Locksmiths have long opened doors by inserting a blank key from a lock manufacturer into a matching lock and striking it to "bump" all the pin tumblers, opening the lock. Locksmiths only did this at the request of legitimate customers. As videos demonstrating the bumping technique have spread around the internet, homeowners and business owners have increasingly started to fear break-ins from burglars with bump keys. New high security locks are available that cannot be bumped, however.
Digital locks cannot be bumped because they operate without a mechanical key. Some electronic locks require the user to type in a code on a keypad, while others require a card to be swiped. Some even read fingerprints to allow access.
Some manufacturers of high security deadbolt locks manage the keys, or key blanks, for their locks with a controlled system that eliminates unauthorised duplication of keys. Only the manufacturer and authorised dealers have access to the key blanks.
Deadbolt locks that use a side-locking bar instead of the traditional pin-and-tumbler system cannot be bumped. Some lock makers manufacture deadbolts with a side-locking bar in addition to pin-and-tumblers; if the manufacturer makes sidebar cuts in the keys before sending them to the dealer, however, someone may be able to use the key to bypass the side-locking bar and bump the lock. So look for side-locking bar locks that don't also use the pin-and-tumbler system.
Multiple Locking Technologies
Locks utilising multiple locking technologies are resistant to bumping. These high security locks use a sidebar mechanism combined with secondary locking mechanisms. In some models, the secondary mechanism consists of a special elevating and rotating pin tumbler design coupled with false slots on the bottom pins and mushroom top pins. In other designs, dual sidebar locks are combined with a large number of bottom pins and a patented U-shaped key with a trigger mechanism, making the lock bump proof.
Sliders and Disks
Some high security deadbolts use disks that operate much the same way that those on a safe dial do. Other deadbolts use a system of sliders with one slider for each key cut. In addition, these sliders do not create a vertical shear inside the lock, as the traditional pin-and-tumbler system does, making the slider system lock impossible to bump.
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