AN INTERACTIVE IDENTIFICATION SCHEME BASED ON DISCRETE LOGARITHMS AND FACTORING

We describe a modification of an interactive identification scheme of Schnorr intended for use by smart cards. Schnorr's original scheme had its security based on the difficulty of computing discrete logarithms. The modification that we present here will remain secure if either of two computational problems is infeasible, namely factoring a large integer and computing a discrete logarithm. For this enhanced security we require somewhat more communication and computational power, but the requirements remain quite modest, so that the scheme is well suited for use in smart cards.