Method for communication and verification of authentication data between a portable device with transponder and a vehicle reading unit

摘要

The method involves calculating a new cryptic function by a random number generated in a reader unit (2) and a secret key in an electrically EPROM memory (13). A cryptic function formed based on the number and a secrete key in an encrypting and/or decrypting circuit is transmitted to the reader unit when the new function is equal to another received cryptic function. The former function is validated to authorize the access to a vehicle.