java实现重要信息的加密解密(模拟信用卡号的保存)

package cn.felay.io;

import java.io.Externalizable;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.ObjectInput;

import java.io.ObjectInputStream;

import java.io.ObjectOutput;

import java.io.ObjectOutputStream;

import java.security.InvalidKeyException;

import javax.crypto.BadPaddingException;

import javax.crypto.Cipher;

import javax.crypto.IllegalBlockSizeException;

import javax.crypto.KeyGenerator;

import javax.crypto.spec.SecretKeySpec;

/**

* 自定义序列化对象信息(加密保存重要信息)

*

* @author felayman

* @timer 2014年6月10日 下午8:10:29

*/

public class ExternalizableDemo {

public static void main(String[] args) {

Customer customer;

try {

// 构造一个信用卡用户

customer = new Customer(1, "1234-5678-9876");

// 打印加密前的信用卡信息

System.out.println("before saving object:");

System.out.println("ID:" + customer.getId() + ",CC:"

+ customer.getCreditCard());

// 创建对象输出流,该流是给予文件输出流的,即该流的数据是从文件中获取的,下面两行代码表示创建一个写入到指定文件的对象输出流

ObjectOutputStream outStream = new ObjectOutputStream(

new FileOutputStream("src/res/customer.dat"));

// 将创建号的信用卡用户保存到customer.dat文件中

outStream.writeObject(customer);

outStream.close();// 关闭流

// 创建一个从指定文件读取内容的输入流

ObjectInputStream inputStream = new ObjectInputStream(

new FileInputStream("src/res/customer.dat"));

// 将读取的对象保存到

customer = (Customer) inputStream.readObject();

System.out.println("after retreieving object");// 输出解密后的对象信息

System.out.println("ID:" + customer.getId() + ",CC:"

+ customer.getCreditCard());

inputStream.close();

} catch (IOException e) {

e.printStackTrace();

} catch (ClassNotFoundException e) {

e.printStackTrace();

}

}

}

class Customer implements Externalizable {

private int id; // ID号

private String creditCard; // 信用卡号

private static Cipher cipher; // 加密和解密

private static SecretKeySpec secretKeySpec; // 密钥

public Customer() {

this.id = 0;

this.creditCard = "";

}

// 该实例保存用户的id号和信用卡号

public Customer(int id, String creditCard) {

this.id = id;

this.creditCard = creditCard;

}

static {

try {

createCipher(); // 创建一个加密解密机

} catch (Exception e) {

e.printStackTrace();

System.out.println("加密过程出现错误");

System.exit(1);

}

}

public int getId() {

return this.id;

}

private static void createCipher() throws Exception {

KeyGenerator kgen = KeyGenerator.getInstance("AES");// Rijndael加密算法

kgen.init(128); // 指定生成的密钥长度为128位

SecretKeySpec skey = (SecretKeySpec) kgen.generateKey();// 根据Rijndael加密算法生成一个密钥,并将密钥以字节数组方式保存到SecretKeySpec对象中

byte[] raw = skey.getEncoded();// 将生成的密钥保存到字节数组中

secretKeySpec = new SecretKeySpec(raw, "AES");// 密钥转换,将上述的密钥保存到Customer类的属性中,防止失效

cipher = Cipher.getInstance("AES");// 将算法密钥保存到该对象中以实现解密功能

}

public String getCreditCard() {

return this.creditCard;

}

public static Cipher getCipher() {

return cipher;

}

public static SecretKeySpec getSecretKeySpec() {

return secretKeySpec;

}

// 保存密钥

@Override

public void writeExternal(ObjectOutput out) throws IOException {

try {

out.write(this.id);

this.encript();

out.writeUTF(this.creditCard);

System.out.println("after encryption:");// 加密后

System.out.println("id:" + this.id + ",CC:" + this.creditCard);

} catch (InvalidKeyException | IllegalBlockSizeException

| BadPaddingException e) {

e.printStackTrace();

}

}

// 读取密钥

@Override

public void readExternal(ObjectInput in) throws IOException,

ClassNotFoundException {

this.id = in.read();

String str = in.readUTF();

this.decrypt(str);

}

// 加密

private void encript() throws InvalidKeyException,

IllegalBlockSizeException, BadPaddingException {

cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

byte[] buff = cipher.doFinal(this.creditCard.getBytes());

this.creditCard = new String(buff);

}

// 解密

private void decrypt(String str) {

try {

cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);

byte[] buff = cipher.doFinal(str.getBytes());

this.creditCard = new String(buff);

} catch (InvalidKeyException | IllegalBlockSizeException

| BadPaddingException e) {

e.printStackTrace();

}

}

}