常用对称加密算法-DES

详细介绍：http://blog.csdn.net/cc41798520101/article/details/53673681

package com.test;

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

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

import org.apache.commons.codec.binary.Base64;

public class DESUtil {

//算法名称
public static final String KEY_ALGORITHM = "DES";
//算法名称/加密模式/填充方式
//DES共有四种工作模式-->>ECB：电子密码本模式、CBC：加密分组链接模式、CFB：加密反馈模式、OFB：输出反馈模式
//public static final String CIPHER_ALGORITHM = "DES/ECB/NoPadding";
public static final String CIPHER_ALGORITHM = "DES/ECB/PKCS5Padding";
//KEY
//public static final String KEY = "A1B2C3D4E5F60708";
public static final String KEY = "wadasdsadasdaadsaas";
/**
* 加密数据
* @param data 待加密数据
* @param key 密钥
* @return 加密后的数据
*/
/*public static String encrypt(String data, String key) throws Exception {
Key deskey = keyGenerator(key);*/
public static String encrypt(String data) throws Exception {
Key deskey = keyGenerator(DESUtil.KEY);
// 实例化Cipher对象，它用于完成实际的加密操作
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
SecureRandom random = new SecureRandom();
// 初始化Cipher对象，设置为加密模式
cipher.init(Cipher.ENCRYPT_MODE, deskey, random);
byte[] results = cipher.doFinal(data.getBytes("utf-8"));
// 执行加密操作。加密后的结果通常都会用Base64编码进行传输
return Base64.encodeBase64String(results);
}

/**
* 解密数据
* @param data 待解密数据
* @param key 密钥
* @return 解密后的数据
*/
/*public static String decrypt(String data, String key) throws Exception {
Key deskey = keyGenerator(key);*/
public static String decrypt(String data) throws Exception {
Key deskey = keyGenerator(DESUtil.KEY);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
//初始化Cipher对象，设置为解密模式
cipher.init(Cipher.DECRYPT_MODE, deskey);
// 执行解密操作
return new String(cipher.doFinal(Base64.decodeBase64(data)));
}

/**
*
* 生成密钥key对象
* @param KeyStr 密钥字符串
* @return 密钥对象
* @throws InvalidKeyException
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
* @throws Exception
*/
private static SecretKey keyGenerator(String keyStr) throws Exception {
//byte input[] = hexString2Bytes(keyStr);
byte input[] = keyStr.getBytes();
DESKeySpec desKey = new DESKeySpec(input);
//创建一个密匙工厂，然后用它把DESKeySpec转换成SecretKey
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey securekey = keyFactory.generateSecret(desKey);
return securekey;
}

// 从十六进制字符串到字节数组转换
public static byte[] hexString2Bytes(String hexstr) {
byte[] b = new byte[hexstr.length() / 2];
int j = 0;
for (int i = 0; i < b.length; i++) {
char c0 = hexstr.charAt(j++);
char c1 = hexstr.charAt(j++);
b[i] = (byte) ((parse(c0) << 4) | parse(c1));
}
return b;
}

private static int parse(char c) {
if (c >= 'a') return (c - 'a' + 10) & 0x0f;
if (c >= 'A') return (c - 'A' + 10) & 0x0f;
return (c - '0') & 0x0f;
}
}