QR codes can be copied – I built a way to stop reuse
QR codes are convenient, but they have a fundamental weakness:
they can be easily reused by copying or taking screenshots.
To solve this, I built a system that does not change the QR code itself,
but dynamically controls the meaning and validity of the scan result on the server side.
With the same QR code, it is possible to enforce:
• One-time use
• Time-based expiration
In other words, the QR code remains the same,
but reuse can be prevented.
For example, instead of generating multiple QR codes,
a single QR code can be used to control multiple products or items.
Here is a live demo (30 seconds):
https://dynokey.ngrok.app/
The first scan works, and the second scan is blocked.
This approach can be applied to ticketing, access control, authentication, and more.
Patent pending.
If this is useful, feel free to reach out:
[email protected]
Feedback is also welcome.
2 comments
Interesting approach. We're working on a similar problem from a different angle — cryptographic signing (ECDSA-P256) per QR code rather than server-side invalidation, plus geospatial binding and a transparency log. Open source: https://github.com/qrauth-io/qrauth
Happy to answer any questions.