I have received inquiries regarding my Datacenter Physical Security Blueprint . The questions were about the deadman door and how one works. So, here is a short definition, functional specifications and a blueprint of a dead-man door
A dead-man door is a high security access portal. For a movie representation of the deadman door, i refer you to Sneakers ("My name is Werner Brandes. My voice is my password. Verify me") The idea is to have two separate authentication processes, with the second one being performed while the authenticated person is 'trapped' inside a reinforced enclosure.
The second authentication is made against several biometric attributes of the person which are stored in a database, and always include weight measurement, thus preventing a second person 'piggybacking' with the first person.
I recommend a retina scan and weight measurement, since a fingerprint is very easy to fool - even seen on Mythbusters
Functional specification of a dead-man door
For the purpose of the specification, the doors of the dead-man door will be named:
- inside door - connecting the deadman door to the highly secure area
- outside door - connecting the deadman door to the rest of the facility
- The deadman door should comfortably accommodate 1 person
- The entire floor of the dead-man door should be connected to a scale sensors for weight measurement
- The inside wall surfaces of the deadman door should be smooth and not have any ledges which may be used to trick the scale by supporting oneself on them
- Both doors of the deadman door must open outward from the door enclosure.
- Doors should be bulletproof, and at least 50% of the door surfaces should be bulletproof glass - preferably standard EN1522, class FB2 or higher (stopping a 9mm Luger fired at 5 m). Both doors should be equipped with door closer to close the door without human intervention
- Both doors of the deadman door must be equipped with electronic locks controlled by a common controller. All electronic locks should have a mechanical lock override for emergency conditions. Both doors of the deadman door must be equipped with minimum two open-door sensors. (for redundancy)
- When entering the dead-man door, each door should open under the following conditions - approved authentication (key card or key card + pin keypad) and other door lock is locked and there are no open door sensor alerts on the other door.
- The person inside the dead-man door should have a selector to indicate in which direction he will go (which door to unlock)
- When inside the deadman door, each door should open only under the following conditions - the other door is locked and there are no open door sensor alerts on the other door; approved biometric authentication and weight of authenticated person is within acceptable variation of database value - biometric authentication should always authenticate to the parameters of the person whose key card was used to enter the dead man door.
- A mechanical override (unlock) of any door should always raise a silent alarm - regardless of conditions. All sensors and authentication mechanisms of the dead-man door should be connected to a central monitoring and alarm system, and each non-normal event should raise at least a silent alarm and lock the deadman door.
A dead man door is a very powerful system access control system, but can be very dangerous if panic conditions are not taken into account.
- Automatic controls - a predefined timer for passing through a dead-man door must be set-up. If within that time the second door does not open and close, an immediate alarm should be raised - this will deter attempts to tamper with the biometric authentication or locks as well as prevent an unconscious human to remain trapped in the door for a prolonged amount of time
- Human sickness/panic - a large and visible panic button must be present inside the deadman door, to be activated upon human sickness/panic. Upon pressing this button, an alarm should be raised, an audible alarm with independent power source should be triggered and the electronic locks of the outside door must be unlocked.
- Fire - the inside of the deadman door should have a fire sensor, and may have even a sprinkler system. Upon detecting a fire, the sprinkler system should be activated (if placed), an alarm should be raised and all locks of the both doors must be bypassed and unlocked.
- Power outage - all door systems and authentication databases must have a UPS which will provide power surge and brownout protection, and will provide independent operation in short periods of power outage.
Talkback and comments are most welcome