Abstract
This paper describes the different data processing methods and crypto algorithm principles of access/drive authorisation systems used in modern vehicles. The various communication sequences between keyhead/keyfob and vehicle are detailed. Some possible attacks by thieves on a remote entry control system and the countermeasures required are discussed. Illustrations are given for a system overview, RF-receiver modules, bandwidth comparison, range performance, assembly of a plastic transponder, immobiliser module, "rolling-code" and "challenge & response" principle. (A)