Patent ID: 7058814

Claim:
An identification system for use with an identification medium to provide time-limit access to a resource, comprising: a transmitter module secured to the identification medium; a receiver module in selective communication with the transmitter module; the transmitter module including an encryptor and a time generator that generates a temporal sequence of values (T Bn ), wherein the encryptor encrypts the temporal sequence of values (T Bn ) with a private, non-public key K n which is unique to the identification medium, to generate a code list composed of encrypted code elements (T Bn )K n ; wherein the transmitter module transmits one or more encrypted code elements (T Bn )K n to the receiver module; an authenticator in communication with the receiver module that has access to a subset of the encrypted code elements of the code list; and wherein the subset corresponds to a specific time window during which access to the resource is authorized, so that the authenticator is capable of authenticating the identification medium without resorting to the private key, and only during the specific time window corresponding to the subset of the encrypted code elements, by mapping the subset of the encrypted code elements (TBn)Kn, in order to enable time-limited access to the resource during the specific time window.