Abstract: A system for electronic access control including a mobile processing device owned by a user, a barrier, a control unit, and a remote coordination processing device. The mobile processing device includes a component for storing personal access credentials related to the user and a short-range wireless communication module. The mobile processing device, the control unit and the remote coordination device are connected through a telematic communication network. The system further includes at least one short-range wireless local receiver, which is connected to the control unit and is arranged proximate to the barrier. The short-range wireless local receiver and the control unit are configured to define at least one vector for the location of a signal emitted by the short-range wireless communication module of the mobile processing device. The signal includes the personal access credentials of the user.

Abstract: A prepaid card with elements for preventing useful fraudulent alteration, comprising, on a supporting element, at least one electrically rewritable permanent register, at least one temporary register and at least one control element for comparison between a usable value that is present in the at least one permanent register and a new value which is temporarily provided in the at least one temporary register. The control element is suitable to allow to write the new value in the permanent register in replacement of the usable value only if the new value is smaller than the usable value.

Abstract: Method for obtaining authenticity identification devices for using services in general wherein authenticity is guaranteed without resorting to the manufacturer of the device to ensure its validity; the method has the particularity that it consists in preparing an identification device with a read-only area and at least one writable area; the manufacturer of the device applies a first permanent and always different code to the read-only area. The service provider applies to the writable area a second code obtained by means of one-way functions that have a secret encryption key by computing the first permanent code. The identification device validated with the second code can be verified by means of a decryption key which may optionally be public.