Dynamic QR Codes
A key that expires while you watch it.
The holder portal mints a cryptographically signed QR code that rotates on a timer you set per site. A screenshot is worthless seconds later, and the reader verifies the signature itself — no network round trip at the door.
A printed QR pass is a key that can be photographed and forwarded to anyone, forever. A dynamic QR is the same convenience with that flaw removed: the code is signed, it rotates on a timer, and the reader refuses one it has already seen.
How it works
The detail that decides whether this survives contact with a real building.
- Rotation
- Refresh interval is set per site and validated against what the readers will accept
- Signature
- Each code carries a per-site signature the reader checks offline
- Replay
- A nonce ledger on the reader refuses a code that has already been used
- Countdown
- The portal shows a circular countdown, so nobody presents a code that is about to die
- Delivery
- Shareable by WhatsApp, email or a link — no app install required
It rotates while the holder watches
The holder portal shows the live code inside a circular countdown ring. When the ring runs out the code is replaced. Nobody presents a code that has already died, and nobody has to guess how long they have.
The reader verifies it offline
Each code carries a signature made with a key held per site. The reader holds that key too, so it checks the signature itself in milliseconds. No round trip to a server, no dependency on the visitor having mobile signal in a basement car park.
Refresh interval is a per-site decision
Ten seconds for a high-assurance site, sixty for one where visitors regularly have patchy signal. The console validates the interval against what the readers at that site will accept, and refuses a setting that would leave phones showing codes the door rejects.
Used once, then dead
The reader keeps a nonce ledger and refuses a code it has already admitted. Even inside its short valid window, a code that has opened a door will not open it a second time.
No app to install
The holder portal is a web page. A visitor receives a link by WhatsApp or email, opens it, and the code is on screen. For a contractor coming once, an app install is a barrier nobody should have to clear.
The QR encoder is ours
The symbol is generated on our own server rather than by a third-party service, so a visitor's access code is never handed to an outside API to be drawn. The encoder was verified module-for-module against a reference implementation across every symbol version before it was allowed near a door.
Where this fits
Visitors, contractors, tenants, delivery drivers, and anyone who should not be issued a card.
Because every channel resolves to the same holder record, this does not have to be the only way in. A person can hold this alongside a card, a PIN and a plate, and the audit trail still reads as one identity.
Questions about dynamic qr codes
What stops someone screenshotting the code and sharing it?
The rotation interval. By the time a screenshot has been sent to someone else, the code it shows has usually already been replaced. The reader also refuses any code it has already admitted, so even a fast forward does not get a second entry.
Does the visitor need mobile signal at the door?
Only enough to load the code before they arrive. Verification happens on the reader against a locally held key, so no data connection is needed at the moment of scanning.
How long is a code valid for?
You set it per site — typically ten to sixty seconds, with a short overlap so a code is never dead before its replacement appears. The console validates the setting against what the readers will actually accept.
Does the visitor need to install an app?
No. The holder portal is a mobile web page, delivered by a WhatsApp or email link.
The other ways in
One access list, one console, one audit trail — whichever of these a person happens to be carrying.
Face Recognition
Walk up, look up, walk through.
UltraPASS-VehicleVehicle Plate Recognition
The car is the credential.
UltraPASS-BioBiometric Access
A credential that cannot be lent.
UltraPASS-DoorNFC, MIFARE & HID Cards
Keep the cards you already issued.
UltraPASS-DoorBluetooth & BLE
The phone stays in the pocket.
UltraPASS-DoorBarcodes & Static Passes
For everything already printed.
UltraPASS-DoorPIN & Keypad
The fallback that always works.
Put dynamic qr codes on your doors
Talk to Patrick about what is already installed and what it would take to move it onto xSERVA.
Book a Demo