How a toll lane spots a fake FASTag with no internet

transcript

A cheap RFID writer. A blank sticker. A free ride? The toll lane has no internet. It still catches you.

There are 11.73 crore tags out there. The lane gets about a second per vehicle. And its link might be down. So no lookups.

Every chip has a TID. Set at the factory. Unique. The bank writes the tag ID, the EPC. Then it signs both together, with its private key. Locked in.

The plaza stores NPCI's key, and every bank's certified key. The lane checks the tag's signature against them. Genuine? Barrier up. No network involved. Forged or copied? Pay another way.

Fake one with a cheap writer? You don't have the bank's key. So no valid signature. Rejected. Here's the clever part. Copy a real tag onto a blank chip? The blank chip's TID is different. The signature covers the TID. Rejected.

The signature is bound to one physical chip. And the bank checks it again later, in case a lane didn't.

Full breakdown in the lecture.