Patent ID: 7450010

Claim:
A communications system comprising: a radio frequency identification (RFID) tag comprising a tag memory storing a private key and a tag identification (ID), a tag random number generator for generating a first random number, a tag authentication code generator, and a tag processor for causing the tag ID to be transmitted; and, a RFID reader comprising a reader random number generator for generating a second random number, a reader memory storing private keys for tags and tag IDs, each private key associated with one of the tag IDs, a reader processor for receiving the tag ID transmitted from the RFID tag and retrieving from said reader memory the tag private key associated with the received tag ID, a reader authentication code generator for receiving the first random number, the second random number, and the retrieved tag private key, said reader authentication code generator generating a reader authentication code based on the private key, the first random number, and the second random number, wherein said reader processor causes said reader authentication code to be transmitted to said tag; wherein said tag authentication code generator further generates a reader authentication code based on the private key, the first random number, and the second random number, and said tag processor determines whether the reader is authentic based on a comparison of the reader authentication code transmitted by the reader and the reader authentication code generated by the tag authentication code generator.