DES加密(一)

import cn.eaglelink.module.base.other.MessageEncrypt;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import org.apache.log4j.Logger;

/**
 * DES加密算法来加密消息xml字符串
 * @author song.li
 *
 */
public class DESEncryptMessage implements MessageEncrypt {
 private static Logger logger = Logger.getLogger(DESEncryptMessage.class); 
// private Key key;
 /**
 * 根据参数生成KEY
 * @param strKey
 */
 public void saveDesKey(String strKey) {
  logger.debug("进入创建DES密钥方法...");
  Key key;
  try{
   KeyGenerator _generator = KeyGenerator.getInstance("DES");
   _generator.init(new SecureRandom(strKey.getBytes()));
   //生成密钥
   key = _generator.generateKey();
   _generator=null;
   //将密钥保存到文件中
   FileOutputStream fos = new FileOutputStream("d:/DesKey.xml");
   ObjectOutputStream oos = new ObjectOutputStream(fos);
   oos.writeObject(key);
   oos.close();   
  }catch(Exception e){
   logger.error("创建DES密钥失败！");
  }
 }
 
 /**
  *获得DES加密的密钥。在交易处理的过程中应该定时更换密钥。
  * @return kp
  */
 public static Key getKey() {
  logger.debug("进入取得DES密钥方法...");
  Key kp = null;
  try {
  String fileName = "DesKey.xml";
  InputStream is = DESEncryptMessage.class.getClassLoader().getResourceAsStream(fileName);
  ObjectInputStream oos = new ObjectInputStream(is);
  kp = (Key) oos.readObject();
  oos.close();
  }catch(Exception e){
   logger.error("取得DES密钥失败！");
  }
  return kp;
 }

 
 /**
 * 加密String明文输入,String密文输出
 * @param messageXml
 * @return
 */
 @Override
 public String encryptMessage(String messageXml) {
  logger.debug("进入DES加密的主方法...");
  //具体实现DES加密算法来实现消息xml的加密
  byte[] byteMi = null;
  byte[] byteMing = null;
  String strMi = "";
  try {
   return byte2hex(getEncCode (messageXml.getBytes() ) );

  // byteMing = strMing.getBytes("UTF8");
  // byteMi = this.getEncCode(byteMing);
  // strMi = new String( byteMi,"UTF8");
  }catch(Exception e){
   logger.error("使用DES算法将xml字符串加密失败！");
  }finally{
   byteMing = null;
   byteMi = null;
  }
  return strMi; 
 }
 
 /**
 * 加密以byte[]明文输入,byte[]密文输出
 * @param byteS
 * @return
 */
 private byte[] getEncCode(byte[] byteS) {
  logger.debug("进入DES加密以byte[]明文输入,byte[]密文输出方法...");
  byte[] byteFina = null;
  Cipher cipher;
  try {
   cipher = Cipher.getInstance("DES");
   cipher.init(Cipher.ENCRYPT_MODE, getKey());
   byteFina = cipher.doFinal(byteS);
  }catch(Exception e) {
   logger.error("DES加密以byte[]明文输入,byte[]密文输出失败！");
  }finally {
   cipher = null;
  }
  return byteFina;
 }
 
 /**
 * 二行制转字符串
 * @param b
 * @return
 */
 public static String byte2hex(byte[] b) { //一个字节的数，
  logger.debug("进入二行制转字符串方法...");
  // 转成16进制字符串
  String hs = "";
  String stmp = "";
  for (int n = 0; n < b.length; n++) {
   //整数转成十六进制表示
   stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
   if (stmp.length() == 1){
    hs = hs + "0" + stmp;
   }else{
    hs = hs + stmp;
   }   
  }
  return hs.toUpperCase(); //转成大写
 }
 
 /**
 * 解密 以String密文输入,String明文输出
 * @param strMi
 * @return
 */
 public String getDesString(String strMi) {
  byte[] byteMing = null;
  byte[] byteMi = null;
  String strMing = "";
  try {
   return new String(getDesCode(hex2byte(strMi.getBytes()) ));
 
  // byteMing = this.getDesCode(byteMi);
  // strMing = new String(byteMing,"UTF8");
  }catch(Exception e) {
   e.printStackTrace();
  }finally {
   byteMing = null;
   byteMi = null;
  }
  return strMing;
 }
 
 /**
 * 解密以byte[]密文输入,以byte[]明文输出
 * @param byteD
 * @return
 */
 private byte[] getDesCode(byte[] byteD) {
  Cipher cipher;
  byte[] byteFina=null;
  try{
   cipher = Cipher.getInstance("DES");
   cipher.init(Cipher.DECRYPT_MODE, getKey());
   byteFina = cipher.doFinal(byteD);
  }catch(Exception e){
   e.printStackTrace();
  }finally{
   cipher=null;
  }
  return byteFina;
 }
 
 public static byte[] hex2byte(byte[] b) {
  if((b.length%2)!=0)
  throw new IllegalArgumentException("长度不是偶数");
  byte[] b2 = new byte[b.length/2];
  for (int n = 0; n < b.length; n+=2) {
   String item = new String(b,n,2);
   // 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个进制字节
   b2[n/2] = (byte)Integer.parseInt(item,16);
  }
  return b2;
 }
 
 public static void main(String[] args) {
  DESEncryptMessage des=new DESEncryptMessage();//实例化一个对像
  des.saveDesKey("aadd");//生成密匙
  String result=des.encryptMessage("helloworld");
  System.out.println("生成的密文为－－result="+result);
  String result2=des.getDesString(result);
  System.out.println("解密后的原文为－－result="+result2);
 }
}