back to: Kickthefog.com
Most people carry five to 10 keys with them whenever they go out. On your key ring you might have several keys for the house, one or two more for the car and a few for the office or a friend's house. Your key ring is a clear demonstration of just how ubiquitous lock technology is: You probably interact with locks dozens of times every week.
The main reason we use locks everywhere is that they provide us with a sense of security. But in movies and on television, spies, detectives and burglars can open a lock very easily, sometimes using only a couple of paper clips. This is a sobering thought, to say the least: Is it really possible for someone to open a lock so easily?
Under Lock and Key
Locks come in all shapes and sizes, with many innovative design variations. You can get a clear idea of the process of lock picking by examining one simple, representative lock. Most locks are based on fairly similar concepts.
Think about the normal dead-bolt lock you might find on a front door. In this sort of lock, a movable bolt or latch is embedded in the door so it can be extended out the side. This bolt is lined up with a notch in the frame. When you turn the lock, the bolt extends into the notch in the frame, so the door can't move. When you retract the bolt, the door moves freely.
The lock's only job is to make it simple for someone with a key to move the bolt but difficult for someone without a key to move it. In the next section, we'll see how this works in a basic cylinder lock.
The Pin is Mightier than
Inside a cylinder lock, there is a sort of puzzle, which only the correct key can solve. The main variation in lock designs is the nature of this puzzle. One of the most common puzzles -- and one of the easiest to pick -- is the pin-and-tumbler design.
The main components in the pin-and-tumbler design are a series of small pins of varying length. The pins are divided up into pairs. Each pair rests in a shaft running through the central cylinder plug and into the housing around the plug. Springs at the top of the shafts keep the pin pairs in position in the plug. When no key is inserted, the bottom pin in each pair is completely inside the plug, while the upper pin is halfway in the plug and halfway in the housing. The position of these upper pins keeps the plug from turning -- the pins bind the plug to the housing.
When you insert a key, the series of notches in the key push the pin pairs up to different levels. The incorrect key will push the pins so that most of the top pins are still partly in the plug and partly in the housing. The correct key will push each pin pair up just enough so that the point where the two pins come together lines up perfectly with the space where the cylinder and the housing come together (this point is called the shear line). To put it another way, the key will push the pins up so that all of the upper pins are inserted completely in the housing, while all of the lower pins rest completely in the plug. Without any pins binding it to the housing, the plug moves freely, and you can push the bolt in and out.
This simple puzzle design is very effective. Since the pins are hidden inside the lock, it's fairly difficult for most people to move the plug without the correct key. But, with a lot of practice, it is possible to solve the puzzle by other means. In the next section, we'll see how a locksmith goes about picking this sort of lock.
The Weakest Link
There are two main elements involved in the picking process:
The first step in picking a lock is to insert the tension wrench into the keyhole and turn it in the same direction that you would turn the key. This turns the plug so that it is slightly offset from the housing around it. As you can see in the diagram below, this creates a slight ledge in the pin shafts.
While applying pressure on the plug, you insert a pick into the keyhole and begin lifting the pins. The object is to lift each pin pair up to the level at which the top pin moves completely into the housing, as if pushed by the correct key. When you do this while applying pressure with the tension wrench, you feel or hear a slight click when the pin falls into position. This is the sound of the upper pin falling into place on the ledge in the shaft. The ledge keeps the upper pin wedged in the housing, so it won't fall back down into the plug. In this way, you move each pin pair into the correct position until all of the upper pins are pushed completely into the housing and all of the lower pins rest inside the plug. At this point, the plug rotates freely and you can open the lock.
Another technique is raking. Raking is much less precise than actually picking. To rake a lock, you insert a pick with a wider tip all the way to the back of the plug. Then you pull the rake out quickly so that it bounces all of the pins up on its way out. As the rake exits, you turn the plug with the tension wrench. As they're moving up and down, some of the upper pins will happen to fall on the ledge created by the turning plug. Often, locksmiths will start by raking the pins, and then pick any remaining pins individually.
