How safe is the lock?

Those who watch carefully must know that there are often several small round holes in the lock cylinder of the padlock, except for the keyholes. What are the holes used in these locks? Corresponding to a circular hole, in the space inside the lock body, you can place a spring and two copper balls of different height, then how do we unlock the key, the tooth position of each key is different, this is It is specially designed for the lock body, which is why a key opens a lock, the tooth position on the key is inserted into the lock cylinder, and the two marbles are topped at different heights. At this time, the two marbles in the hole are The boundary, the height of the circumference of the lock cylinder, is what we usually hear when we hear it, so we can turn the key and open the lock.

So how does the thief unlock it? In fact, it is constantly imitating the tooth position of the key to achieve the purpose of pushing the internal marble.