⚠️ This series was written long before COLDCARD's catastrophic seed generation bug was exploited in 2026. It uses a COLDCARD as one of the three signers. Do not use COLDCARD, here or anywhere else. A firmware bug that went unnoticed from 2021 until July 2026 made seeds generated on COLDCARD devices weak enough to guess, and attackers used it to steal more than 1,800 BTC (Coinkite's advisory, more detail). Use Passport Prime in its place, and where this series shows COLDCARD steps, follow the Passport Prime documentation instead.
If one of your multisig signers was created on a COLDCARD, treat that key as compromised. Your funds are then only as safe as your other keys, so set up a new multisig with a replacement signer and move your funds to it.
Disclosure: I work at Foundation, the company that makes Passport Prime.
Seed Signer Parts List
| Item | Purpose |
|---|---|
| Raspberry Pi Zero 1.3 (pre-soldered) | To build seed signer |
| 1.3 inch LCD hat screen | To build seed signer |
| Camera Adapter | To build seed signer |
| Camera | To build seed signer |
| Case | Self print or buy from here or Crypto Cloaks |
| Micro SD Card | For seed signer OS |
| 4x Spacers | To build seed signer |
| 4x M2.5 Pan Head Screws - 6mm | To build seed signer |
| 4x M2.5 Pan Head Screws - 12mm | To build seed signer |
Got everything you need? Lets get started with the software setup.