Patent ID: 8384546

Claim:
A method of providing security in an RFID system comprising the following steps: a. transmitting a challenge to an RFID tag; b. generating a first response at the RFID tag by performing at least one mathematical function using the challenge and a secret; c. transmitting data to a verification device; d. using a secret stored in the verification device and the transmitted data to generate a second response at the verification device; e. comparing the first response to the second response; and then f. determining the authenticity of the RFID tag based on said comparing step; g. transmitting said challenge to the verification device; h. providing the RFID tag with an integrated circuit which comprises a plurality of conductive traces; i. providing a set of instructions incorporated into a memory of the integrated circuit installed on the RFID tag, said set of instructions including instructions to send an electric signal across each of a pair of said conductive traces; j. measuring the amount of time for electricity to flow across the first conductive trace; k. measuring the amount of time for electricity to flow across the second conductive trace; l. comparing the times measured in steps j. and k.; and then m. generating a digit of the secret based on said time comparison step.