METHOD, RFID READER, RFID TAG AND RFID SYSTEM FOR SECURE COMMUNICATION

摘要

In an RFID system a method for communication between a reader (1) and a tag (2) comprises: at the reader (1), switching on an electromagnetic signal (SS) for energizing the RFID tag (2) and/or transmitting an instruction (INST, RNREQ) or first data (Dl) to the tag (2); at the tag (2), generating a random number (RN), converting said random number (RN) into a random time period (tx) and transmitting a response to the reader (1) after a delay time that corresponds to the random time period (tx); at the reader (1), measuring the random time period between transmitting the instruction (INST, RNREQ) or first data (Dl) to the tag (2), receiving the response (RESP) from the tag (2), reconverting the measured random time period (tx) into the random number (RN), encrypting second data (D2) with the random number (RN) and transmitting said encrypted data (ED) to the tag (2); at the tag (2), decrypting the encrypted data (ED) by the use of the random number (RN).