Specter 2/2 PSBT Multi-Sig
Keystone firmware versions V1.1.1 (BTC-Only) or newer support PSBT Muti-signature functions. Detailed instructions below will explain how to create a 2-out-of-2 PSBT Multi-signature wallet with the Keystone Wallet and Coldcard as 2 participant co-signers. We will use here Specter V1.4.6 as the watch-only coordinator.
2/2 PSBT Multi-sig is not a good quorum. This tutorial is just for the purpose of showing how to use Keystone and Coldcard to set up your multi-sig wallet with Specter. Learn more about picking a good quorum: https://btcguide.github.io/quorum

I. Preparation

1. Firmware version V1.1.1(BTC-Only) or newer running on Keystone Essential or Pro. Create recovery phrase A.
(Please read How to upgrade firmware for more details.)
2. Coldcard upgraded to firmware version V2.1.0 or later. Create recovery phrase B.
3. Specter (V1.4.6 or later) installed and running on PC/Mac.
4. MicroSD card (≤512GB; Default FAT32 format).

II. Add device on Specter

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

1. Add Keystone on Specter

1) Click [+ Add new device] > Select your device type [Keystone] and enter the name.
2) You can add Keystone on Specter by QR code or microSD card.

- By QR code

① Keystone > [Menu] > [Multisig Wallet] > press [•••] icon on the top right > [Show/ Export XPUB].
② Specter > click [Scan QR Code], then scan the QR code show on Keystone.

- By microSD card

① Insert the microSD card into Keystone > [Menu] > [Multisig Wallet] > [Show/ Export XPUB] > [Export All] > [Export].
② Take out the microSD card from Keystone and insert it into PC/Mac.
③ On Specter: Click on [Upload from SD Card], then select and open the .json file exported from Keystone.
3. Click [Continue], add Keystone successfully.

2. Add Coldcard on Specter

1) Click [+ Add new device] on specter. Select your device type [ColdCard] and enter the name.
2) Insert microSD card into ColdCard > [Settings] > [Multisig Wallets] > [Export XPUB] > Get xpubs from Coldcard.
3) Take out the microSD card from Coldcard and insert it into PC/Mac.
4) On Specter: Click on [Upload from SD Card] > Select and open the .json file exported from Coldcard.
5) Click [Continue], add Coldcard successfully.

III. Create watch-only wallet for 2/2 PSBT multisig wallet on Specter

1. On Specter: Click [Create Multisignature wallet]. Pick the devices [ColdCard] [Keystone] and click [Continue].
2. Set the name, Type and number of needed signatures. Click [Create wallet].
3. Create watch-only wallet for 2/2 PSBT multisig wallet successfully.

IV. Create 2/2 PSBT multisig wallet on Coldcard

1. Insert the microSD card into Coldcard with .json file exported from Keystone in the card.
2. [Settings] > [Multisig Wallets] > [Create Airgapped].
3. Set address type (Default-P2WSH) and the number of cosigner (2 of 2).
4. Confirm (√) and complete creating a 2/2 multisig wallet.
5. You will get a file named “export-CC-2-of-2.txt” on your microSD card after the previous step. You will need it to import multisig wallet to Keystone.
Tips:If you didn’t get the file, please export manually by following instructions:
1. Insert the microSD card into Coldcard.
2. [Settings]> [Multisig Wallets] > [2/2: CC-2-of-2] > [Coldcard Export] > [Coldcard Export] > Export-CC-2-of-2.txt.

V. Import 2/2 PSBT multisig wallet to Keystone

1. Insert the microSD card into Keystone with “export-CC-2-of-2.txt” file exported from Coldcard in the card.
2. [Menu] > [Multisig Wallet] > [Import Multisig Wallet].
3. Select file “export-CC-2-of-2.txt” > [Understood] > Check the wallet Info and touch [Confirm].

VI. Receiving bitcoin to the 2/2 multisig address

1. On Keystone: Touch [Addresses] to display the receiving addresses.
2. On Specter: Select your Multisig Wallet > Click on [Receive] to display the receiving address.

VII. Sending a 2/2 PSBT multisig transaction

1. Create unsigned transaction on Specter

1) On Specter: Select your Multisig Wallet > Click on [Send] > Input the recipient address and amount > [Create unsigned transaction].

2. Sign with Keystone

Tips: You can choose sign the transaction on Keystone via QR code or File.

- 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 density of the QR code and retry.

- By File

① On Specter: Click on [Keystone] > [Sign with SD Card file] > [save transaction to file] > [Save] (save the unsigned transaction file to microSD card).
② Take out the microSD card from PC/Mac and insert it into your Keystone.
③ On Keystone: Press the [microSD card] icon > Select and open the unsigned transaction file > [Sign] > Password verification > Press [touch here...] to export partially signed transaction file to microSD card.
④ Take out the microSD card from your Keystone and insert it into PC/Mac.
⑤ On Specter: Click on [Upload signed transaction] > Select and open the partially signed transaction file exported from Keystone > Keystone signed successfully.

3. Sign with Coldcard

1) Insert the microSD card into PC/Mac.
2) On Specter: Click on [ColdCard] > [Sign with SD card file] > [save transaction to file] > [Save] (save the unsigned transaction file to microSD card).
2) Pull out the microSD card from PC/Mac and insert it into your Coldcard.
3) On Coldcard: [Ready To Sign] > [OK] > export partially signed transaction file to microSD card.
4) Pull out the microSD card from your Coldcard and insert it into PC/Mac.
5) On Specter: Click on [Load signed transaction] > Select and open the partially signed transaction file exported from Coldcard > Coldcard signed successfully.

4. Broadcast transaction on Specter

1) You can choose to broadcast the multisig transaction immediately or later.
Instructions recommended:
Last modified 1mo ago