Legacy Multisignature

Legacy Multisignature is the classic bitcoin multisignature wallet: any K of the N members can sign a payment together. Every member is an equal signer, the owner included. In the app the group type is called Legacy Multi-Signature Wallet.

Use it when nobody should be able to pay alone, or when you need a multisignature wallet that follows the long-established standards, for example to work with other software or with existing procedures. Delegated Multisignature costs less in fees and shows less on the blockchain, but there the owner can always pay alone.

Addresses	SegWit P2SH-P2WSH (they start with 3; with 2 on the test networks)
Members	Up to 16, the owner included. K can be anything from 1 to all of them
Keys	BIP48, from each member’s own wallet, sorted as in BIP67
Descriptor	sh(wsh(sortedmulti(K, ...))), shown by the app so other wallets can import the group
Signing	PSBT (BIP174)

In this guide Alice, Bob and Carol share the wallet Company treasury. Any two of the three can approve a payment.

Before you start

• You are logged in.
• Every person you want in the group is an accepted contact.

1. Create the group and invite the members (owner)

1. Open Online → Smart Groups and click Create Group. Choose the type Legacy Multi-Signature Wallet, type a name and click Create.

   

2. Open the group. Click Add a contact for each member. Set the minimum amount of users to approve a spend: this is the K of “K of N”. You count as one of the N.

   Then click Send invitation to group members.

   

2. Accept the invitation (each member)

Open Online → Smart Groups in your own wallet and click Accept Invitation on the group’s row.

On accepting, your wallet sends the owner the public keys the group needs. No private key ever leaves a member’s wallet.

3. Activate the group (owner)

When every member has accepted, open the group and click Activate Group.

The group now has two more tabs: Wallet Balance and Signatures.

4. Receive

Open the group’s Wallet Balance tab. It shows the receiving address of the group, as text and as a QR code. Give it to whoever pays the group.

After a payment, click Update Balance. The page shows the balance and one line per payment, and the group moves to a new receiving address.

Every member sees the same wallet in their own Wallet Balance tab.

5. Start a payment (the first signer)

Any member can start a payment.

1. In the Wallet Balance tab click Send.

2. Type the amount, the address to pay and a description. The description is what the other members will see, so say what the payment is for. Click Next.

   

3. Choose the fee: one of the estimated levels in Select Fee, or tick Manually select Fee and type your own. This is the calculated fee.

4. Optional: tick up to three extra fee options. Each one is a percentage above the calculated fee: +10%, +20% and so on up to +100%.

   The members may sign hours or days apart, and by the time the last one signs the network may ask for a higher fee. With these options the last signer can pay more without starting again. You and every following signer sign all the options; only one is ever sent.

   Click Send Coins.

   

5. Type your wallet password and click Confirm. Your signature is made now.

   

6. The app shows Signature added: your signature was added and forwarded to the other signers. Nothing has been sent to the bitcoin network yet: the payment waits for the other signatures.

The payment is now in the Signatures tab, with your signature and Fully signed still empty:

If the minimum of the group is 1, there is nothing to wait for: you see no extra options, and your own signature sends the payment.

A payment can use coins of several addresses of the group (the group moves to a new receiving address after each payment it receives, and the change of a payment goes to a change address of the group): every member signs each coin with the right key.

6. Sign the payment (each following signer)

1. Open your wallet, open the group and go to the Signatures tab. The payment is there with its description, who signed it, the amount and the address. Click Sign transaction.

   

2. Check the payment: amount, address, description and fee. They cannot be changed. If it is what you agreed to, click Next.

   

3. What happens next depends on how many signatures are still missing:

   • More signatures are needed after yours. The window lists the fee options the first signer set. You choose nothing: click Send Coins.
   • Yours is the last signature. Choose the Fee to pay: the calculated fee, or one of the higher options if the network is busy. Click Send Coins. You sign only that transaction.

   

4. Type your wallet password and click Confirm. Your signature is made now: the payment goes on to the next signer, or, if yours was the last one, it is sent to the bitcoin network.

When the last needed signature is added, the app shows Transaction broadcast: the payment has been sent to the bitcoin network with the fee the last signer chose. The Signatures tab shows it as Fully signed.

If more signatures are still needed (a 3-of-5 group, for example), your signature is added and the payment goes on to the next signer in the same way.

After Update Balance, the Wallet Balance tab shows the new balance of the group:

7. See the group in another wallet (descriptors)

A descriptor is a standard text that describes all the addresses of a wallet. With the two descriptors of the group, any wallet that understands descriptors (Bitcoin Core or Sparrow, for example) shows the same addresses and the same coins, without our software.

1. In the Wallet Balance tab click Descriptors.

   

2. Copy the two texts: one for the receiving addresses, one for the change addresses.

   

3. Import them in the other wallet. In Bitcoin Core, in a wallet created without private keys:

   importdescriptors '[{"desc":"<receiving descriptor>","timestamp":"now","range":[0,100],"active":true,"internal":false},{"desc":"<change descriptor>","timestamp":"now","range":[0,100],"active":true,"internal":true}]'

The descriptors hold only public keys: whoever has them can watch the group, never spend from it. They do show every address of the group, so share them only with people who may see its balance.

Good to know

• Signers do not have to be connected at the same time. A payment to sign arrives when the member opens their wallet. If it is not in the Signatures tab yet, go back to the wallets page and open the wallet again a little later.
• Check before you sign. Sign only what you agreed to.
• Backups. Each member’s keys for the group come from their own wallet. A member who restores their wallet from their words, or through a Consensus Backup, can sign again.
• Do not lose too many members. If fewer than the minimum can still sign, the money is locked. Choose N and K with that in mind: 2-of-3 survives the loss of one member, 3-of-5 the loss of two.