Rollingcode

A rolling code or hopping code is often used in radio-based vehicle opening systems or input control systems such as garage door openers, to authenticate a legitimate user wirelessly. At this time, based on a shared secret between the sender and recipient ( " symmetric key " ) and a suitable cryptographic algorithm, a received are always changing so-called next- code to the receiver from the transmitter to check (verify). The next code is never actually repeated directly from the transmitter to make it harder replay attacks, but is nevertheless always an element of a predefined, suitably long, cyclic durchiterierten list (hence the term rolling code ). A well-known, widespread Rolling - code is an example of the Keeloq algorithm.

• Authentication technique