1. A method comprising: receiving identification information from a device; sending a first challenge to a device, the first challenge selected from a database associated with the received identification information, the database including data characterizing a plurality of first challenges and a plurality of corresponding responses, each response associated with a corresponding first challenge; receiving a volatile response from the device, the volatile response determined in the device according to a sequence of challenge values generated in the device on the basis of the first challenge; and authenticating the device using the received volatile response and the response corresponding to the sent first challenge.