How to Pick and Bump a Lock – Just In Case You Need To

Pin tumbler locks, from the cheapest to the most expensive all work in roughly the same way. The key slides down the keyway in the inner cylinder of the lock. As it moves, the cuts in the key move stacks of two or more pins, moving in holes drilled through the outer and inner cylinder. Small springs behind these pins push the pins back after a high point on the key has passed. When the correct key is all the way in and the ‘shoulder’ of the key rests against the inner cylinder, all the gaps between the pins inside the lock align on the ‘sheer line’, and the inner cylinder is free to turn.

Picking locks

Lock can be ‘picked’. A skilled operator can use tools to feel and move individual pins in the lock. Lockpicking allows one to open a lock by exploiting the fact that the pin stacks are never perfectly aligned. This causes some pins to be stuck between the inner and outer cylinder before others. It’s almost like a game of patience. Like a brain sharpening game. Because of this, one can feel that certain pins are correctly aligned before all the pins are aligned. And because the outer pins that would jam before others will remain on the outside of the inner cylinder after the lock is turned slightly, one can successively place the pins in the correct position and open the lock. Lockpicking takes quite a bit of practice. If you’re looking for fun, go play scary maze game or something.

Apart from intelligence professionals, criminals and locksmiths practicing it, lockpicking has become a regular sport, complete with official clubs and championships. It’s not like people are getting your online degree in lockpicking. Lock manufacturers have defended new locks against picking by inserting so-called ‘mushroom pins’, by making keyways narrower (providing less space for tools) and by lowering the mechanical tolerances of the lock manufacturing process. Going over the details of locks and lock picking would be outside of the scope of this paper.

Snapper pick, lockpick gun and vibrating tools

Another means of opening locks without the key is by using a snapper pick, lockpick gun or vibrating tool. These devices all exploit Newton’s law that says that for every action there is an equal and opposite reaction. Most people are familiar with Newton’s cradle, a device which is often used to demonstrate this law.
If a ball all the way on the left or right side is lifted up and let loose to collide with the row of suspended balls, this ball will transfer all its energy to the next ball and so forth, until the ball on the other end moves to swing away from the other balls. When it swings back, the process is reversed and the original ball swings up. The same principle can be observed during a game of billiards: one ball hits another one, and this ball continues onward whereas the first ball now lies still.

This principle can be used to open locks: if impulse energy is transferred to the first pin, it will tend to stay in place and the second pin tends to move away from the first one, until the spring stops it and pushes it back to touch the first pin.

A ‘lockpick gun’ such as the one shown below will, when the trigger is pulled, tension a spring and then when the trigger is pulled all the way use the force of that spring to snap the needle up for a short distance, but with a very sharp and powerful motion. By positioning this needle into the lock, just touching the pins, and then pulling the trigger, one tries to hit all the pins simultaneously. By then making the lock turn in the split-second before all the upper pins are pushed back by the springs in the lock, one can open the lock. The amount of turning force and the timing with which to apply it require some training.

Vibrating picks use the same principle except many times a second, requiring less training on the part of the operator. A snapper pick is the simpler version of a pick gun.
The lock industry has created locks that are more resistant to this technique. More resistant locks have narrower keyways, preventing tools from being inserted in the first place, and making it harder to transfer the impulse energy to the pins. More resistant locks also have smaller tolerances, creating less space for the pins to bounce around.

Bumping locks

Bumping, sometimes also called ‘Rapping’, has been a known technique for at least the past 50 years. A bump key is described in Marc Tobias’s reference work “Locks, Safes, and Security” [4] on page 603. Few people use the technique, and the method does not seem successful against a large number of locks unless the ‘minimal motion method’ described below is used. It takes great hand-eye coordination, patience, cognitive fitness and a technical mind to understand something you can’t see at the moment.

Once correctly used, we found this technique to be immensely powerful, allowing a large variety of locks to be opened. We did not invent this technique, and others probably thought of some of the same refinements we did. We do feel bumping is underestimated, and this paper exists to point to its effectiveness.

So we have a basic trick to open a lock by making the second pin jump away from the first, but no efficient means to apply this energy to the bottom pin. As it turns out, the best way to transfer energy to the pins is using a key. First of all, we need a ‘bump key’ for the lock in question. A bump key is a key in which all the cuts are at maximum depth. The picture below shows bump keys for various locks. Bump keys are sometimes called ’999′ keys because all cuts are at maximum (9) depth.

As you can see you can cut bump keys for both regular pin tumbler locks as well as for ‘dimple locks’, whether ‘pin-in-pin’ or not. Just remember to take away all the material that could be taken away by the deepest combination for that position.

There are machines that will cut a key based on the numbers that represent the depth at each position. Having access to such a machine speeds up the process of creating a bump key that has the cuts in the exact right position, although one can also use a file and a steady hand to create one. Bump keys, once cut, can be copied on regular key-cutting equipment. You do not necessarily need to have an uncut key (called ‘blank’) to make a bump key: because all the cuts of a bump key are at maximum depth, any used key for a given lock can be converted into a bump key.

Creating a Bump Key

The perfect lock does not exist. With enough training, tools and time, almost any lock can be manipulated. Practical security is almost always a trade-off between the cost of the lock and the time and effort needed for an attacker to open the lock. However: in terms of mechanical lock security, we believe that this vulnerability exposes a fundamental flaw in a large number of existing mechanical lock designs. Resistance against this attack will have to be incorporated in all future high-end locks, and judging by their own design criteria a large number of high-end locks seen today must be considered flawed.