INTRODUCTION

Hardware wallets are good, but a true air-gapped computer that never touches the internet is better. This guide shows you how to turn a Raspberry Pi Zero into a dedicated signing device for your Bitcoin/Monero keys.

PREREQUISITES

• Raspberry Pi Zero (No WiFi/Bluetooth model).
• MicroSD Card.
• USB Camera (for QR codes).
• Screen (optional, but recommended).

INSTRUCTIONS

1. Prepare OS

Download a minimal Linux distro like Alpine or a specialized OS like Seedsigner. Flash it to the SD card.

2. Generate Seed

Boot the Pi. Since it has no network hardware, it is physically impossible for it to leak data online. Generate your 24-word seed phrase using high-entropy dice rolls (don't trust the internal RNG).

3. Signing Transactions

On your online "Watch-Only" wallet (like Electrum or Sparrow), create a transaction. It will generate a QR code.

Scan this QR code with your air-gapped Pi. The Pi signs the transaction with your private key and displays a signed QR code.

Scan the signed QR code back to your online computer to broadcast it.

CONCLUSION

Your private keys have never touched an internet-connected device. This is the highest level of security possible for digital assets.