Conceptually, the lock-picking process is quite simple, but it is a very difficult skill to master. Locksmiths have to learn exactly the right pressure to apply and what sounds to listen for. They also must hone their sense of touch to the point where they can feel the slight forces of the moving pins and plug. Additionally, they must learn to visualize all the pieces inside the lock. Successful lock picking depends on complete familiarity with the lock's design.
Another common type of cylinder lock is the wafer-tumbler lock. These work the same basic way as pin-and-tumblers, but they have thin wafer-shaped tumblers rather than pins. You pick the wafers exactly the same way you pick pins -- in fact, it is a little bit easier to pick wafer-tumbler locks because the keyhole is wider.
Some designs use single wafers rather than wafer pairs. These wafers are spring loaded so that they extend out of the cylinder, binding with the lock housing. The wafers have a hole in the center that the key will fit through. The correct key pulls the wafers down just enough so that they are all retracted into the plug. The incorrect key will either pull the wafers down only part of the way or will pull them down too far, causing them to extend out the other side of the plug.
Double-wafer locks have wafer tumblers on both ends of the plug. To pick these locks, you work the wafers on both sides as you apply pressure with the tension wrench. Wafer locks are found in most filing cabinets, lockers and cars, as well as in many padlock designs.
Tubular locks offer superior protection to pin-tumbler locks and wafer-tumbler locks, but they are also more expensive. Instead of one row of pins, tubular locks have pins positioned all the way around the circumference of the cylinder plug. This makes them much harder to pick. Conventional lock-picking techniques usually don't work on this type of lock.
Some pin-tumbler locks have modified pins that make picking more difficult. In the most common variation, the upper pins have a mushroom-shaped head. This odd shape causes the plug to shift early, before you have actually pushed the top pin all the way up. This makes it more difficult to put the pins in position. It also makes it very hard to get an accurate feel for what's going on inside the lock.
Re-Keying a Lock
To make a new key for an existing lock, you cut a series of notches in the key so that it raises each of the upper pins just above the shear line. Essentially, you cut a pattern in the metal that matches the pattern of the pins in the lock. To change a lock so that it fits an existing key, you simply work in the opposite direction: You change the pattern of the pins in the lock so that it matches the pattern of notches in the key. If the lock is designed with a universal keying system, any locksmith can re-key the lock in no time. You can also get locks re-keyed at most hardware stores.
In this basic six-pin lock set, you can see how this re-keying works. When you open up the shafts in the cylinder and empty them out, you have six springs and 12 tiny pins. All of the upper pins are exactly the same size. The remaining six pins (the lower pins) will be of various lengths to match up with the notches on the key.
The process of re-keying a lock is very simple. The locksmith removes all of the pins from the cylinder. Then, drawing from a collection of replacement pins of various sizes, the locksmith selects new lower pins that fit perfectly between the notches of the key and the shear line. This way, when you insert the new key, the lower pins will push all the upper pins just above the shear line, allowing the cylinder to turn freely. (This process may vary depending on the particular design of the lock).
It doesn't matter how long the upper pins are (since they all rest above the shear line when the key is inserted), so the locksmith simply re-inserts the six original upper pins that came with the lock. And that's all there is to re-keying. The entire process takes only a few minutes.
The Picker Code
Lock-picking skills are not particularly common among burglars, mainly because there are so many other, simpler ways of breaking into a house (throwing a brick through a back window, for example). For the most part, only intruders who need to cover their tracks, such as spies and detectives, will bother to pick a lock.
Somewhere between the locksmith and the burglar is the recreational lock-picker, sometimes called a hacker. Like expert computer hackers, their code is to pick locks for the fun of it. Of course, breaking into any private property, no matter the intent, is illegal and unethical. If a person picks a lock that belongs to someone else, chances are the person will be arrested and face serious breaking-and-entering charges.
Simply understanding the principles of lock picking may change your whole attitude toward locks and keys. Lock picking clearly demonstrates that normal locks are not infallible devices. They provide a level of security that can be breached with minimal effort. Most locks serve only to keep honest people honest and to discourage criminals. With the right tools, a determined intruder can break into almost anything.
back to: Kickthefog.com