METHODS AND SYSTEM FOR SECURE COMMUNICATION BETWEEN AN RFID TAG AND A READER

Methods and a system involve secure communication between an RFID tag and a reader via the over-the-air interface, and to corresponding RFID tags and corresponding readers. A modification of the Rabin method is employed wherein within the framework of the encryption of a plaintext M into which an identification element of the RFID tag or of an object furnished therewith is incorporated, there is computed by the RFID tag, the Montgomery residue (Montgomery reduction) of the square of the plaintext M modulo n with respect to a Montgomery base R, i.e. C*=M2R−1 mod n, and the resultant ciphertext C* is employed for authenticating the RFID tag. The modulus n=p·q is the public key of the reader, the prime numbers p, q are the private key of the reader, and the Montgomery base R is an integer that is larger than the modulus n.