Printed QR checkpoints were a big step up from the clipboard. But a QR code is just a picture. Photograph it once on day one, and every round after that can be "walked" from the break room, the car or home.
Where printed codes fall short
A picture of a code is the code
Scanning a photo of a QR sticker gives exactly the same result as scanning the sticker. Nothing in the code changes from one scan to the next, so the system can't tell a real visit from a replay.
Location helps, but not everywhere
Comparing the phone's position with the checkpoint's position catches a lot. It works well in a surface lot. Three levels underground, or deep inside a concrete stairwell, the phone often has no reliable position at all, and those are exactly the places a round most needs to reach.
Stickers wear out and move
Paper codes fade, get peeled off, or get stuck back up on the wrong wall after a paint job. A checkpoint that quietly moved twenty metres still looks fine in the report.
How a secure tag works, in plain words
Each ParkCommand checkpoint plate has a secure NFC tag behind it. When an officer holds a phone to the plate, the tag hands over a one-time code made from its own secret key and a counter that goes up by one with every tap.
- Copies don't work. A photo of the plate carries no code. A saved link from an earlier tap has an old counter and is refused.
- Clones don't work. The secret key never leaves the chip, so a copied tag can't produce valid codes.
- No app to install. The tap opens the patrol page in the phone's browser and records the visit, with the officer's name and the exact time.
- Below ground is fine. With no signal, the tap is kept on the phone and sent as soon as it reconnects. Because the counter only climbs, it can't be counted twice.
Each plate also carries a QR code as a backup, checked against the phone's location like before, for the odd phone without NFC.
| Printed QR sticker | Secure NFC checkpoint |
|---|---|
| Same code on every scan | A new signed code on every tap |
| Works from a photo | Needs the real tag, in hand's reach |
| Relies on location underground | Proof comes from the tag itself |
| Fades and peels | Sealed behind a rigid plate |
From checkpoints to rounds
Proof of single visits is the start. Set up a round once: which checkpoints, in what order, on which days and hours. If a round runs late, is only partly walked or is missed, supervisors hear about it within minutes, while there is still time to send someone. Each morning the site gets a short summary by email.
For security companies, it's the report every client has been asking for. For buildings, it's the difference between trusting the patrol and knowing.
