There are two different meanings of the term "**", which correspond to physical locks and Wi-Fi networks
Physical locks
In the field of traditional mechanical locks, ** is not a key that can open all locks, but refers to a key that is designed to open multiple locks of the same brand or a specific structural series. By mimicking the common features of standard keys, these keys increase the possibility of matching the internal structure of different cylinders by adding additional teeth or special constructions. However, the security performance of modern locks continues to improve, and there are very few legally produced locks that are truly "illegally manufactured" and are illegal.
In the field of networking, "wifi*** is an application that does not really crack passwords, but is based on information shared by users. When a user connects to a Wi-Fi network using the WiFi*** app, the app records and uploads the network's password and related information to its cloud server. When other users come to the same network coverage area and try to connect to that network, the app looks up the server database to see if there is a password that the user has shared before, and if so, it enables a password-free connection.
To sum up, "*Whether it is at the physical or network level, it is through informal means to achieve the purpose of opening the lock or network without the original key, which may have serious security risks and legal risks in practical applications.