Polkadot Ledger Offline Signer

Single-file airgapped transaction signer for Polkadot/Kusama.

Features

• Airgapped: Webcam QR in → QR out, no USB/clipboard needed
• Self-Contained: Single 938KB HTML file, works completely offline
• Ledger Compatible: BIP32-Ed25519, Legacy + Generic derivation modes

Security

The tool will NOT work unless:

1. ✓ Opened as local file (file:// protocol)
2. ✓ Internet is disconnected (offline mode)

Recommended Setup:

1. Download index.html to USB stick
2. Boot Tails OS from USB
3. Disconnect all network (WiFi + ethernet)
4. Open the HTML file in Tails browser
5. The tool will verify you're offline before showing the form

Minimum Setup:

1. Save index.html to your computer
2. Disconnect from internet completely
3. Open the file directly (file://)
4. Red security warning will block usage if online

Usage

Airgapped Workflow:

1. Online: Create extrinstic → Show QR (papi.how)
2. Offline: Scan QR → Sign TX → Show QR
3. Online: Scan QR → Broadcast(pjs/curl rpc)

Manual Workflow:

1. Online: Copy unsigned TX hex
2. Offline: Paste → Sign → Copy signed hex
3. Online: Paste → Broadcast

Technical

Derivation: BIP32-Ed25519 (Ledger compatible) Paths: Legacy m/44'/434'/0'/0'/0' | Generic m/44'/434'/0'/0/0 Networks: Kusama (434) | Polkadot (354) Signing: Ed25519 via @noble/ed25519

Build

npm install && npm run build

Deploy

Auto-deploys to GitHub Pages + IPFS on push to master.

Setup:

# Add Pinata JWT secret
gh secret set API_JWT --body "eyJhbGc..."

# Enable IPFS deployment
gh variable set ENABLE_IPFS_DEPLOY --body "true"

# Enable GitHub Pages: Settings → Pages → Source: GitHub Actions

License

Apache-2.0