JAVA DES 学习

 import java.io.IOException; import java.security.SecureRandom; 
 import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; 
 import sun.misc.BASE64Decoder; import sun.misc.BASE64Encoder; 
 public class DesUtil { 
  
    private final static String DES = "DES"; 
  
    public static void main(String[] args) throws Exception { 
        String data = "123 456"; 
        String key = "wang!@#$%"; 
        System.err.println(encrypt(data, key)); 
        System.err.println(decrypt(encrypt(data, key), key)); 
  
    } 
      
    /** 
     * Description 根据键值进行加密 
     * @param data  
     * @param key  加密键byte数组 
     * @return 
     * @throws Exception 
     */
    public static String encrypt(String data, String key) throws Exception { 
        byte[] bt = encrypt(data.getBytes(), key.getBytes()); 
        String strs = new BASE64Encoder().encode(bt); 
        return strs; 
    } 
  
    /** 
     * Description 根据键值进行解密 
     * @param data 
     * @param key  加密键byte数组 
     * @return 
     * @throws IOException 
     * @throws Exception 
     */
    public static String decrypt(String data, String key) throws IOException, 
            Exception { 
        if (data == null) 
            return null; 
        BASE64Decoder decoder = new BASE64Decoder(); 
        byte[] buf = decoder.decodeBuffer(data); 
        byte[] bt = decrypt(buf,key.getBytes()); 
        return new String(bt); 
    } 
  
    /** 
     * Description 根据键值进行加密 
     * @param data 
     * @param key  加密键byte数组 
     * @return 
     * @throws Exception 
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception { 
        // 生成一个可信任的随机数源      
   SecureRandom sr = new SecureRandom(); 
  

        // 从原始密钥数据创建DESKeySpec对象        
 DESKeySpec dks = new DESKeySpec(key); 
  
        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象        
 SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES); 
        SecretKey securekey = keyFactory.generateSecret(dks); 
  
        // Cipher对象实际完成加密操作       
  Cipher cipher = Cipher.getInstance(DES); 
  
        // 用密钥初始化Cipher对象        
 cipher.init(Cipher.ENCRYPT_MODE, securekey, sr); 
  
        return cipher.doFinal(data); 
    } 
      
      
    /** 
     * Description 根据键值进行解密 
     * @param data 
     * @param key  加密键byte数组 
     * @return 
     * @throws Exception 
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception { 
        // 生成一个可信任的随机数源        
 SecureRandom sr = new SecureRandom(); 
  
        // 从原始密钥数据创建DESKeySpec对象         
DESKeySpec dks = new DESKeySpec(key); 
  
        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象     
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES); 
        SecretKey securekey = keyFactory.generateSecret(dks); 
  
        // Cipher对象实际完成解密操作         
Cipher cipher = Cipher.getInstance(DES); 
  
        // 用密钥初始化Cipher对象        
 cipher.init(Cipher.DECRYPT_MODE, securekey, sr); 
  
        return cipher.doFinal(data); 
    } 
}

 转自http://www.oschina.net/code/snippet_727646_18383