Rolling code

[citation needed] Remote controls send a digital code word to the receiver.

A rolling code system uses cryptographic methods that allow the remote control and the receiver to share codewords but make it difficult for an attacker to break the cryptography.

The Microchip HCS301 was once the most widely used system on garage and gate remote control and receivers.

In 2015, it was reported that Samy Kamkar had built an inexpensive electronic device about the size of a wallet that could be concealed on or near a locked vehicle to capture a single keyless entry code to be used at a later time to unlock the vehicle.

Kamkar stated that this vulnerability had been widely known for years to be present in many vehicle types, but was previously undemonstrated.