package lsy;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class DesUtil {
 /**
  * @param args
  */
 public static void main(String[] args) {
  //以下是加密方法algorithm="AES"的測試
  System.out.println(DesUtil.getInstance("lushuaiyin").getEnCodeString("hello"));
  //輸出 LDewGAZkmWHeYFjBz56ylw==
  //將上面的密文解密：
  System.out.println(DesUtil.getInstance("lushuaiyin").getDecodeString("LDewGAZkmWHeYFjBz56ylw=="));
  //輸出 hello
  //改變密鑰測試
  System.out.println(DesUtil.getInstance("suolong").getEnCodeString("hello"));
  //輸出 /RLowOJ+Fr3KdMcdJeNatg==
  System.out.println(DesUtil.getInstance("suolong").getDecodeString("/RLowOJ+Fr3KdMcdJeNatg=="));
  //輸出 hello
  //如果使用不正確的密鑰解密，將會：
  System.out.println(DesUtil.getInstance("suolong").getDecodeString("LDewGAZkmWHeYFjBz56ylw=="));
 }
 private SecretKey key=null;//密鑰
 //定義 加密算法,可用 DES,DESede,Blowfish,AES
 //不同的加密方式結果會不同
 private static String algorithm="AES";
 private static DesUtil desUtil=null;
 public DesUtil(){}
 public static DesUtil getInstance(String strKey){
  desUtil=new DesUtil();
  desUtil.createKey(strKey);
  return desUtil;
 }
 /**
  * algorithm 算法
  * @param strKey
  */
 public void createKey(String strKey){
  try{
   KeyGenerator kg=KeyGenerator.getInstance(DesUtil.algorithm);
   byte[] bt=strKey.getBytes("UTF-8");
   SecureRandom sr=new SecureRandom(bt);
   kg.init(sr);
   this.setKey(kg.generateKey());
  }catch(Exception e){
  }
 }
 /**
  * 加密方法，返回密文
  * cipher 密碼
  * @param dataStr
  */
 public String getEnCodeString(String dataStr){
  byte[] miwen=null;//密文
  byte[] mingwen=null;//明文
  Cipher cipher;
  String result="";//密文字符串
  try{
   mingwen=dataStr.getBytes("UTF-8");
   cipher=Cipher.getInstance(DesUtil.algorithm);
   cipher.init(Cipher.ENCRYPT_MODE, this.getKey());
   miwen=cipher.doFinal(mingwen);
   BASE64Encoder base64en = new BASE64Encoder();
   result=base64en.encodeBuffer(miwen);//或者可以用下面的方法得到密文，結果是不一樣的，都可以正常解密
//   result=byte2hex(miwen);//密文結果類似2C:37:B0:18:06:64:99:61:DE:60:58:C1:CF:9E:B2:97
  }catch(Exception e){
   e.printStackTrace();
  }
  return result;
 }
 /**
  * 解密方法，返回明文
  * @param codeStr
  * @return
  */
 public String getDecodeString(String codeStr){
  BASE64Decoder base64De = new BASE64Decoder();
  byte[] miwen=null;
  byte[] mingwen=null;
  String resultData="";//返回的明文
  Cipher cipher;
  try{
   miwen=base64De.decodeBuffer(codeStr);
   cipher=Cipher.getInstance(DesUtil.algorithm);
   cipher.init(Cipher.DECRYPT_MODE, this.getKey());
   mingwen=cipher.doFinal(miwen);
   resultData = new String(mingwen,"UTF-8");
  }catch(Exception e){
   return "密鑰不正確或其他原因導致異常，無法解密！";
  }
  return resultData;
 }
  //二行制轉字符串
 public String byte2hex(byte[] b) {
  String hs = "";
  String stmp = "";
  for (int n = 0; n < b.length; n++) {
   stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
   if (stmp.length() == 1)
    hs = hs + "0" + stmp;
   else
    hs = hs + stmp;
   if (n < b.length - 1)
    hs = hs + ":";
  }
  return hs.toUpperCase();
 }
 public SecretKey getKey() {
  return key;
 }
 public void setKey(SecretKey key) {
  this.key = key;
 }
 public static String getAlgorithm() {
  return algorithm;
 }
 public static void setAlgorithm(String algorithm) {
  algorithm = algorithm;
 }
}

LDewGAZkmWHeYFjBz56ylw==
hello
/RLowOJ+Fr3KdMcdJeNatg==
hello
密鑰不正確或其他原因導致異常，無法解密！