Specter 2/3 PSBT Multi-Sig

Keystone firmware versions V1.1.1 (BTC-Only) or newer support PSBT Multi-signature functions. Detailed instructions below will explain how to create a 2-out-of-3 PSBT Multi-signature wallet with the Keystone Wallet, Coldcard and a SeedPicker as 3 participant co-signers. We will use here Specter V1.4.6 as the watch-only coordinator.

I. Preparation

1. Firmware version V1.1.1 (BTC-Only) or newer running on Keystone Essential or Pro models. Create recovery phrase A.

(Please read How to upgrade firmware for more details.)

2. Coldcard upgraded to firmware version V2.1.0 or newer.

3. http://seedpicker.net/ run on an offline PC/Mac.

3. Specter (V1.4.6 or newer) installed and running on PC/Mac.

4. MicroSD card (≤512GB; default FAT32 format).

pageHow to Format a MicroSD Card to FAT32?

II. Your devices on Specter

Tips: If you want to switch to [Test Net], please go to Keystone > [Settings] > [Blockchain] > [Test Net]. Then continue with the following steps.

1. Adding Keystone to Specter

1) Click [+ Add new device], select your device type [Keystone] , then enter the name.

2) You can add Keystone on Specter by QR code or microSD card.

- By QR code

1) On Keystone: Touch [Menu] > [Multisig Wallet] > Press [•••] icon on the top right > [Show/ Export XPUB].

2) On Specter: Click on [Scan QR Code], then scan the QR code shown on Keystone.

- By microSD card

1) Insert the microSD card into Keystone, then touch [Menu] > [Multisig Wallet] > [Show/ Export XPUB] > [Export All] > [Export].

2) Take out the microSD card from your Keystone and insert it into PC/Mac.

3) On Specter: Click on [Upload from SD Card] > Select and open the .json file exported from Keystone.

4) Click [Continue] to add Keystone.

2. Adding Coldcard on Specter

1) Click [+ Add new device] on Specter, then select your device type [ColdCard] and enter the name.

2) Insert the microSD card into Coldcard > [Settings] > [Multisig Wallets] > [Export XPUB] > Get xpubs from Coldcard.

3) Take out the microSD card from your Coldcard and insert it into PC/Mac.

4) On Specter: Click on [Upload from SD Card], then select and open the .json file exported from Coldcard.

5) Click [Continue] to add Coldcard.

3. Adding Paper Wallet on Specter

By using a software-generated paper wallet, you eliminate the need to buy a third hardware wallet (you may later have to buy a hardware wallet if you need to use this key for emergency recovery purposes).

In this tutorial, we chose to use SeedPicker to generate the third recovery phrase.

Warning: This is the highest risk step in our multisig setup. Follow the instructions closely to drastically improve your security.

1) Insert the microSD card into your PC/Mac.

2) SeedPicker run on an offline PC/Mac, and create a new recovery phrase. Then click [Download] to save the Xpub of the recovery phrase created by SeedPicker as a .json file to the microSD card.

3) Click [+ Add new device] on specter. Select your device type [Other] and enter the name. For this tutorial, we will name the device "Paper Wallet".

4) Click [Upload from SD Card], then select and open the .json file exported from SeedPicker.

5) Click [Continue] to add "Paper Wallet".

III. Creating a watch-only wallet for 2/3 PSBT multisig wallet on Specter

1. Specter > Click [Create Multisignature wallet]. Pick the concerning devices [ColdCard] [Keystone] [Paper Wallet] and click [Continue].

2. Set the Name, Type and number of needed signatures, then click [Create wallet].

3. Create the watch-only wallet for 2/3 PSBT multisig wallet.

IV. Importing the 2/3 PSBT multisig wallet to Keystone

1. On Specter: Select your multisig wallet (e.g. Bob's Multisig Wallet) > Click on [Settings] > [Export] > [Show Keystone QR Code].

2. On Keystone: Touch [Menu] > [Multisig Wallet] > [Import Multisig Wallet] > Touch [Scan] icon > [Understood] > Check the wallet info and touch [Confirm] > Import successful.

V. Importing the 2/3 PSBT multisig wallet to Coldcard

1. Insert the microSD card into PC/Mac.

2. Click on [Save ColdCard file] on Specter to save the .txt file to the microSD card.

3. Take out the microSD card from PC/Mac and insert it into Coldcard.

4. On Coldcard: [Settings] > [Multisig Wallets] > [Import from SD].

5. Select .txt file exported from Specter (e.g.Bob's Multisig Wallet) > Confirm(√) and complete the import of the 2/3 multisig wallet.

VI. Receiving bitcoin to the 2/3 multisig addresses

1. For Keystone, touch [Addresses] to display the receiving addresses.

2. On Specter: Select your multisig wallet (e.g. Bob's Multisig Wallet), then click on the [Receive] tab on the top to display the receiving address.

VII. Sending a 2/3 PSBT multisig transaction

1. Creating an unsigned transaction on Specter

1) On Specter: Select your Multisig Wallet (e.g. Bob's Multisig Wallet) > Click one [Send] > Input the recipient address and amount > [Create unsigned transaction].

2. Signing with Keystone

Tips: You can sign transactions with Keystone by scanning the QR code or by file transfer.

- Option 1: Via QR Code

1) On Specter: Click on [Keystone] > [Sign with QR codes] > Specter displays the unsigned transaction data as a QR code format.

2) On Keystone: Press the [Scan] icon > Scan the QR code shown on Specter interface > [Sign] > Password verification. The device will then show the signed transaction data in QR code format.

3) On Specter: Click on [Scan signed transaction] > Scan the QR code shown on Keystone > Keystone signed successfully.

Tips: If you have difficulty on QR code scanning, please tap the QR code to adjust the size of the QR code on Keystone and retry.

- Option 2: Via File

1) Insert the microSD card into PC/Mac.

2) On Specter: Click on [Keystone] > [Sign with SD Card file] >[Save transaction to file ] > [Save] (save the unsigned transaction file to microSD card).

3) Take out the microSD card from PC/Mac and insert it into Keystone.

4) Press the "microSD card" icon > Select and open the unsigned transaction file > [Sign] > Password verification > press [touch here...] to partially export the signed transaction file to the microSD card.

5) Take out the microSD card from your Keystone and insert it into PC/Mac.

6) On Specter: Click on [Upload the signed transaction] > Select and open the partially signed transaction file exported from Keystone > Keystone signed successfully.

3. Signing with Coldcard

1) Insert the microSD card into PC/Mac > Specter > [ColdCard] > [Sign with SD card file] > [save transaction to file] > [Save] (save the unsigned transaction file to the microSD card).

3) Take out the microSD card from PC/Mac and insert it into your Coldcard.

4) On Coldcard: [Ready To Sign] > [OK] > Export the partially signed transaction file to the microSD card.

5) Take out the microSD card from your Coldcard and insert it into PC/Mac.

6) On Specter: Click on [Load signed transaction] > Select and open the partially signed transaction file exported from Coldcard > Coldcard signed successfully.