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Air-Gapped Signing

What is Air-Gapped Signing?

Air-gapped signing lets you use a completely offline device as your dedicated transaction signer. Your private keys live on a device that never connects to the internet, while your everyday wallet handles everything else—checking balances, building transactions, and broadcasting to the network.

Communication between devices happens exclusively through QR codes. No Bluetooth, no WiFi, no network connection at all. This provides hardware wallet-level security using devices you already own.

Think of it like this: Your online device is like a bank teller who can see your balance and prepare transactions—but only you (the offline signer) have the key to the vault.

Why Use Air-Gapped Signing?

  • Maximum key isolation: Your private keys exist only on the offline device. Even if your online device is compromised, your keys remain safe.
  • Transaction verification: Every transaction is reviewed on your secure offline device before signing—not on a potentially compromised device.
  • No extra hardware needed: Turn any spare phone or tablet into a dedicated signing device.
  • Protection from phishing: Since your signer never connects to the internet, it can't be tricked into visiting malicious sites or downloading malware.

What You'll Need

To use air-gapped signing, you'll need two devices:

  1. Online device: Your everyday phone or tablet with Voi Wallet installed and internet access

  2. Offline signer: A second device (phone or tablet) that will stay permanently offline

    Tip: An old phone you no longer use makes an excellent signer device. It doesn't need a SIM card or active service.

Setting Up Your Air-Gap Signer

Follow these steps to configure your offline device as an air-gap signer:

  1. Install Voi Wallet on the device you want to use as your signer

  2. Put the device in airplane mode and keep it there permanently

    Important: For maximum security, your signer device should never connect to the internet. Consider disabling WiFi and Bluetooth in the device settings as well.

  3. Open Voi Wallet and go to Settings → Air-Gapped Signing

  4. Tap "Enable Signer Mode" to configure this device as your offline signer

  5. Give your signer a name (e.g., "My Offline Signer") so you can identify it later

  6. Create or import accounts on the signer device

    Note: These are the accounts whose keys will be protected by the air gap. You can create new accounts or import existing ones using your recovery passphrase.

Pairing Accounts with Your Online Wallet

Once your signer is set up, you need to pair its accounts with your everyday wallet so you can view balances and initiate transactions:

  1. On your signer device: Go to Settings → Air-Gapped Signing and tap "Export Accounts" to display a QR code

  2. On your online device: Go to Settings → Air-Gapped Signing and tap "Import from Signer"

  3. Scan the QR code displayed on your signer with your online device's camera

  4. Select which accounts you want to import to your online wallet

Your accounts will now appear in your online wallet as "Air-Gap Signer" accounts. You can view balances and receive funds, but any outgoing transaction will require signing on your offline device.

Signing Transactions

When you need to send funds or interact with a dApp, here's how the signing flow works:

  1. Initiate the transaction on your online device as normal (send VOI, interact with a dApp, etc.)

  2. A QR code appears on your online device containing the unsigned transaction

    Note: For large transactions, you may see an animated QR code. Just keep the camera pointed at it—your signer will automatically capture all the frames.

  3. Open your signer device and tap "Scan Signing Request"

  4. Scan the QR code from your online device

  5. Review the transaction details carefully on your signer. This is your chance to verify what you're actually signing.

  6. Enter your PIN or use biometric authentication to approve

  7. Your signer displays a QR code containing the signed transaction

  8. Scan this QR code with your online device

  9. The transaction is broadcast to the network automatically

Critical: Always verify transaction details on your signer device before approving. Check the recipient address, amount, and any other details. Your signer shows you exactly what you're signing—take the time to review it.

Security Best Practices

Do

  • Keep your signer permanently offline
  • Store your signer in a safe place
  • Review every transaction on the signer
  • Back up your recovery passphrase

Don't

  • Connect your signer to WiFi "just once"
  • Install other apps on your signer
  • Sign without reviewing the details
  • Share your passphrase with anyone

Common Questions

What devices can I use as a signer?

Any iOS or Android phone or tablet can work as a signer. Older devices work great—they just need to run Voi Wallet and have a working camera. The device doesn't need a SIM card or active phone service.

Can I use the same signer with multiple online wallets?

Yes! You can pair your signer's accounts with Voi Wallet on multiple devices. Each online wallet will be able to request signatures, and you can approve or reject each request on your signer.

What if my signer device breaks or is lost?

As long as you have your recovery passphrase backed up, you can set up a new signer on a different device. Import your accounts using the passphrase and re-pair with your online wallet. This is why keeping your passphrase backup secure is critical.

Do I need to keep my signer charged all the time?

No. Since your signer doesn't need to receive notifications or stay connected, you only need to turn it on when you want to sign a transaction. Keep it charged enough to use when needed.

Why do some QR codes animate?

Complex transactions or transaction groups contain more data than fits in a single QR code. The animated QR cycles through multiple frames to transmit all the data. Just keep your camera pointed at it—the app handles the rest automatically.

Is this as secure as a hardware wallet?

Air-gapped signing provides similar security benefits to hardware wallets: your keys are isolated from the internet and transactions must be physically approved on the secure device. The main difference is that hardware wallets have specialized secure elements, while your phone relies on its standard security. For most users, air-gapped signing offers excellent protection.

Need More Help?

If you have additional questions about air-gapped signing, please visit our Support Center or join our Discord community.