Physical unclonable function
Essentially, in each PUF circuit, electric current may move through this circuit in two distinct ways/paths, such as two wires. If it goes mostly through one of these ways/paths, a logical zero is produced, whereas if it goes through the other way/path, a logical one is produced. The prevalent path is chosen according to tiny details (characteristics) of the circuit, such as which wire is thicker or longer. However, the two wires have been designed to be exactly the same, and only differ because of imperfections of the manufacturing process, which cause random tiny mistakes (imperfections), such as one wire being 5 mm, and the other 5.00001 mm. Therefore, and as the choice of the prevalent path is dependent on a large number of tiny details (thickness, length, resistance of the wires, etc.), which are very difficult to determine beforehand, this choice appears as random, and can be considered as chaotic. The tiny production mistakes that affect the path choice cannot be predicted as they happen randomly in the manufacturing process. Nevertheless, after they happen, they stay like that, for example, the small difference in length between two wires will always exist after they have been manufactured, so the aforementioned path choice is "locked", although it is "random" (chaotic), and will always give the same result.