TL;DR
Put each 24-word seed on a stainless steel or titanium plate, check it against the device, and plan three separate places that can’t disappear in the same event.
What you need
- The three seeds on paper from step 4
- Three metal backups
- Three small airtight boxes with silica gel
Paper burns and goes soft when it gets damp. Stainless steel comes through a normal house fire. Set aside an afternoon for this.
Steps
- Transfer the words to the plate, in order. Only the first four letters of each word are needed: in the BIP39 word list, the first four letters are unique.
- Check the plate against the paper, word by word, number by number.
- Now check the plate against the device itself. Trezor: Check Backup in Trezor Suite, you enter the words on the touchscreen. Ledger: the Recovery Check app, installed through Ledger Wallet. BitBox02: Settings → Manage device → Backups → Show recovery words and compare them with your plate. In all three cases the words never touch the computer.
- Once the plate is checked, destroy the paper card. Burn it, don’t just tear it up.
- Put each plate in its own airtight box with a sachet of silica gel. If you use a passphrase, add a copy of it on a separate card or plate, never on the same plate as the words.
- Keep the boxes nearby until step 10, because you’ll check them again there. After that they go to their three places.
What I do on top
Tile-style plates, the ones with loose letter tiles, can lose a tile or have one slip. That gives you the right words in the wrong order, which is worse than unreadable. So each of my boxes also holds a second, engraved plate with the same words. An engraved plate fails differently: the order can’t shift. A rotary tool with a carbide bit does it on stainless steel. Both plates are the same key, so they stay together.
The boxes
- Use a plain box. One that looks valuable gets opened.
- Don’t fill it with resin or glue. A thief just takes the whole thing, and you can no longer check your own backup.
- Don’t put a brand name or device name on the plate. The link between device and plate goes on the printed sheet from step 7.
- Never write down anywhere digital where your seeds are. Not in a notes app, not in a wiki.
One seed per place
Two seeds in one place that burns down leaves you with one seed, and one seed can’t move a 2-of-3 wallet.
Common mistakes
- Aluminium or brass plates. They melt in a house fire.
- Checking the plate against the paper only, not against the device.
- Putting two boxes “temporarily” in the same drawer and leaving them there.