I've been reading around the forum for a while, and I thought I would try to give a little something back.
The aim of this post is to provide a very basic overview of security in pin tumbler locks. I will assume that you have read up on how locks work. The material covered in this post will be mainly over basic types of security pins, with a brief mention of restrictive keyways.The basic security measures involved when attempting to further secure a pin tumbler lock depend upon the fundamental principle of the cylinder lock.
This principle is that of rotation and the blocking thereof. This begs the following question;
What is it about locks and locking mechanisms that says that it has to rotate to open?
One answer is that all other non-rotational forces within a pressure-activated components are too easy to simulate. You can push, pull, and wiggle anything with a hole in it. Particularly if it's a matter of pressure-activated components like pins and wafers.
As lockpickers, we are uniquely aware of the vulnerabilities of pressure-activated components in rotation-based locking systems. This rotation and blocking system implies a shear line, with which we are all familiar. This same rotation and shear line equals binding, and binding equals individual component manipulation. Even the "juggernauts" of the lock industry like Medeco are subject to this basic vector of attack.
If anyone has any further input on why locks should rotate, please do let us know. I admit that I have done little research into this.So the question then becomes "How do we prevent manipulation?"This has been answered in several ways. The most common are restrictive keyways and security pins. Schuyler Towne has a
video on YouTube on making your own security pins with a power drill and a file set. These security pins counteract manipulation in several ways.
Spool Pins - The most basic anti-picking pin. It is shaped like a thread spool, providing a "false set" when raised to the shear line. The presence of a spool pin's false set is accompanied with a very slight rotation of the plug, often somewhere around 15 degrees of rotation. To the inexperienced or inattentive picker, this pin is the cause of much frustration. A simple backing off of the tension and a little extra pressure on the pin will raise this pin to the shear line.
Serrated Pins - A slightly more complex anti-picking pin, the serrated pin is mainly used to frustrate overlifting attacks. When overlifted, a serrated pin will catch on the shear line several times on its way down. This is to trick the picker into thinking that his or her overlifting attack has succeeded and he or she has dropped the pin to a clear shear line. These pins are quite frustrating if one is not aware of the pin's presence and if an overlifting attack has been attempted.
Mushroom Pins - A mushroom pin is shaped like, you guessed it, a mushroom. When lifted, the mushroom pin will force a picker to rotate the plug back toward the locked position, much as a spool pin will behave, although not in such an exaggerated manner. If one is not careful, the dropping of previously-set pins is likely. The techniques for the defeating of a mushroom pin are identical to those of defeating a spool pin.
There are various hybrids of these pins, including spoorated and barrel pins, but they are not often found in basic cylinder locks, and as such are beyond the scope of this post.
Not all security pins are located in the bible of the lock. The key pins can also be security pins. This is particularly frustrating if the pin is overlifted by the picker and the security feature is engaged by the shear line. Often, this results in having to start over.
Another way to nullify this binding and manipulation attack is to abandon the concept of the rotational cylinder lock.
I will be honest and admit that I am not familiar with any such system, and I welcome any input on that front. Earlier, I mentioned restrictive keyways. The purpose such keyways serve is basically the frustration of picking attacks. The keyway will often block access to the key pins. However, no matter how restrictive the keyway is, the key must be able to interact with the key pins, and it is therefore possible for the key pins to be accessed by a pick tool. For extreme examples of such keyways, see the majority of the ASSA ABLOY group, particularly EVVA and ABUS locks.
Other restrictive keyways do not focus on the warding of the keyway itself, but rather on shrouding the keyway when the proper key is not in use.
If there is any further information which any forum members find that I have missed in this very basic overview, I welcome your input.There is no means by which I can be removed from the love of God. For this, I am indescribably glad.
