package security;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import javax.crypto.*;

public class SecretData {

  /**
   * 加密函数
   * */
  public String encrypt(SecretKey deskey, String myinfo) {

    try {

      //测试用
      System.out.println("加密前的信息:"+myinfo);
      //加密 测试用
      System.out.println("加密前的二进串:"+byte2hex(myinfo.getBytes()));

      Cipher c1 = Cipher.getInstance("DES");

      //用密钥来加密，方式：加密模式
      c1.init(Cipher.ENCRYPT_MODE,deskey);

      byte[] cipherByte = c1.doFinal(myinfo.getBytes());

      String strAfterEncrypted = byte2hex(cipherByte);

      //测试用
      System.out.println("加密后的二进串:" + strAfterEncrypted);

      return strAfterEncrypted;

    } catch (java.security.NoSuchAlgorithmException e1) {
      e1.printStackTrace();
      return "加密出错";
    } catch (javax.crypto.NoSuchPaddingException e2) {
      e2.printStackTrace();
      return "加密出错";
    } catch (java.lang.Exception e3) {
      e3.printStackTrace();
      return "加密出错";
    }

  }

  /**
   * 解密函数
   * */
  public String decrypt(SecretKey deskey, String secretInfo) {

    try {
      //解密
      Cipher c1 = Cipher.getInstance("DES");

      //用密钥来解密，方式：解密模式
      c1.init(Cipher.DECRYPT_MODE,deskey);

      byte[] clearByte=c1.doFinal(hexToByte(secretInfo));
      String strAfterDecrypt = byte2hex(clearByte);

      //测试用
      System.out.println("解密后的二进串:" + strAfterDecrypt);

      String strAfterInfo = new String(clearByte);

      //测试用
      //System.out.println("解密后的信息:" + strAfterInfo);

      return strAfterInfo;

    } catch (java.security.NoSuchAlgorithmException e1) {
      e1.printStackTrace();
      return "解密出错";
    } catch (javax.crypto.NoSuchPaddingException e2) {
      e2.printStackTrace();
      return "解密出错";
    } catch (java.lang.Exception e3) {
      e3.printStackTrace();
      return "解密出错";
    }

  }

  /**
   *二进制转字符串
   *把二进制数组转换成十六进制串，用：号隔开
   *一个字节（8位）对应于一个两位的十六进制数
  */
  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();

  }

  /**
   * 将十六进制字符串转换成二进制数组
   * */
  public byte[] hexToByte(String c) {

    String strTemp[] = c.split(":");

    byte[] results = new byte[strTemp.length];

    for (int i = 0; i < strTemp.length; i++) {
      results[i] = (byte)(Integer.parseInt(strTemp[i].toLowerCase(), 16));
    }

    return results;

  }

  /**
   * 生成密钥并存入文件OR从文件取出密钥
   * */
  public SecretKey getDeskey() {

    try {

      if ((new File("mykey.dat")).exists() == true) {

        ObjectInputStream in = new ObjectInputStream(new FileInputStream("mykey.dat"));
        SecretKey deskey = (SecretKey)in.readObject();
        in.close();
        return deskey;
      }

      //生成密钥
      KeyGenerator keygen = KeyGenerator.getInstance("DES");
      SecretKey deskey = keygen.generateKey();

      ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("mykey.dat"));

      out.writeObject(deskey);
      out.close();

      System.out.println("写入对象 deskey ok");

      return deskey;
    } catch (java.lang.Exception e) {

      e.printStackTrace();
      System.out.println("生成密钥失败");
      return null;
    }

  }

  /**
   * 该方法测试用
   * */
  public static void main(String[] args) {

    try {

      SecretData my = new SecretData();

      //生成OR取出密钥
      SecretKey deskey = my.getDeskey();

      //加密
      String strForDecrypt = my.encrypt(deskey, "这是加密的信息！");

      System.out.println("deskey is: " + deskey.toString());

      //将strForDecrypt 存到数据库

      System.out.println("从数据库取出来的信息是: " + strForDecrypt);

      //将取出来的deskey 及 strForDecrypt作为参数 来解密
      String strAfterDecryptInfo = my.decrypt(deskey, strForDecrypt);

      System.out.println("解密后的信息是： " + strAfterDecryptInfo);

    } catch (java.lang.Exception e3) {
      e3.printStackTrace();
    }

  }

}

加密前的信息:这是加密的信息！
加密前的二进串5:E2:CA:C7:BC3:C3C:B5:C40:C5:CF:A2:A3:A1
加密后的二进串:0B:8B:2B:ED:3B:78:8B:0C:82:77:F7:65E:E6:C3:75A:EB:0E:B8:AA:6B:27:09
deskey is: com.sun.crypto.provider.DESKey@fffe7ba6
从数据库取出来的信息是: 0B:8B:2B:ED:3B:78:8B:0C:82:77:F7:65E:E6:C3:75A:EB:0E:B8:AA:6B:27:09
解密后的二进串5:E2:CA:C7:BC3:C3C:B5:C40:C5:CF:A2:A3:A1
解密后的信息是： 这是加密的信息！