Phone-as-a-Key (PaaK / Digital Car Key)
Definition of Phone-as-a-Key (PaaK) technology: how smartphones replace physical keys using Bluetooth Low Energy (BLE), NFC, and ultra-wideband.
Phone-as-a-Key (PaaK) is an access technology that turns an authorised smartphone into a digital car key, so drivers can unlock, lock and start a car over encrypted connections without a physical key fob.
How Phone-as-a-Key Works
PaaK systems use short-range wireless standards, mainly Bluetooth Low Energy (BLE), Near Field Communication (NFC) and Ultra-Wideband (UWB), together with cryptographic keys shared between a mobile app and the car's control unit. Other systems send the command over the internet to the manufacturer's connected-car interface. A short-range system typically works like this:
- Digital credential: After a booking, the platform issues a time-limited, cryptographically protected credential to the user's app.
- Proximity detection: As the driver approaches, antennas in the car detect the phone and estimate its distance.
- Authentication: The car's control unit checks the credential and whether it is valid for the current time.
- Command execution: Once validated, the central locking releases and the car can be started.
PaaK vs. Physical Keys in Fleet Operations
With physical keys, a rental operation needs counters, key handovers or key boxes. Digital keys remove these steps:
- Access without opening hours: Renters go straight to the car, with no desk and no queue.
- No key logistics: There is no key to lose, hand over or return.
- Dynamic access control: Digital keys can be extended, transferred or revoked, for example when a booking ends.
Encryption and Underground Car Parks
Such systems typically use symmetric encryption such as AES to protect the data in transit, and asymmetric methods for key exchange and signatures. Systems that work over Bluetooth and store the credential locally can also unlock cars in underground car parks without cellular reception.
Related Terms
Your phone is the key
At DRAIV, cars with instant booking unlock in the app and lock again when you return them. There is no key to collect.
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