METHOD OF PROTECTION IN A CONTACTLESS RADIOFREQUENCY COMMUNICATION

摘要

The invention relates to a method of protection of a near-field contactless communication system (RFID or the like) against malicious attacks. The method comprises the exchanging between a reader and a contactless card of information regarding a chosen value of duration T, measured with respect to a start instant t0 seen from the reader side, the decoding of this information regarding a value of duration T by the card, the sending by the card of a return signal temporally registered with respect to an instant t'0+T, where t'0 is the start instant such as seen by the card having regard to lags in propagation or processing of the signals received from the reader, the detection of the return signal by the reader, the determination of the temporal registration of the return signal with respect to the start instant t0, and the interruption of the dialogue by the reader if the temporal registration of the return signal detected is not equal to the instant t0+T with a predetermined error margin. The return signal is a pseudo-random sequence.