加解密

package com.pingan.main;

import java.net.URLDecoder;
import java.net.URLEncoder;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

import org.apache.commons.codec.binary.Base64;

/**
 * DES加密介绍 DES是一种对称加密算法，所谓对称加密算法即：加密和解密使用相同密钥的算法。DES加密算法出自IBM的研究，
 * 后来被美国政府正式采用，之后开始广泛流传，但是近些年使用越来越少，因为DES使用56位密钥，以现代计算能力，
 * 24小时内即可被破解。虽然如此，在某些简单应用中，我们还是可以使用DES加密算法，本文简单讲解DES的JAVA实现 。
 * 注意：DES加密和解密过程中，密钥长度都必须是8的倍数
 */
public class LoginDesUtil {
	public LoginDesUtil() {
	}

	// 测试
	public static void main(String args[]) throws Exception {
		String plaintext = "that is the New game!";
		System.out.println("URLEncode前：" + plaintext);
		String key = "T0FgyDSM";
		plaintext=URLEncoder.encode(plaintext,"UTF-8");
		String ciphertext = LoginDesUtil.encryptDES(plaintext, key);
		System.out.println("明文：" + plaintext);
		System.out.println("密钥：" + key);
		System.out.println("密文：" + ciphertext);
		System.out.println("解密后：" + LoginDesUtil.decryptDES(ciphertext, key));
		System.out.println("URLEncode后：" + URLDecoder.decode(LoginDesUtil.decryptDES(ciphertext, key),"UTF-8"));
	}

	private static byte[] iv = { 1, 4, 7, 8, 5, 2, 6, 3 };

	public static String encryptDES(String encryptString, String encryptKey)
			throws Exception {
		IvParameterSpec zeroIv = new IvParameterSpec(iv);
		SecretKey key = generateKey(encryptKey);
		Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
		cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);
		byte[] encryptedData = cipher.doFinal(encryptString.getBytes());
		return Base64.encodeBase64String(encryptedData);
	}

	public static String decryptDES(String decryptString, String decryptKey)
			throws Exception {
		byte[] byteMi = Base64.decodeBase64(decryptString);
		IvParameterSpec zeroIv = new IvParameterSpec(iv);
		SecretKey key = generateKey(decryptKey);
		Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
		cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);
		byte decryptedData[] = cipher.doFinal(byteMi);

		return new String(decryptedData);
	}
	
	public static SecretKey generateKey(String secretKey) throws NoSuchAlgorithmException{  
		KeyGenerator _generator = KeyGenerator.getInstance("DES");  
        //防止linux下 随机生成key   
        SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" );  
        secureRandom.setSeed(secretKey.getBytes());  
          
        _generator.init(56,secureRandom);  
	      
	    // 生成密钥  
	    return _generator.generateKey();  
	} 
}