Invite someone to hold a key
Let a partner, a relative or someone you trust hold one of your vault's keys. They make it in Fountain on their own device and add it to the vault themselves, and the key never leaves that device.
1. What you need
- A vault with their slot still open. In the create-vault wizard, set that key's type to Cosigner and choose Invite later. The vault is saved as a draft until their key is in, and a draft can't receive bitcoin yet.
- Their SignBit account, with their email address confirmed and Discoverable by email turned on in Settings, Preferences, under Privacy. It is off by default, so ask them to switch it on first.
- Fountain on their own device. Their key is made there and stays there. Get it from the download page.
2. Invite them
Open the draft vault. On the open slot, choose Invite, type their email address and choose Send invite. The slot now shows that they are invited.
If their account can be found, SignBit emails them and the invite waits on their dashboard. If they don't get the email or can't see the invite, they either have no account yet or have Discoverable by email turned off. For their privacy we don't tell you which, so ask them to check, then invite them again.
3. Accept the invite
This part is for the person you invited. Open the invite email, or sign in to SignBit. Your dashboard shows an Invitation under Needs your attention, with the vault, how many keys it takes and who invited you. Choose View vault. If you weren't expecting it, choose Decline.
4. Make your key in Fountain
On your own device, open Fountain, set a passphrase and create a key with a name you will recognise, such as "Mum's phone". Back it up, either with Settings, Export backup, or by writing down the 24 words, and keep the backup somewhere safe, away from the device. Then, on the key's card, choose Show public key and Export file (.json). Create a vault with Fountain shows each of these screens.
The public key file is safe to share. It can't spend anything, and it is all SignBit ever sees of your key.
5. Add your key to the vault
On the vault page, find your slot and choose Add key. Upload the public key file you just exported. The fingerprint fills in by itself. Check that it matches the one Fountain shows on the key's card, then choose Add key.
6. When every key is in
Once the last key is added, the vault becomes active and gets its receive address and its vault backup. Everyone who holds a key should download the vault backup from the vault page and keep it with their records. It holds no keys, so it can't move anything, but with enough keys it opens the vault in ordinary Bitcoin software, even without SignBit.
Before the vault holds much, each keyholder can choose Verify key on their slot to prove their key can sign. It moves nothing.
7. Changing your mind
Until their key is in, the owner can choose Cancel on the invite. The slot opens again, ready to invite someone else.