Method for performing cryptographic authentication in a radio frequency identification system

摘要

The method of cryptological authentification in a scanning identification system comprising a base station, which supplies energy via the alternating field to a transponder connected to the object to be identified, includes the following method steps. For essentially the entire communication between the base station and the transponder, the base station generates an inquiry signal. Upon receiving the inquiry signal transmitted by the base station, the transponder responds with an identification number stored in its memory. The base station then encodes a first bit sequence it has generated by using a key bit sequence that is allocated to the identification number of the transponder, and transmits the second bit sequence obtained in this manner to the transponder. When the second bit sequence is received, the transponder generates a checking bit sequence from the second bit sequence, and, following the complete reception of the second bit sequence, transmits this checking bit sequence to the base station. The checking bit sequence serves to verify the correct reception of the second bit sequence. For cryptographic authentification, the transponder encodes the first bit sequence reconstructed from the second bit sequence using the key bit sequence allocated to the transponder, and transmits the third bit sequence obtained in this manner to the base station. While the transponder is still encoding the second bit sequence to form the third bit sequence, the base station uses the checking bit sequence to verify whether an error has occurred in the transmission of the second bit sequence, and may abort the ongoing encoding in the transponder. This can abort the ongoing authentification, because a valid result cannot be anticipated. Thus, time is gained at the start of a new running of the authentification method.