Method for secure exchange of messages between electric charging terminal and e.g. electric car, involves transmitting response message containing authentication code to car, where code is used when code is representative of session key

摘要

The method involves generating a random number associated with a secret key in a car (E1), and transmitting a message containing the random number, an identifier of the car, and a query to an electric charging terminal (E2). A session key is generated with parameters for the secret key, and a passcode is generated with parameters for the session key. A response message containing an authentication code is transmitted to the car, and another session key is generated using the secret key and the random number, where the code is used when the code is representative of the latter session key.