The security industry typically uses rolling code algorithms to authenticate sender & receivers in keyless entry systems, which is called RKE (ex: KeeLoq).
In key-less smart key car system,
The transmitter periodically (at interval of 1-2 seconds) sends a low power RF signal. If a receiver is around it will check the rolling code sequence and match the code to authenticate (confirm this is how it works ?)
However, since the sender is periodically outputting a signal, can't the key easily go out of the sequence for rolling code sequence, how does it manage this part ?
Or does it use two-way communication to synchronize and increment the sequence counter?
Also, what does the exact signal look like that key sends to receiver, is it sequence number and some X bit code?
If I apply a range extender to the sender & receiver so that I can crack the key and get into the car without being key near to car,
Does the algorithm takes care of this scenario ? And if yes, how?