There is described an optical fiber comprising a core with non-fungible noise elements along a length thereof, wherein the non-fungible noise elements generate in use a Physical Unclonable Function (PUF). There is further described an object including the present optical fiber and uses of the present optical fiber in applications such as authentication, encryption and zero trust security. There is also described an apparatus for introducing non-fungible noise elements along a core of a bundled optical fiber, a method for extracting a digital signature of a Physical Unclonable Function (PUF) generated by introduced non-fungible noise elements in the present optical fiber and a network integrating the present optical fiber.