An integrated device for physically unclonable functions is based on a set of MOS transistors exhibiting a random distribution of threshold voltages which are obtained by lateral implantations of dopants exhibiting non-predictable characteristics, resulting from implantations through a polysilicon layer. A certain number of these transistors form a group of gauge transistors which makes it possible to define a mean gate source voltage making it possible to bias the gates of certain others of these transistors (which are used to define the various bits of the unique code generated by the function). All these transistors consequently exhibit a random distribution of drain-source currents and a comparison of each drain-source current of a transistor associated with a bit of the digital code with a reference current corresponding to the average of this distribution makes it possible to define the logical value 0 or 1 of this bit.