Access Control and Zones
Access control answers one question at every boundary: are you who you claim to be, and are you allowed past this line right now? A badge proves possession. A PIN proves knowledge. A fingerprint proves identity. Stack them and you defeat the theft of any one factor. But identity is only half the control; authorization is the other half. A valid badge that opens a door it should never open is a policy failure, not a technology failure. The strongest access system enforces least privilege at every ring, logs every transaction, and assumes every credential will eventually be lost, cloned, or coerced.
Knowledge check
What does a mantrap or access-controlled airlock defend against that a single locked door cannot?
Show the answer
It defeats tailgating and piggybacking by permitting only one authenticated person through at a time. The interlocked doors trap a person in a controlled vestibule until they authenticate, so a second person cannot slip through on someone else's credential, and it enforces one-badge-one-body accountability.