Java对称加密算法

1.DES对称加密算法

（1）DES概述

（2）DES应用场景

（3）DES算法实现

package com.java.security.des;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

import org.apache.commons.codec.binary.Hex;
import org.junit.Test;

public class DESTest {
	
	private String text="Jasper is a good student!";
	
	@Test
	public void testJDKDES(){
		try {
			//生成Key
			KeyGenerator keyGenerator=KeyGenerator.getInstance("DES");
			keyGenerator.init(56);//JDKDES实现--密钥长度默认是56位
			SecretKey secretKey=keyGenerator.generateKey();
			byte[] bytesKey=secretKey.getEncoded();
			
			//Key转换
			DESKeySpec desKeySpec=new DESKeySpec(bytesKey);
			SecretKeyFactory factory=SecretKeyFactory.getInstance("DES");
			SecretKey convertSecretKey=factory.generateSecret(desKeySpec);
			
			//加密
			Cipher cipher=Cipher.getInstance("DES/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);
			byte[] result=cipher.doFinal(text.getBytes());
			System.out.println("加密："+Hex.encodeHexString(result));
			
			//解密
			cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);
			result=cipher.doFinal(result);
			System.out.println("解密："+new String(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}

}

（4）DES算法弊端

a>违反柯克霍夫原则（数据的安全基于密钥而不是算法的保密）

b>安全问题

2.3重DES对称加密算法

（1）3重DES概述

（2）3重DES算法实现

package com.java.security.des;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;

import org.apache.commons.codec.binary.Hex;
import org.junit.Test;

public class My3DESTest {
	
private String text="Jasper is a good student!";
	
	@Test
	public void testJDK3DES(){
		try {
			//生成Key
			KeyGenerator keyGenerator=KeyGenerator.getInstance("DESede");
			//keyGenerator.init(56);//JDKDES实现--密钥长度默认是56位
			keyGenerator.init(new SecureRandom());//根据加密方式随机生成一个长度
			SecretKey secretKey=keyGenerator.generateKey();
			byte[] bytesKey=secretKey.getEncoded();
			
			//Key转换
			DESedeKeySpec desKeySpec=new DESedeKeySpec(bytesKey);
			SecretKeyFactory factory=SecretKeyFactory.getInstance("DESede");
			SecretKey convertSecretKey=factory.generateSecret(desKeySpec);
			
			//加密
			Cipher cipher=Cipher.getInstance("DESede/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);
			byte[] result=cipher.doFinal(text.getBytes());
			System.out.println("加密："+Hex.encodeHexString(result));
			
			//解密
			cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);
			result=cipher.doFinal(result);
			System.out.println("解密："+new String(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}

}

（3）3重DES弊端

a>速度慢

b>效率低

3.AES算法（推荐使用）

（1）AES算法概述

（2）AES算法应用场景

（3）AES算法实现

package com.java.security.aes;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;
import org.junit.Test;

public class AESTest {
	
	private String text="Jasper is a good student!";
	
	@Test
	public void testJDKAES(){
		try {
			//生成Key
			KeyGenerator keyGenerator=KeyGenerator.getInstance("AES");
			keyGenerator.init(new SecureRandom());
			SecretKey secretKey=keyGenerator.generateKey();
			byte[] bytesKey=secretKey.getEncoded();
			
			//转换Key
			Key key=new SecretKeySpec(bytesKey, "AES");
			
			//加密
			Cipher cipher=Cipher.getInstance("AES/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] result=cipher.doFinal(text.getBytes());
			System.out.println("加密1："+Base64.encodeBase64String(result));
			System.out.println("加密2："+Hex.encodeHexString(result));
			
			//解密
			cipher.init(Cipher.DECRYPT_MODE, key);
			result=cipher.doFinal(result);
			System.out.println("解密："+new String(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

4.PBE对称加密算法（已有加密算法的整合）

（1）PBE算法概述

（2）PBE算法实现

package com.java.security.pbe;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import org.apache.commons.codec.binary.Hex;
import org.junit.Test;

public class PBETest {
	
	private String text="Jasper is a good student!";
	
	@Test
	public void testJDKPBE(){
		try {
			//初始化盐
			SecureRandom random=new SecureRandom();
			byte[] salt=random.generateSeed(8);
			
			//口令与密钥
			String password="Jasper";
			PBEKeySpec pbeKeySpec=new PBEKeySpec(password.toCharArray());
			SecretKeyFactory factory=SecretKeyFactory.getInstance("PBEWITHMD5andDES");
			SecretKey key=factory.generateSecret(pbeKeySpec);
			
			//加密
			PBEParameterSpec parameterSpec=new PBEParameterSpec(salt, 100);
			Cipher cipher=Cipher.getInstance("PBEWITHMD5andDES");
			cipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);
			byte[] result=cipher.doFinal(text.getBytes());
			System.out.println("加密："+Hex.encodeHexString(result));
			
			//解密
			cipher.init(Cipher.DECRYPT_MODE, key,parameterSpec);
			result=cipher.doFinal(result);
			System.out.println("解密："+new String(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
	

}