Advice on Security Issues

Locks & Keying Systems

Locks come in many forms and are available with a wide variety of operating mechanisms ranging from simple mechanical pin or lever operation to sophisticated electro-magnetic systems. For the purpose of this document we have restricted our coverage to mechanical locks and keying options.

Mechanical locks come in many shapes and sizes and basically consist of two main elements, the mechanism and its casing (which keeps the mechanism together).

In this basic state, locks are seldom attractive or secure and are intended for incorporation into an end user product. The padlock for instance is a lock mechanism/housing (cylinder) which has been incorporated into a higher security body or housing (sleeve) for stand alone use. The same lock (cylinder) however could easily be incorporated into a vending machine or conventional door lock, etc
The internal mechanism of a lock will vary according to the lock type but in simple terms, a number of pins or levers must be correctly aligned before the key will turn and the lock can be operated. ( please note; for simplicity we will use the term Pins throughout the rest of this article to represent pins or levers )

Lock Performance / Security Levels

A number of things will have a direct bearing on the performance and effectiveness of a lock:

The number of Pins in the mechanism will limit the number of possible key differs (different key patterns) the lock could have.

Whatever the theoretical number of possible differs for a given lock, for practical reasons only a limited selection will normally be manufactured.

For any given lock the number of key differs could range from as low as twenty (or even a single differ for very simple locks like cupboard locks), to several million and care should be taken to ensure that the selected lock will offer an adequate number of differs for the use it is to be put.

Materials used in manufacture will also have a bearing on the locks performance. To keep manufacturing costs down the lock body (casing) could be cast from a soft metal alloy, although in a similar style higher cost lock it may be machined from solid brass. Internal mechanisms of higher specification locks will also be manufactured from special materials designed to suit the environment in which the lock may be used. Locks used in a hostile / external environment will benefit from the use of anti corrosive materials & finishes in component manufacture, whilst the use of special hardened steels for pins, etc. may extend the operational life of the lock.

The way that the lock is incorporated into the end product will also have a dramatic impact on its relative performance. A low specification lock installed in a high security housing within a product, could offer a better overall level of protection than a poorly integrated high specification lock in the same product.

The main principle of operation varies according to lock type, however in simple terms once the pins are aligned, turning the key will either swing a Cam through 90 or 180 degrees (typically as used for locking cash boxes, etc). Alternatively turning the key could drive a tongue out through a slot in the lock housing (typical of the operation of a conventional Mortice or Safe Lock).

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