OpenStampsfor industry

Co-presence · not plot location

Phone Sync

Two devices show they were in the same room: this screen shows a code that changes every second, and the other phone's camera reads it. That is co-presence, not EUDR plot geolocation — plot coordinates stay a declared field. Harder to fake from a distance than a typed coordinate; never un-spoofable. This is not the phone witness on Stamp & verify, which signs the file bytes as they are sealed.

Scan, then point

The changing code — hold the other phone's camera up to it
2 · Then point its camera at this one. It changes every second — that is what makes a photograph useless.
  1. Scan the first code with your phone and open the link.
  2. Allow the camera when asked, then point the phone at the changing code. Nothing to press.
  3. Done — the phone shows the result, and this screen shows what the phone reported when the relay is on this host. It is a finding about the two devices, not about a place.
Scanned it and nothing happened? copy or paste the link

Point this camera at the changing code

Fill the frame with the code and hold steady. It reads on its own.

Session … · this device …

What this shows

  • It shows one device's camera saw the other's screen change, live, in the same room — and makes faking that from a distance expensive.
  • It does not prove forest plot geolocation or that GNSS was honest. EUDR plot coords stay a declared field.
  • It is not un-spoofable. A live video call pointed at the screen carries the changing code into another room. Harder than typing a lat/lon — never absolute.
Why a relay defeats it

The code changes about once a second, and the reader must catch several in a row. That is exactly what a still photograph cannot supply — but a live video stream of the screen supplies it to a camera anywhere. A relay attacker is not stopped, only made to work in real time. The ultrasound channel this page also carries (not offered here) is weaker still: sound is about a million times slower than a radio link, so the attacker has a lot of slack. Hardware time-of-flight (UWB) is the stronger answer, and it needs a native app on both devices.