Perimeter Security, Part II

Locks

Locks can be used to secure access points throughout the location. Padlocks may used on the outer gate, mechanical locks on the building doors, and keypads on interior doors. These various types of locks provide different levels of security and have different features. It's important to understand that locks aren't truly a deterring factor in security, however. Many attackers see locks as a puzzle and a challenge; not a reason to give up.

Mechanical locks

There are two main types of mechanical locks: warded lock, and tumbler lock. The warded lock is a basic padlock. Inside of a warded lock, there is a spring-loaded bolt with a notch cut into it. The key fits into this notch and slides the bolt from the locked to the unlocked position. Additionally, there are wards, or metal projections, that the key is cut to fit around, as illustrated. Warded locks are the cheapest kind of lock because of their lack of sophistication and are also the easiest to pick.

Tumbler locks have more pieces and parts and can prove a more secure option. Within a tumbler lock, there are multiple metal pieces that have to be raised to a certain height before the bolt can be turned. The key for the lock will have the correct sequence of notches cut into it to allow it to raise each tumbler to the appropriate height. There are two common types of tumbler locks: pin tumbler and wafer tumbler. Pin tumbler locks (pictured left) use spring loaded pins inside of the lock. Pin tumbler locks are the most commonly used tumbler lock. Wafer tumbler locks are the small, round locks you usually find on file cabinets. They use a flat disk instead of a pin and are not as secure.

Combination locks require a combination to be entered which aligns internal wheels before being unlocked. These are the locks that you likely used in high school.

Programmable locks

Programmable locks, or cipher locks, are keyless locks that use a number pad to control access. The lock requires a specific combination to be entered and may incorporate other security devices such as a biometric scan or key card. Programmable locks cost more to install, but give the ability to change the code, lock out certain sequence patterns, and have codes for emergency situations such as if a person were under duress. In this situation, entering the emergency code will open the door while also triggering a remote alarm. Other features of programmable locks are:

• Door delay - If a door is held open for a given time, an alarm will trigger to alert personnel of suspicious activity
• Key override - A specific combination can be programmed for use in emergency situations to override normal procedures or for supervisory overrides
• Master keying - Enables supervisory personnel to change access codes and other features of the cipher lock
• Hostage alarm - If an individual is under duress and/or held hostage, a combination he enters can communicate this situation to the guard station and/or police station