Learn in the textbookPhysical Security Measures
DefinitionEntry/exit management authenticates anyone trying to enter a room, lets in only those permitted, and logs their comings and goings.
ExplanationIdentity is checked with an IC card, a PIN, biometrics and so on, and the decision is logged together with who came in or out and when. It is often combined with zoning (ゾーニング), which divides the premises into areas by how sensitive their information is, so that each area admits a different set of people. On the other hand, tailgating (共連れ), where someone slips in behind an authenticated person without authenticating, is hard to stop with authentication at the door alone.
AnalogyIt resembles hotel key cards. Each card opens only certain rooms, and unlike an ordinary key, the system knows which card opened the door.
Memory hookThe Japanese name contains both 入 (enter) and 退 (leave). Only by logging exits as well can you tell who is in the room right now.