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;
    }