Tap to prove you're there.
Most "scan this" experiences are just a link. A QR code or an NFC tag with a plain URL on it can be photographed, forwarded, and reused by anyone who gets a copy, because the code itself carries no proof of the physical tap that revealed it.
Watermelon Auth cards are different: each one is a chip that signs its own tap. Every read is cryptographically bound to that specific card's identity and a counter that only moves forward, so a copied link is worthless the moment the real card is tapped again. What a tap unlocks is scoped, time-bound, and revocable, not a static secret sitting on a piece of plastic.
Verify a tap or batch
Enter a batch or package identifier to open the public verification page, or hold a Watermelon Auth card to the reader for a cryptographic tap check.
What a tap can do
The same underlying tap works two ways, and a given card can be provisioned for either:
- Open something. A tap hands someone a live, temporary view of exactly one thing, for exactly as long as that thing is relevant, to exactly one viewer at a time.
- Do something. A tap triggers a one-time action the moment it happens: log that someone was physically at this spot, register a device, record an answer. No session, no page to keep open; the proof of the tap is the record.
Proven, attested, or asserted
Every claim a Watermelon Auth record makes falls into exactly one of three tiers:
- Proven by cryptography. The tag is authentic, via AES-CMAC and EV2 mutual authentication. Math, independently checkable by anyone.
- Attested by the server. A record is unmodified since it was written, with a timestamp and a recording principal. Append-only; no UPDATE is ever issued to a provenance row.
- Asserted by a person. The narrative content itself: an origin story, a find date, a maker's name. The system records who said it; it cannot verify the story.
Use cases
Identity badges, specimen provenance, and tap-gated access all reuse the same verified tap:
- Staff and member ID badges. Tap a badge; the phone shows a verified, tenant-branded identity page. Proof of who is at the door.
- Specimen and object provenance. Proven authenticity of the tag plus a provenance record of finds, transfers, and attributed sourcing.
- Ops access without another password. Replace a shared basic-auth password on an internal dashboard with a tap, logged to the card that opened it.
QR-seeded Conway preview
This box starts as a QR-seeded pattern for one minute, then evolves slowly using Conway’s Game of Life. If it becomes stable for 30 seconds, it reseeds automatically.
How a tap is checked
The same public verification stack serves both paths:
- NFC tap: /nfc/ proxies to the Watermelon Auth verifier for the tag's e/m crypto payload.
- QR fallback: /verify/<id> opens the public record without the tag present.
- Static JSON record: /verify/data/records/<id>.json
Tap-gated surfaces
Beyond identity and provenance, a tap can open or trigger something else entirely:
- Live tracking for one person or thing during one event
- Proof of presence at a checkpoint, trailhead, or job site
- Feedback tied to a real interaction, scoped to that exact moment
- Device enrollment without a manual pairing code