JAVA实现对称加密

概括:对称加密指加密和解密使用相同密钥的加密算法。本课程中将介绍DES、3重DES、AES和PBE几种常见的对称加密算法在Java中的实现,以及他们的应用范围。对称加密算法是初等的加密算法,安全性并不是那么的高


一、对称加密算法DES(数据加密标准)

JAVA实现对称加密_第1张图片

package com.nelson.des;

import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.xml.bind.annotation.adapters.HexBinaryAdapter;

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

public class DESTest {
	//定义一个要加密的字符串
	private static final String password = "xiehuaxin123456";

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		jdkDES();
	}

	//JDK的实现
	public static void jdkDES() {
		try {
			//1.生成KEY
			KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");//Key的生成器 
			keyGenerator.init(56);//指定keySize
			SecretKey secretKey = keyGenerator.generateKey();
			byte[] bytesKey = secretKey.getEncoded();
			
			//2.KEY转换
			DESKeySpec desKeySpec = new DESKeySpec(bytesKey);//实例化DESKey秘钥的相关内容
			SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");//实例一个秘钥工厂,指定加密方式
			Key convertSecretKey = factory.generateSecret(desKeySpec);
			
			
			//3.加密    DES/ECB/PKCS5Padding--->算法/工作方式/填充方式
			Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");//通过Cipher这个类进行加解密相关操作
			cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);
			byte[] result = cipher.doFinal(password.getBytes());//输入要加密的内容
			System.out.println("加密的结果:" + Hex.encodeHexString(result));
			
			//4.解密
			cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);
			result = cipher.doFinal(result);
			System.out.println("解密结果:" + new String(result));
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	//BC的实现
	public static void bcDES() {
		try {
			Security.addProvider(new BouncyCastleProvider());
			
			//1.生成KEY
			KeyGenerator keyGenerator = KeyGenerator.getInstance("DES","BC");
			keyGenerator.init(56);
			SecretKey secretKey = keyGenerator.generateKey();
			byte[] bytesKey = secretKey.getEncoded();
			
			//2.转换KEY
			DESKeySpec desKeySpec = new DESKeySpec(bytesKey);
			SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
			Key convertKey = factory.generateSecret(desKeySpec);
			
			//3.加密
			Cipher cipher = Cipher.getInstance("/DES/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, convertKey);
			byte[] result = cipher.doFinal(password.getBytes());
			System.out.println(Hex.encodeHexString(result));
			
			//4.解密
			cipher.init(Cipher.DECRYPT_MODE,convertKey);
			result = cipher.doFinal(result);
			System.out.println(new String(result));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
}

二、对称加密算法3DES

    2.1 三重DES相对于DES的好处有:秘钥长度增强、迭代次数提高

JAVA实现对称加密_第2张图片

package com.nelson.des;

import java.security.Key;
import java.security.NoSuchAlgorithmException;
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;

public class ThreeDESTest {

	private static final String password = "xiehuaxin1124";
	public static void main(String[] args) {
		jdkThreeDES();
	}
	
	public static void jdkThreeDES() {
		try {
			//1.生成KEY
			KeyGenerator keyGenerator = KeyGenerator.getInstance("DESEde");
//			keyGenerator.init(168);
			keyGenerator.init(new SecureRandom());
			SecretKey secretKey = keyGenerator.generateKey();
			byte[] bytesKey = secretKey.getEncoded();
			
			//2.转换KEY
			DESedeKeySpec deSedeKeySpec = new DESedeKeySpec(bytesKey);
			SecretKeyFactory factory = SecretKeyFactory.getInstance("DESEde");
			Key convertKey = factory.generateSecret(deSedeKeySpec);
			
			//3.加密
			Cipher cipher = Cipher.getInstance("DESEde/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, convertKey);
			byte[] result = cipher.doFinal(password.getBytes());
			System.out.println("加密后:" + Hex.encodeHexString(result));
			
			//4.解密
			cipher.init(Cipher.DECRYPT_MODE, convertKey);
			result = cipher.doFinal(result);
			System.out.println("解密后:" + new String(result));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

三、对称加密算法AES

AES使用的最多的对称加密算法,AES的优势之一是至今尚未被破解。AES通常用于移动通信系统加密以及基于SSH协议的软件。

JAVA实现对称加密_第3张图片

package com.nelson.jiami;

import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Base64;

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

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

public class AESTest {

	private static String password = "xiehuaxin";
	
	public static void main(String[] args) {
		jdkAES();
		
	}
	
	public static void jdkAES() {
		try {
			//1.生成KEY
			KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
			keyGenerator.init(new SecureRandom());
			SecretKey secretKey = keyGenerator.generateKey();
			byte[] byteKey = secretKey.getEncoded();

			//2.转换KEY
			Key key = new SecretKeySpec(byteKey,"AES");
			
			//3.加密
			Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] result = cipher.doFinal(password.getBytes());
			System.out.println("加密后:" + Hex.encodeHexString(result));
			
			//4.解密
			cipher.init(Cipher.DECRYPT_MODE, key);
			result = cipher.doFinal(result);
			System.out.println("解密后:" + new String(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

四、对称加密算法PBE

PBE(Password Based Encryption 基于口令加密)算法结合了消息摘要算法和对称加密算法的优点。但是口令还是有可能被穷举出来,所以一般通过加盐salt的方式进行加密。PBE算法只是对已有算法进行了包装,通常有JDK和BC 两种实现。

JAVA实现对称加密_第4张图片

JAVA实现对称加密_第5张图片

package com.nelson.jiami;

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

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

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

public class PBETest {

	private static String src = "xiehuaxin";//待加密的字符串
	
	public static void main(String[] args) {
		jdkPBE();
	}

	public static void jdkPBE() {
		try {
			//1. 初始化盐
			SecureRandom secureRandom = new SecureRandom();
			byte[] salt = secureRandom.generateSeed(8);
			
			
			//2. 口令与秘钥
			//2.1 定义密码
			String password = "NELSON";//这个是加密用的口令
			//2.2 把密码转换成秘钥
			PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());
			SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWITHMD5andDES");
			Key key = factory.generateSecret(pbeKeySpec);
			
			//3. 加密
			PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, 100);//100是你选择迭代的次数
			Cipher cipher = Cipher.getInstance("PBEWITHMD5andDES");
			cipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);
			byte[] result = cipher.doFinal(src.getBytes());
			System.out.println("加密后:" + Hex.encodeHexString(result));
			
			//4.解密
			cipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);
			result = cipher.doFinal(result);
			System.out.println("解密后:" + new String(result));
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
}

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