一个用DES来加密、解密的类

* 版权所有: 广州点讯科技有限公司 2003

          * Created on 2004-2-24 By Liudong

          */

        

         import java.security.*;

         import javax.crypto.Cipher;

         import javax.crypto.SecretKey;

         import javax.crypto.SecretKeyFactory;

         import javax.crypto.spec.DESKeySpec;

        

         /**

          * 字符串工具集合

          * @author Liudong

          */

         public class StringUtils {

        

           private static final String PASSWORD_CRYPT_KEY = "__jDlog_";

         private final static String DES = "DES";

        

         /**

          * 加密

          * @param src 数据源

          * @param key 密钥，长度必须是8的倍数

          * @return  返回加密后的数据

          * @throws Exception

          */

         public static byte[] encrypt(byte[] src, byte[] key)throws Exception {

                 //DES算法要求有一个可信任的随机数源

                 SecureRandom sr = new SecureRandom();

                 // 从原始密匙数据创建DESKeySpec对象

                 DESKeySpec dks = new DESKeySpec(key);

                 // 创建一个密匙工厂，然后用它把DESKeySpec转换成

                 // 一个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);

                 // 用密匙初始化Cipher对象

                 cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

                 // 现在，获取数据并加密

                 // 正式执行加密操作

                 return cipher.doFinal(src);

              }

        

              /**

              * 解密

              * @param src 数据源

              * @param key 密钥，长度必须是8的倍数

              * @return   返回解密后的原始数据

              * @throws Exception

              */

              public static byte[] decrypt(byte[] src, byte[] key)throws Exception {

                 // DES算法要求有一个可信任的随机数源

                 SecureRandom sr = new SecureRandom();

                 // 从原始密匙数据创建一个DESKeySpec对象

                 DESKeySpec dks = new DESKeySpec(key);

                 // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成

                 // 一个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);

                 // 用密匙初始化Cipher对象

                 cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

                 // 现在，获取数据并解密

                 // 正式执行解密操作

                 return cipher.doFinal(src);

              }

           /**

            * 密码解密

            * @param data

            * @return

            * @throws Exception

            */

           public final static String decrypt(String data){

              try {

               return new String(decrypt(hex2byte(data.getBytes()),

                  PASSWORD_CRYPT_KEY.getBytes()));

             }catch(Exception e) {

             }

             return null;

           }

           /**

            * 密码加密

            * @param password

            * @return

            * @throws Exception

            */

           public final static String encrypt(String password){

             try {

               return byte2hex(encrypt(password.getBytes(),PASSWORD_CRYPT_KEY.getBytes()));
             }catch(Exception e) {

             }

             return null;

           }

         /**

          * 二行制转字符串

          * @param b

          * @return

          */

           public static 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;

                 }

                 return hs.toUpperCase();

            }

           

           public static byte[] hex2byte(byte[] b) {

             if((b.length%2)!=0)

                throw new IllegalArgumentException("长度不是偶数");

                 byte[] b2 = new byte[b.length/2];

                 for (int n = 0; n < b.length; n+=2) {

                   String item = new String(b,n,2);

                   b2[n/2] = (byte)Integer.parseInt(item,16);

                 }

             return b2;