COVID Scanner & QR Processing
Development of a high-performance mobile app for offline validation of digital certificates focusing on data privacy.
- React Native
- Expo
- TypeScript
- Cryptography
The Challenge
During the pandemic, access controls needed to be fast, secure, and reliable. Security personnel were often stationed at entrances without stable internet connections. The challenge was to cryptographically validate digital vaccination certificates (EU DCC) without sending data to a server (Privacy-by-Design), whilst achieving a scan speed of less than 1 second.
The Solution
Development of a mobile app using React Native and Expo that operates entirely active "On-Device".
Technical Details
- Cryptography: Implementation of Public Key Infrastructure (PKI) logic directly within the app. Daily updates of trust lists (public keys of countries) were downloaded in the background so that validation could subsequently be performed offline.
- Camera Optimization: Use of native camera modules to recognize QR codes even in poor lighting conditions or on damaged displays.
- Privacy: No tracking, no cloud storage of scanned data. Everything happens in the device's RAM.
Key Features
- Offline-First: Validation works even in airplane mode.
- Feedback System: Clear visual and haptic feedback for security personnel upon valid/invalid certificates.
- Performance: Cold start of the app in under 2 seconds.
The Result
The app enabled smooth admission control at large events. Due to the Privacy-First approach and Open Source transparency, the solution enjoyed high trust among users and clients.