Create a vault with Fountain
Set up a 2-of-3 vault in about 15 minutes. You make two keys in Fountain on your own devices, SignBit holds the third, and no single key can move your Bitcoin.
1. What you need
- A SignBit account with a confirmed email address. The vault wizard stays closed until you have clicked the link we sent you.
- Fountain on two different devices, for example your phone and an offline laptop. Get it from the download page.
- Somewhere safe for two backup files, one from each device, kept apart from the devices themselves.
- About 15 minutes.
Never keep both of your keys in the same Fountain. A 2-of-3 vault is built so that no single thing can move your Bitcoin or lose it. If one phone or one computer holds two keys, losing it or having it stolen takes two keys at once. Keep each key somewhere the other is not, such as your phone, an offline laptop, or a device kept at another address.
2. Set a passphrase in Fountain
Open Fountain on your first device, type a passphrase twice and choose Create keystore. The passphrase locks your keys on this device. Nobody can reset it for you, SignBit included, so write it down somewhere safe.
3. Create your first key
Type a name you will recognise later, such as "Phone", and choose Create key. Fountain makes the key with the exact settings a SignBit vault needs, so there is nothing to configure.
4. Back up Fountain
Fountain shows the key's 24 words next. You do not have to write them down, so choose I've backed it up. Your backup is a file instead. Open Settings, choose Export backup, enter your passphrase twice and choose Save backup. The file holds your keys and vaults, encrypted with your passphrase, and restores on any device. Keep it somewhere you trust, away from this device, and make a new one whenever you add a key.
5. Export the public key
On the key's card, choose Show public key, then Export file (.json), and save the file somewhere your browser can reach. The file holds only the public half of the key and its fingerprint. It cannot spend anything, and it is all SignBit ever receives.
6. Make your second key on another device
On your second device, install Fountain and do the same again. Set a passphrase, create a key with a different name such as "Laptop", export its key file, and save its own backup. Keep the two backup files in different places too, so one fire or one burglary cannot take both.
7. Start the vault
In SignBit, open Vaults and choose Create a vault. Give it a name, such as "Family savings", and leave the signing policy at 2-of-3. That means any two of the three keys together can approve a spend, and one key alone never can. Under Who holds the keys, keep SignBit co-signs, then choose Next.
8. Add your first key
On Your key, choose Upload companion key (.json) and pick the file from your first device. The fingerprint and the public key fill in by themselves. You can give the key a name, which only you and your keyholders see. Choose Next.
9. SignBit's key is added for you
The next step is SignBit's own key. It is added automatically, so there is nothing to do here. Choose Next.
10. Add your second key
For the last key, choose Backup key as the key type. Keep Add key now selected, choose Upload companion key (.json) and pick the file from your second device. Choose Next.
If someone else will hold this key instead, such as a partner, choose Cosigner and then Invite later. The vault is saved as a draft, and it gets its address once they have added their key from the vault page.
11. Review and create
The review lists each key by the start of its public key. Check that each one begins with the same characters as the Public key on the matching key in Fountain. If they match, choose Create vault.
12. Keep a copy of the vault
At the top of the vault page, open Vault backup (descriptor) and choose Download backup. Keep the file with your records. Then open the More actions menu, choose Export, and under Recovery plan choose Print / PDF. With the backup and any two of your keys, the vault can be recovered in ordinary Bitcoin software without SignBit, as our guide on recovering without SignBit shows.
13. Check before the first deposit
Your vault page now shows the address to receive Bitcoin. Before you send real money, follow the guide on checking a receive address, so you know the address really belongs to your vault. Then send a small amount first, and the rest once it arrives.