SMARTRA
From OpenGK
SMARTRA (SMARt TRansponder Antenna) is a passive challenge-response immobiliser system developed for HMC (Hyundai Motor Company) by Bosch. On the GK platform, version 2 is used, called SMARTRA2.
Not much information can be found online about version 2 of SMARTRA. However, version 3 is backwards compatible and thanks to the FCC, it's protocol specification document is available.