderPublicKey,true);
            SecretKey senderDesKey = senderKeyAgreement.generateSecret("DES");
//            if(Objects.equals(receiverDesKey,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();
        }
    }
}

流程演示：

非对称加密算法：RSA

</>复制代码 
唯一广泛接受并实现
数据加密&数字签名
公钥加密、私钥解密
私钥加密、公钥解密

算法实现：

代码演示：

</>复制代码 
package com.myimooc.security.rsa;
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
 * RSA非对称加密演示
 * Created by ZC on 2017/4/12.
 */
public class DemoRSA {
    /** 待加密字符串 */
    private static String src="imooc security rsa";
    public static void main(String[] args){
        jdkRSA();
    }
    public static void jdkRSA(){
        try{
            // 1.初始化密钥
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(512);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
            // 2.私钥加密、公钥解密：加密
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE,privateKey);
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("私钥加密、公钥解密：加密:"+ Base64.encodeBase64String(result));
            // 3.私钥加密、公钥解密：解密
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            cipher.init(Cipher.DECRYPT_MODE,publicKey);
            result = cipher.doFinal(result);
            System.out.println("私钥加密、公钥解密：解密:"+ new String(result));
            // 4.公钥加密、私钥解密：加密
            x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            keyFactory = KeyFactory.getInstance("RSA");
            publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            cipher.init(Cipher.ENCRYPT_MODE,publicKey);
            result = cipher.doFinal(src.getBytes());
            System.out.println("公钥加密、私钥解密：加密:"+ Base64.encodeBase64String(result));
            // 5.公钥加密、私钥解密：解密
            pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            keyFactory = KeyFactory.getInstance("RSA");
            privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE,privateKey);
            result = cipher.doFinal(result);
            System.out.println("公钥加密、私钥解密：解密:"+ new String(result));
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

流程演示：

非对称加密算法：ELGamal

</>复制代码 
公钥加密算法
Bouncy Castle

算法实现：

部分代码演示：

</>复制代码 
package com.myimooc.security.elgamal;
import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import javax.crypto.Cipher;
import javax.crypto.spec.DHParameterSpec;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
 * ELGamal非对称加密演示
 * Created by ZC on 2017/4/12.
 */
public class DemoELGamal {
    /** 待加密字符串 */
    private static String src="imooc security elgamal";
    public static void main(String[] args)throws Exception{
        bcELGamal();
    }
    /** 使用 BouncyCastle 实现 ELGamal 加解密 */
    public static void bcELGamal()throws Exception{
        // 公钥加密，私钥解密
        Security.addProvider(new BouncyCastleProvider());
        // 1.初始化密钥
        AlgorithmParameterGenerator algorithmParameterGenerator = AlgorithmParameterGenerator.getInstance("ELGamal");
        algorithmParameterGenerator.init(256);
        AlgorithmParameters algorithmParameters = algorithmParameterGenerator.generateParameters();
        DHParameterSpec dhParameterSpec = (DHParameterSpec) algorithmParameters.getParameterSpec(DHParameterSpec.class);
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ELGamal");
        keyPairGenerator.initialize(dhParameterSpec,new SecureRandom());
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();
        System.out.println("Public Key:"+ Base64.encodeBase64String(publicKey.getEncoded()));
        System.out.println("Private Key:"+ Base64.encodeBase64String(privateKey.getEncoded()));
    }
}

流程演示：

非对称加密算法：回顾

</>复制代码 
公钥、私钥
DH（Diffie-Hellman）密钥交换算法
RSA基于因子分解
ElGamal基于离散对数