DES加密解密

package com.mall.common;

import java.security.Key;
import java.security.Security;
import javax.crypto.Cipher;


public class DesUtils {
    
    public static final String ALGORITHM = "DES";
    private static final String DEFAULT_KEY = "eCpBr.C8";  //8位

    
    public static Key getKey(String strKey) throws Exception {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        return getKey(strKey.getBytes());
    }
    
    
    /**
     * 从指定字符串生成密钥，密钥所需的字节数组长度为8位 不足8位时后面补0，超出8位只取前8位
     *
     * @param arrBTmp 构成该字符串的字节数组
     * @return 生成的密钥
     * @throws Exception
     */
    private static Key getKey(byte[] arrBTmp) throws Exception {
        // 创建一个空的8位字节数组（默认值为0）
        byte[] arrB = new byte[8];
        // 将原始字节数组转换为8位
        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
            arrB[i] = arrBTmp[i];
        }
        // 生成密钥
        Key key;
        key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
        return key;
    }    
    
    
    /**  
     * 根据密匙进行DES加密  
     *   
     * @param key  
     *            密匙  
     * @param info  
     *            要加密的信息  
     * @return String 加密后的信息  
     */  
    public static String encrypt(Key key, String srcString) throws Exception{   
        // 定义要生成的密文   
        byte[] cipherByte = null;   
        
        // 得到加密/解密器   
        Cipher c1 = Cipher.getInstance(ALGORITHM);   
        // 用指定的密钥和模式初始化Cipher对象   
        // 参数:(ENCRYPT_MODE, DECRYPT_MODE, WRAP_MODE,UNWRAP_MODE)   
        c1.init(Cipher.ENCRYPT_MODE, key);   
        // 对要加密的内容进行编码处理,   
        cipherByte = c1.doFinal(srcString.getBytes());   
        
        // 返回密文的十六进制形式   
        return byte2hex(cipherByte);   
    }   
    
    public static String defaultEncrypt(String srcString) throws Exception{
        return encrypt(getKey(DEFAULT_KEY),srcString);
    }
    
     
    /**  
     * 根据密匙进行DES解密  
     *   
     * @param key  
     *            密匙  
     * @param sInfo  
     *            要解密的密文  
     * @return String 返回解密后信息  
     */  
    public static String decrypt(Key key, String encryptedString) throws Exception{   

        byte[] cipherByte = null;   
        // 得到加密/解密器   
        Cipher c1 = Cipher.getInstance(ALGORITHM);   
        // 用指定的密钥和模式初始化Cipher对象   
        c1.init(Cipher.DECRYPT_MODE, key);   
        // 对要解密的内容进行编码处理   
        cipherByte = c1.doFinal(hex2byte(encryptedString));   
 
        // return byte2hex(cipherByte);   
        return new String(cipherByte);   
    }   
    

    public static String defaultDecrypt(String encryptedString) throws Exception{
        return decrypt(getKey(DEFAULT_KEY),encryptedString);
    }    


    /**  
     * 将二进制转化为16进制字符串  
     *   
     * @param b  
     *            二进制字节数组  
     * @return String  
     */  
    public static String byte2hex(byte[] b) { 
        
        if(null==b){
            return null;
        }
        
        StringBuffer hs = new StringBuffer("");
        String stmp = "";   
        for (int n = 0; n < b.length; n++) {   
            stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));   
            if (stmp.length() == 1) {   
                hs.append("0").append(stmp);
            } else {   
                hs.append(stmp);
            }   
        }   
        return hs.toString().toUpperCase();   
    }   
    /**  
     * 十六进制字符串转化为2进制  
     *   
     * @param hex  
     * @return  
     */  
    public static byte[] hex2byte(String hex) throws Exception {
           if (null== hex || hex.length() % 2 != 0) {
               System.out.println("[ERROR]DESUtil:string to hex is null or invalid length!");
               throw new Exception();
           }
           char[] arr = hex.toCharArray();
           byte[] b = new byte[hex.length() / 2];
           for (int i = 0, j = 0, l = hex.length(); i < l; i++, j++) {
                String swap = "" + arr[i++] + arr[i];
                int byteint = Integer.parseInt(swap, 16) & 0xFF;
                b[j] = new Integer(byteint).byteValue();
           }
           return b;
    } 
    public static void main(String[] args) throws Exception{
        //F7A2744E551B356BC8C758ED4D28F5A0
        //加密
        System.out.println(DesUtils.encrypt(DesUtils.getKey(DEFAULT_KEY),"I LOVE You Chou Lan Lan"));
        //解密
        System.out.println(DesUtils.decrypt(DesUtils.getKey(DEFAULT_KEY),"5A591E309C34621AF7FFDBB429EEE0E18561D84A28B20DB6"));
    }
    
}