import javax.crypto.Cipher;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.DESKeySpec;

import javax.crypto.spec.IvParameterSpec;

import java.security.Key;

import java.text.SimpleDateFormat;

import java.util.Base64;

import java.util.Date;

public class DESUtil {

    /**

     * 偏移变量，固定占8位字节

     */

    private final static String IV_PARAMETER = "12345678";

    /**

     * 密钥算法

     */

    private static final String ALGORITHM = "DES";

    /**

     * 加密/解密算法-工作模式-填充模式

     */

    private static final String CIPHER_ALGORITHM = "DES/CBC/PKCS5Padding";

    /**

     * 默认编码

     */

    private static final String CHARSET = "utf-8";

    private static  SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");

    /**

     * 生成key

     *

     * @param password

     * @return

     * @throws Exception

     */

    private static Key generateKey(String password) throws Exception {

        DESKeySpec dks = new DESKeySpec(password.getBytes(CHARSET));

        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);

        return keyFactory.generateSecret(dks);

    }

    /**

     * DES加密字符串

     *

     * @param password 加密密码，长度不能够小于8位

     * @param data 待加密字符串

     * @return 加密后内容

     */

    public static String encrypt(String password, String data) {

        if (password== null || password.length() < 8) {

            throw new RuntimeException("加密失败，key不能小于8位");

        }

        if (data == null)

            return null;

        try {

            Key secretKey = generateKey(password);

            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);

            IvParameterSpec iv = new IvParameterSpec(IV_PARAMETER.getBytes(CHARSET));

            cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);

            byte[] bytes = cipher.doFinal(data.getBytes(CHARSET));

            //JDK1.8及以上可直接使用Base64，JDK1.7及以下可以使用BASE64Encoder

            //Android平台可以使用android.util.Base64

            return new String(Base64.getEncoder().encode(bytes));

        } catch (Exception e) {

            e.printStackTrace();

            return data;

        }

    }

    /**

     * DES解密字符串

     *

     * @param password 解密密码，长度不能够小于8位

     * @param data 待解密字符串

     * @return 解密后内容

     */

    public static String decrypt(String password, String data) {

        if (password== null || password.length() < 8) {

            throw new RuntimeException("加密失败，key不能小于8位");

        }

        if (data == null)

            return null;

        try {

            Key secretKey = generateKey(password);

            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);

            IvParameterSpec iv = new IvParameterSpec(IV_PARAMETER.getBytes(CHARSET));

            cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);

            return new String(cipher.doFinal(Base64.getDecoder().decode(data.getBytes(CHARSET))), CHARSET);

        } catch (Exception e) {

            e.printStackTrace();

            return data;

        }

    }

    /**

     * 解密

     * @param data

     * @return

     */

    public static String  decryptionKey(String data){

        String format = sdf.format(new Date());

        String decrypt = decrypt(format,data);

        return decrypt;

    }

    /**

     * 加密

     * @param data

     * @return

     */

    public static String  encryptionKey(String data){

        String format = sdf.format(new Date());

        String encrypt = encrypt(format,data);

        return encrypt;

    }

    public static void main(String[] args) {

        System.out.println(encryptionKey("100"));

    }

}