Methods and apparatus for controlling access to secure areas are described. Time varying values are generated from access device identifiers, e.g., door identifiers. The time varying value, e.g., a hashed door identifier value, is transmitted as a VLC signal by a luminaire near the door to which the hashed identifier corresponds. A mobile detects the transmitted hashed door identifier value and sends an access request via a wireless signal, e.g., a radio signal. The access request includes a value generated from the received hashed door identifier and a mobile device identifier. A control device determines, from information in the access request and stored information indicating which mobile devices have authority to access which doors, if access should be granted to the door corresponding to the hashed access device identifier from which the received information was generated. The received information may be hash of the mobile identifier and hashed door identifier.