the passive electronic lock and also records the time of unlocking the passive electronic lock. Passive electronic locks can only be unlocked by a key with unlocking authority, and unlocking will fail if there is no unlocking authority. Passive electronic locks are currently used in a number of specialized fields, such as power utilities, water utilities, public safety, transportation, data centers, etc. Programmable lock The programmable electronic lock system is realized by programmable keys, electronic locks and software. When the identification code of the key matches the identification code of the lock, all available keys are operated to unlock. The internal structure of the lock contains a cylinder, which has a contact (lock slot) that is in contact with the key, and a part of it is an electronic control device to store and verify the received identification code and respond (whether it is unlocked). The key contains a power supply device, usually a rechargeable battery or a replaceable battery in the key, used to drive the system to work; it also includes an electronic storage and control device for storing the identification code of the lock. The software is used to set and modify the data of each key and lock. Using this type of key and lock control system does not need to change user habits. In addition, compared with the previous mechanical device, its advantage is that only one key can open multiple locks instead of a bunch of keys like the current one. A single key can contain many lock identification codes; which can set the unlock permission for a single user. Authentication methods A feature of electronic locks is that the locks can deactivated or opened by authentication, without the use of a traditional physical key: Numerical codes, passwords, and passphrases Perhaps the most common form of electronic lock uses a keypad to enter a numerical code or password for authentication. Some feature an audible response to each press. Combination lengths are usually between four and six digits long. Security tokens Another means of authenticating users is to require them to scan or "swipe" a security token such as a smart card or similar, or to interact a token with the lock. For example, some locks can access stored credentials on a personal digital assistant (PDA) or smartphone, by using infrared, Bluetooth, or NFC data transfer methods. Biometrics As biometrics become more and more prominent