一、对称加密算法DES（数据加密标准）

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

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。

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。

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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