PROCEDE DE DETERMINATION D'UNE CLE DE CRYPTAGE ASSOCIEE A UN CIRCUIT INTEGRE

摘要

A method for determining an encryption key associated with an integrated circuit (10) having a memory plane (11) is disclosed. The method comprises the steps of (a) forming a matrix of N electrical contacts Ci (i = 1, ..., N) on the surface of said memory plane (11), (b) depositing a layer (14) of a material having random inhomogeneous electrical resistivity on said matrix, and (c) determining said encryption key or resistive key Kr on the basis of the random distribution of electrical resistances connecting the various electrical contacts Ci of the matrix. The method is useful for protecting smart cards used in coded television services.