key.java

一个用于实现不同数据库数据同步的程序

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.SecureRandom;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.io.*;
import java.util.*;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class Key
{

	private String keyAddress;

	Key(String ka)
	{
		keyAddress = ka+"key.txt";
	}

	public void createKey() throws Exception
	{
		SecureRandom sr = new SecureRandom();
		KeyGenerator kg = KeyGenerator.getInstance("DES");
		kg.init(sr);
		SecretKey key = kg.generateKey();
		byte data[] = key.getEncoded();
		FileOutputStream fo = new FileOutputStream(new File(keyAddress));
		fo.write(data);
	}

	public void encryption(String t)
	{
		SecureRandom sr = new SecureRandom();
		FileInputStream fi = null;
		byte data[] = null;
		File file = null;

		try
		{
			// 获得密匙数据
			file = new File(keyAddress);
			fi = new FileInputStream(file);
			data = new byte[fi.available()];
			fi.read(data);
			fi.close();
		}
		catch(Exception e){}

		// 从原始密匙数据创建DESKeySpec对象
		DESKeySpec dks = null;
		// 创建一个密匙工厂，然后用它把DESKeySpec转换成一个SecretKey对象
		SecretKey key = null;
		// Cipher对象实际完成加密操作
		Cipher cipher = null;

		try
		{
			dks = new DESKeySpec(data);
			key = SecretKeyFactory.getInstance("DES").generateSecret(dks);
			cipher = Cipher.getInstance("DES");
			// 用密匙初始化Cipher对象
			cipher.init(Cipher.ENCRYPT_MODE, key, sr);
		}
		catch(Exception e){}
	
		// 获取要加密的文件数据
		try
		{
			file = new File(t);
			fi = new FileInputStream(file);
			data = new byte[fi.available()];
			fi.read(data);
			fi.close();
		}
		catch(Exception e){}

		// 正式执行加密操作
		FileOutputStream fo = null;
		try
		{
			data = cipher.doFinal(data);
			// 用加密后的数据覆盖原文件
			fo = new FileOutputStream(file);
			fo.write(data);
			fo.close();
		}
		catch(Exception e){}

	}

	public void decrypt(String t)
	{
		SecureRandom sr = new SecureRandom();
		FileInputStream fi = null;
		File file = null;
		byte data[] = null;

		// 获得密匙数据
		try
		{
			file = new File(keyAddress);
			fi = new FileInputStream(file);
			data = new byte[fi.available()];
			fi.read(data);
			fi.close();
		}
		catch(Exception e){}

		// 从原始密匙数据创建一个DESKeySpec对象
		DESKeySpec dks = null;
		// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成一个SecretKey对象
		SecretKey key = null;
		// Cipher对象实际完成解密操作
		Cipher cipher = null;
		try
		{
			dks = new DESKeySpec(data);
			key = SecretKeyFactory.getInstance("DES").generateSecret(dks);
			cipher = Cipher.getInstance("DES");
			// 用密匙初始化Cipher对象
			cipher.init(Cipher.DECRYPT_MODE, key, sr);
			// 现在，获取数据并解密
			file=new File(t);
			fi = new FileInputStream(file);
			data = new byte[fi.available()];
			fi.read(data);
			fi.close();
		}
		catch(Exception e){}

		// 正式执行解密操作
		FileOutputStream fo = null;
		try
		{
			data = cipher.doFinal(data);
			// 把数据还原成原有的类文件
			fo = new FileOutputStream(file);
			fo.write(data);
		}
		catch(Exception e){}
	}

	/*public static void main(String[] args)
	{
		Key k=null;
		try
					{
						k=new Key("d:\\");
						k.createKey();
						k.encryption("d:\\a.txt");
		k.decrypt("d:\\a.txt");
					}
					catch (Exception e)
					{
						e.printStackTrace();
					}
	}*/

}