import java.security.SecureRandom;  import javax.crypto.Cipher;  import javax.crypto.SecretKey;  import javax.crypto.SecretKeyFactory;  import javax.crypto.spec.DESKeySpec;      public class CryptKit {          private final static String DES = "DES";          public static void main(String args[]) throws Exception {          String str = encrypt("The cold night", "12345678");          System.out.println(str);          String str2 = decrypt("63B121C4EA212F8BC74E8113BDFBFB81", "12345678");          System.out.println(str2);      }          // 加密      public static byte[] encrypt(byte[] data, byte[] key) throws Exception {          Cipher cipher = Cipher.getInstance(DES);          DESKeySpec ds = new DESKeySpec(key);          SecureRandom sr = new SecureRandom();          SecretKeyFactory skfactory = SecretKeyFactory.getInstance(DES);          SecretKey skey = skfactory.generateSecret(ds);          cipher.init(Cipher.ENCRYPT_MODE, skey, sr);          byte[] b = cipher.doFinal(data);          return b;      }          // 加密      public static String encrypt(String data, String key) throws Exception {          return byte2hex(encrypt(data.getBytes(), key.getBytes()));      }          // 解密      public static byte[] decrypt(byte[] data, byte[] key) throws Exception {          Cipher cipher = Cipher.getInstance(DES);          DESKeySpec ds = new DESKeySpec(key);          SecureRandom sr = new SecureRandom();          SecretKeyFactory skfactory = SecretKeyFactory.getInstance(DES);          SecretKey skey = skfactory.generateSecret(ds);          cipher.init(Cipher.DECRYPT_MODE, skey, sr);          return cipher.doFinal(data);      }          // 解密      public static String decrypt(String data, String key) throws Exception {          return new String(decrypt(hex2byte(data.getBytes()), key.getBytes()));      }          private static String byte2hex(byte[] b) {          StringBuilder hs = new StringBuilder();          String stmp;          for (int n = 0; b != null && n < b.length; n++) {              stmp = Integer.toHexString(b[n] & 0XFF);              if (stmp.length() == 1)                  hs.append('0');              hs.append(stmp);          }          return hs.toString().toUpperCase();      }          private static byte[] hex2byte(byte[] b) {          if ((b.length % 2) != 0)              throw new IllegalArgumentException();          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;      }