GapSign

An air-gap Android wallet that uses Status Keycard over NFC to sign Ethereum transactions without the private key ever touching an internet-connected device.

Requirements

• Android 7.0+ (API 24)
• A Status Keycard with a loaded wallet
• MetaMask Mobile or any wallet that supports UR QR air-gap signing

Getting a release APK

Download the latest APK from Releases and sideload it onto your device.

The APK is built and signed automatically by GitHub Actions on every version tag.

Building from source

Prerequisites

• Node.js 20+
• JDK 17
• Android SDK with NDK 27.1.12297006

Setup

npm install

Run (development)

npm run android

Release build

cd android && ./gradlew assembleRelease

Development

# Lint
npm run lint

# Tests
npm test

Security notes

• Pairing data is stored in encrypted storage (Android Keystore-backed)
• The signing key (Keycard) is never exposed to the app — only the signature result is returned
• QR communication uses the Blockchain Commons UR standard for structured binary data

License

MIT