public class Sm4 {


    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    private static final String ENCODING = "UTF-8";
    public static final String ALGORITHM_NAME = "SM4";
    // 加密算法/分组加密模式/分组填充方式
    // PKCS5Padding-以8个字节为一组进行分组加密
    // 定义分组加密模式使用：PKCS5Padding
    public static final String ALGORITHM_NAME_ECB_PADDING = "SM4/ECB/PKCS5Padding";
    // 128-32位16进制；256-64位16进制
    public static final int DEFAULT_KEY_SIZE = 128;

    /**
     * 自动生成密钥
     *
     * @return
     * @explain
     */
    public static String generateKey() throws Exception {
        return new String(Hex.encodeHex(generateKey(DEFAULT_KEY_SIZE),false));
    }

    /**
     * @param keySize
     * @return
     * @throws Exception
     * @explain
     */
    public static byte[] generateKey(int keySize) throws Exception {
        KeyGenerator kg = KeyGenerator.getInstance(ALGORITHM_NAME, BouncyCastleProvider.PROVIDER_NAME);
        kg.init(keySize, new SecureRandom());
        return kg.generateKey().getEncoded();
    }

    /**
     * 生成ECB暗号
     *
     * @param algorithmName 算法名称
     * @param mode          模式
     * @param key
     * @return
     * @throws Exception
     * @explain ECB模式（电子密码本模式：Electronic codebook）
     */
    private static Cipher generateEcbCipher(String algorithmName, int mode, byte[] key) throws Exception {
        Cipher cipher = Cipher.getInstance(algorithmName, BouncyCastleProvider.PROVIDER_NAME);
        Key sm4Key = new SecretKeySpec(key, ALGORITHM_NAME);
        cipher.init(mode, sm4Key);
        return cipher;
    }

    /**
     * sm4加密
     *
     * @param hexKey   16进制密钥（忽略大小写）
     * @param paramStr 待加密字符串
     * @return 返回16进制的加密字符串
     * @explain 加密模式：ECB
     * 密文长度不固定，会随着被加密字符串长度的变化而变化
     */
    public static String encryptEcb(String hexKey, String paramStr) {
        try {
            String cipherText = "";
            // 16进制字符串-->byte[]
            byte[] keyData = ByteUtils.fromHexString(hexKey);
            // String-->byte[]
            byte[] srcData = paramStr.getBytes(ENCODING);
            // 加密后的数组
            byte[] cipherArray = encrypt_Ecb_Padding(keyData, srcData);
            // byte[]-->hexString
            cipherText = ByteUtils.toHexString(cipherArray);
            return cipherText;
        } catch (Exception e) {
            return paramStr;
        }
    }

    /**
     * 加密模式之Ecb
     *
     * @param key
     * @param data
     * @return
     * @throws Exception
     * @explain
     */
    public static byte[] encrypt_Ecb_Padding(byte[] key, byte[] data) throws Exception {
        Cipher cipher = generateEcbCipher(ALGORITHM_NAME_ECB_PADDING, Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * sm4解密
     *
     * @param hexKey     16进制密钥
     * @param cipherText 16进制的加密字符串（忽略大小写）
     * @return 解密后的字符串
     * @throws Exception
     * @explain 解密模式：采用ECB
     */
    public static String decryptEcb(String hexKey, String cipherText) {
        // 用于接收解密后的字符串
        String decryptStr = "";
        // hexString-->byte[]
        byte[] keyData = ByteUtils.fromHexString(hexKey);
        // hexString-->byte[]
        byte[] cipherData = ByteUtils.fromHexString(cipherText);
        // 解密
        byte[] srcData = new byte[0];
        try {
            srcData = decrypt_Ecb_Padding(keyData, cipherData);
            // byte[]-->String
            decryptStr = new String(srcData, ENCODING);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return decryptStr;
    }

    /**
     * 解密
     *
     * @param key
     * @param cipherText
     * @return
     * @throws Exception
     * @explain
     */
    public static byte[] decrypt_Ecb_Padding(byte[] key, byte[] cipherText) throws Exception {
        Cipher cipher = generateEcbCipher(ALGORITHM_NAME_ECB_PADDING, Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(cipherText);
    }

    /**
     * 校验加密前后的字符串是否为同一数据
     *
     * @param hexKey     16进制密钥（忽略大小写）
     * @param cipherText 16进制加密后的字符串
     * @param paramStr   加密前的字符串
     * @return 是否为同一数据
     * @throws Exception
     * @explain
     */
    public static boolean verifyEcb(String hexKey, String cipherText, String paramStr) throws Exception {
        // 用于接收校验结果
        boolean flag = false;
        // hexString-->byte[]
        byte[] keyData = ByteUtils.fromHexString(hexKey);
        // 将16进制字符串转换成数组
        byte[] cipherData = ByteUtils.fromHexString(cipherText);
        // 解密
        byte[] decryptData = decrypt_Ecb_Padding(keyData, cipherData);
        // 将原字符串转换成byte[]
        byte[] srcData = paramStr.getBytes(ENCODING);
        // 判断2个数组是否一致
        flag = Arrays.equals(decryptData, srcData);
        return flag;
    }


    public static void main(String[] args) {

        String key = "74d32aad624c62be6f774648530af79e";

        String cipher = "hello world";

        try {

            String enStr = Sm4Util.encryptEcb(key, cipher);
            System.out.println(enStr);

            String json = Sm4Util.decryptEcb(key, enStr);
            System.out.println(json);


        } catch (Exception exception) {
            exception.printStackTrace();
        }

    }


}