US Patent 6975202 Electronic key system, apparatus and method

A system, apparatus and method for using an electronic key to open electronic locking devices is provided. With the system, apparatus and method, a key code is sent to a user's wireless communication device and is later used to open a corresponding locking device. The key code is generated by a key supplier based on a master key obtained from a master key supplier, e.g. an electronic lock manufacturer. The key code may include a master key portion, a secondary key portion, an activation/expiration portion, a wireless device identifier portion, a time of issue portion, and a time of last use portion.