model that highlights interactions between pin positions.
Chapter 4 uses this model to explain how picking works.
Chapter 9 will use this model to explain complicated
mechanical defects.
In order to become good at picking locks, you will need a
detailed understanding of how locks works and what happens as
it is picked. This document uses two models to help you
understand the behavior of locks. This chapter presents a
model that highlights interactions between pin positions.
Chapter 4 uses this model to explain how picking works.
Chapter 9 will use this model to explain complicated
mechanical defects.
The "flatland" model of a lock is shown in Figure 3.1 This
is not a cross section of a real lock. It is a cross secrtion
of a very simple kind of lock. The purpose of this lock is to
keep two plates of metal from sliding over each other unless
the proper key is present. The lock is constructed by playing
the two plates over each other and drilling holes which pass
through both plates. The figure shows a two hole lock. Two
pins are placed in each hole such that the hap between the
pins does not line up with the gap between the plates. The
bottom pin is called the key pin because it touches the key.
The top pin is called the driver pin. Often the driver and
the key pins are just called the driver and the pin. A protrusion
on the underside of the bottom plate keeps the pins from
falling out, and a pring above the top plates pushed down on
the driver pin.
If the key is absent, the plates cannot slide over each other
because the driver pins pass through both plates. See Figure 3.3.
That is, the key lifts the key pin until its top reaches the lock's
sheer line. In this configuration the plates can slide past
each other.
Figure 3.3 also illustrates one of the important features of real locks. There is always a sliding allowance. That is, any parts which will slide past each other must be separated by a gap. The gap between the top and bottom plates allows a range of keys to open the lock. Notice that the right key pin in Figure 3.3 is not raised as high as the left pin, yet the lock will still open.
{page8 - diagrams p8a, p8b, p8c: labeled a] Figure 3.1: Flatland model of a lock b] Figure 3.2: (a) Flatland key raised pins c] Figure 3.3: (b) Proper key allows plates to slide. }