一、aksk生成工具类

public class SignUtil{
    private static final String[] chars = new String[]{"a", "b", "c", "d", "e", "f", "g", "h", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"}

    /**
    * 生成8位app_key
    */
    public static String getAppKey(){
        StringBuffer buffer = new StringBuffer();

        String uuid = UUID.randomUUID().toString().replace("-", "");
        for(int i = 0; i < 8; i++){
            String str = uuid.substring(i * 4, i * 4 + 4);
            int x = Integer.parseInt(str, 16);
            buffer.append(chars[x % 0x3e]);
        }

        return buffer.toString();
    }

    /**
    * 生成24位app_secret
    */
    public static String getAppSecret(String appKey){
        String appSecret = AESUtil.encrypt(appKey, AESUtil.PASSWORD);

        return appSecret;
    }
}

public class AESUtil{
    private static final String ENCODE = "UTF-8";
    private static final String KEY_ALGORITHM = "AES";
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";
    public static final String PASSWORD = "PUPPA%^888";

    /**
    * AES加密
    */
    public static String encrypt(String content, String password){
        try{
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            byte[] byteContent = content.getBytes(ENCODE);
            cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));
            byte[] result = cipher.doFinal(byteContent);

            return new String(Base64.getEncoder().encode(result));
        } catch(Exception ex){
            ex.printStackTrace();
        }

        return null;
    }

    /**
    * AES解密
    */
    public static String decrypt(String content, String password){
        try{
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
            byte[] result =         cipher.doFinal(Base64.getDecoder().decode(content.getBytes()));
            
            return new String(result, ENCODE);
        } catch (Exception ex){
            ex.printStackTrace();
        }

        return null;
    }   

    private static Key getSecretKey(String password) throws NoSuchAlgorithmException{
        KeyGenerator keyGenerator = null;
        // 修改生成密钥的方法
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
        random.setSeed(password.getBytes());
        try{
            keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM);
            // AES要求密钥长度位128
            keyGenerator.init(128, random);
            // 生成一个密钥
            SecretKey secretKey = keyGenerator.generateKey();

            return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);
        } catch (NoSuchAlgorithmException ex){
            ex.printStackTrace();
        }   
        
        return null;
    }
}

二、aksk加密算法

public class SignUtil{
    private static final String SignAlgorithm = "HmacSHA256";

    public static String sign(String secret, String content){
        try{
            Mac mac = Mac.getInstance(SignAlgorithm);
            mac.init(new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), SignAlgorithm));
            String data = BinaryUtil.toHex(hash(content));
            byte[] signByte = mac.doFinal(data.getBytes(StandardCharsets.UTF_8));

            return BinaryUtil.toHex(signByte);
        } catch(NoSuchAlgorithmException | InvalidKeyException ex){
            return null;
        }
    }

    public static byte[] hash(String text){
        try{
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            md.update(text.getBytes(StandardCharsets.UTF_8));

            return md.digest();
        } catch(NoSuchAlgorithmException ex){
            return null;
        }
    }
}

public class BinaryUtil{
    public static String toHex(byte[] data){
        StringBuilder sb = new StringBuilder(data.length * 2)；
        for(byte b : data){
            String hex = Integer.toHexString(b);
            if(hex.length() == 1){
                sb.append("0");
            } else if(hex.length() == 8){
                hex = hex.substring(6);
            }
            sb.append(hex);
        }

        return sb.toString().toLowerCase(Locale.getDefault());
    }
}