Lock Bumping



Lock bumping is a lock picking technique for opening a pin tumbler lock using a specially-crafted bump key. One bump key will work for all locks of the same type.

In the 1970s, locksmiths in Denmark shared a technique for knocking on a lock cylinder while applying slight pressure to the back of the lock plug. When the pins would jump inside of the cylinder, the plug would be able to slide out freely and disassemble the lock quickly. The use of a bump key was not introduced until some time later and was first recognized as a potential security issue around 2002-2003 by Klaus Noch who brought it to the attention of the German media. After further examination of the procedure, a white paper was drafted in 2005 by Barry Wels & Rop Gonggrijp of The Open Organization Of Lockpickers (Toool) detailing the method and its applicability.

The technique then attracted more popular attention in 2005 when a Dutch television show, Nova, broadcast a story about the method. After the method received further publicity from Toool presentations at security conference talks, members of Toool and a Dutch consumer group, Dutch Consumentenbond, analyzed the capability of the method on 70 different lock models and with trained and untrained users in a 2006 study.

At the same time, Marc Weber Tobias, an American security expert, began to talk publicly in the United States about the technique and its potential security threats. In 2006, he released two further white papers regarding the technique and its potential legal ramifications.

A bump key is made by filing down a key blank (or another key made for the targeted type of lock) to the lowest level in each groove. Slight elevations are left between the grooves--if these are too steep, the key will not enter or leave the lock. The tip and shoulder of the key must also be filed down.

Ironically, more precise manufacturing tolerances within the cylinder make bumping easier as the pins move more freely and smoothly. Also, more expensive locks made of hardened steel are actually more vulnerable because they are less prone to damage during the bumping process which might cause a cheaper lock to jam.

Locks having security pins (spool or mushroom pins, etc.)—even when combined with a regular tumbler mechanism—generally make bumping somewhat more difficult, but not impossible.

Electronic locks, magnetic locks, and locks using rotating disks are not vulnerable to this attack.

Because a bump key must have the same blank profile as the lock it is made to open, restricted or registered key profiles are much safer from bumping, as the correct keyblanks cannot legally be obtained without permission and/or registration with relevant locksmiths' associations.

Locks made by Medeco or Mul-T-Lock (sister companies) are generally thought to be "bump proof."Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts.
Virtual Magic is a human knowledge database blog. Text Based On Information From Wikipedia, Under The GNU Free Documentation License. Copyright (c) 2007 Virtual Magic. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

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