The invention relates to semiconductor devices, and more particularly, to systems, devices and methods of utilizing inherent differences among physical elements in an electrical component to generate unique and non-duplicable numbers that are statistically random and repeatable. These bits may be applied as identifications, random number seeds or encryption keys in many security applications, e.g., a financial terminal. An integrator is coupled to a plurality of physical elements, selects two physical elements or element sets, and generates an integrated difference signal according to a difference between these two physical elements or element sets. A comparison-decision logic further determines whether the difference between the selected two physical elements is associated with a bit of “1” or “0”. In some embodiments, a multi-bit number constitutes multiple bits each of which may be derived from a difference between two randomly selected physical elements or element sets.