Compliance

Ensuring compliance will be an important issue in any TDP road-pricing scheme. How do the authorities deal with drivers who disconnect their OBUs? Can clever criminals sell fake OBUs which falsify journeys to drivers?

In the Trusted Driver model, key parts of the algorithm are implemented with cryptographic techniques in a tamper-resistant SIM card within the On-Board Unit. This secures the OBU against fakes and clones. It also ensure that a driver can't cheat by reprogramming his black box. Security is a good as that in other smart-card implementations.

To detect drivers who have switched off their OBUs requires some form of road-side cross-checks. These could either be with automatic number-plate recognition cameras, or RF beacons. The details differ, but these challenge the OBU to prove it is operating honestly.

The response to challenge is a yes or no, and is managed by the trusted cryptographic engine within the OBU. Privacy is maintained: journey history is not leaked by the challenge.

Challenge from Road-Side Beacon