BlueWallet 2/3 PSBT Multi-sig: BlueWallet + Keystone + ColdCard

Keystone firmware versions V1.1.1 (BTC-Only) or newer support PSBT Muti-signature functions. Detailed instructions below explain how to create a 2-of-3 PSBT Multi-signature wallet with BlueWallet, Keystone and ColdCard as 3 participant co-signers. Bluewallet V6.2.0 (or newer) can and will be used as both a watch-only coordinating wallet and a participant co-signer.

I. Preparation

1. Firmware version V1.1.1 (BTC-Only) or newer running on either a Keystone Essential or Pro.

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

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

3. Smartphone with the BlueWallet V6.2.0 (or newer) downloaded.

4. Log in to your iCloud Drive on an online PC/Mac.

Note: If you are using an Android based system, you can choose alternative cloud storage applications such as Google Drive. We still recommend saving to the local folder on your device, then copying it over with a data cable. This way, the online drive provider won’t see your file or transaction.

5. MicroSD card (≤512GB; Default FAT32 format).

Tip: Keystone can format microSD cards to FAT32. (Tutorial)

II. Creating a 2/3 multisig wallet with BlueWallet, Keystone and ColdCard

1. Export Coldcard’s XPUB to a microSD card

1) Insert the microSD card into your Coldcard.

2) [Settings] > [Multisig Wallets] > [Export XPUB].

3) Confirm(√) to save the XPUB of the recovery phrase as a .json file to the microSD card.

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

5) Log in to your iCloud Drive on an online PC/Mac. Click [Upload] icon > Select the XPUB file of the Coldcard (e.g. ccxp-5271C071.json) in the microSD card and click [Open] > Upload successfully.

2. Creating a 2/3 multisig wallet on BlueWallet

1) Run the BlueWallet app on your smartphone.

2) Go to the wallets interface and touch [Add now] > set [Name] > pick [Vault] > Select [Let's start] to enter the page so you can import the co-signer's XPUB.

3) Select [Vault Key 1] > [Create New]. Press [Done] after safely backing up your recovery phrase. You can see the first Vault Key has been created by BlueWallet.

4) Turn your Keystone on.

5) Keystone: Select [Menu] > [Multisig Wallet] > [•••] button on the top right corner > [ Show/Export XPUB ]. Keystone will show the XPUB in QR code format.

6) BlueWallet: Select [Vault Key 2] > [Import] > [Scan or import file], then use your smartphone's camera to scan the QR code displayed on Keystone. Doing so would successfully import Keystone's XPUB.

7) Select [Vault Key 3] > [Import] > [Scan or import file] , then select the [Files] icon on the bottom left > Find the XPUB file in your iCloud Drive and select it. Doing so would successfully import the Coldcard's XPUB.

8) Select [Create] and the 2/3 multisig wallet would be successfully created.

3. Importing a multisig wallet to Keystone as a co-signer

1) BlueWallet: Go to the corresponding wallet and select the [•••] button on the top right corner, then select the [Export Coordination Setup] option to reveal a dynamic QR code.

2) Keystone: Select [Menu] > [Multisig Wallet] > [Import Multisig Wallet] > then select the [scan] icon on the top right corner and scan the QR code displayed on BlueWallet > select [Confirm] to successfully join the multisig wallet as a co-signer.

III. Receiving bitcoin to the 2/3 multisig address

You can use receiving addresses displayed with either the Keystone or BlueWallet to receive bitcoin.

1. Keystone: Enter the [Multisig Wallet] and select [Addresses] to display the receiving addresses.

2. BlueWallet: Go to the corresponding wallet and select [Receive] to display the receiving address.

IV. Sending bitcoin from the 2/3 multisig wallet

1. Create a 2/3 multisig transaction on BlueWallet

1) Go to the corresponding wallet and select [Send].

2) Configure the receiving address, amount, transaction fees, and notes. Select [Next] and enter the signature page. You can see the first signature has been automatically signed by BlueWallet.