A lock picking technique for opening a pin tumbler lock using a specially crafted bump key

Did you know that the average mechanical key lock on most homes can be easily breached by a simple method called ‘key bumping’.

What is it and how can it affect me?

The cylinder lock is the most common type of lock in use today. Most cylinder locks use a pin and tumbler system which is comprised of upper and lower pins of varying length, along with small springs. Lock or key bumping works in the same manner as lock picking, where the pins within the cylinder must be moved into the proper position to allow the lock to open.

A standard key uses a series of ridges to align the pins into their proper position. When properly aligned (with the correct key) the cylinder can then turn freely. Lock manufacturers assign key codes to both key blanks and locks. These key codes refer to what depth the key blank should be machined, and to what size pins should be used within the lock set.

Bump keys are made by machining a key blank to the lowest factory setting (key code). Once you have selected the correct bump key for the lock, the key is then “bumped” into the cylinder allowing the pins in the cylinder to separate. This then allows the lock cylinder to turn and entry is gained.

A lock which has been ‘bumped’ shows no sign of forced entry, as there is none. It is very hard to prove to insurance companies that you have been robbed if entry was gained by key bumping.

Watch the video below from ‘A Current Affair’ for more information.