Cobo Vault firmware version V1.3.0 (BTC-Only) supports PSBT Muti-signature function. This instruction will show how to create a 2/2 PSBT Multi-signature with Cobo Vault, Coldcard and Electrum 4.0 in details.
Preperation:
1. Cobo Vault Essential or Pro upgraded to firmware version v1.3.0（BTC-only）or later
2. Coldcard upgraded to firmware version v2.1.0 or later
3. MicroSD card（≤32GB；default FAT32 format）
4. Electrum Wallet (v4.0.2 or later) running on PC/Mac
*Tips: If you want to switch to [Test Net], please go to "Cobo Vault > Settings > Blockchain > Test Net" and "Coldcard > Settings > Blockchain > Test Net". Then continue with the following steps.
Create a 2/2 multisig wallet with Cobo Vault and Coldcard
- Create multisig wallet on Coldcard
1. Export Cobo Vault’s Xpub to microSD card
1) Insert the microSD card into Cobo Vault
2) Menu > Multisig Wallet > press the [•••] button on the top right > Show/Export XPUB
3) Export All > Export
2. Create multisig wallet on Coldcard
1) Insert the microSD card into Coldcard
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
3. After the previous steps, you will get 2 files on your microSD card
1) “export-CC-2-of-2.txt” - this is for importing multi-sig wallet to Cobo Vault - allows Cobo Vault to check the genuinity of multisig when signing.
2) “el-CC-2-of-2.json” - this is for creating watch-only wallet on Electrum
Tips: If you didn’t get these two files, please export manually by following instructions:
1) Export the multisig wallet file(for importing multisig wallet to Cobo Vault) to the microSD card
① Insert the microSD card into Coldcard
② Settings > Multisig Wallets > 2/2: CC-2-of-2 > Coldcard Export > “export-CC-2-of-2.txt”
2) Export the multisig wallet file(for creating watch-only wallet on Electrum) to the microSD card
① Insert the microSD card into Coldcard
② Settings > Multisig Wallets > 2/2: CC-2-of-2 > Electrum Export > “el-CC-2-of-2.json”
- Import multisig wallet file to Cobo Vault
1. Insert the microSD card into Cobo Vault
2. Menu > Multisig Wallets > Import Multisig Wallet
3. Select file “export-CC-2-of-2.txt” > Confirm
- Import multisig wallet file to Electrum and create watch-only wallet
1. Insert the microSD card into PC/Mac
2. Run Electrum. Choose...> Select file “el-CC-2-of-2.json” > Open > Next > No
Note: As Electrum doesn’t have a Cobo Vault plugin (we are working on that), Cobo Vault can’t generate a Electrum skeleton json file. So you have to export the Electrum skeleton json file from Coldcard to set up the watch-only wallet on Electrum.
Sending bitcoin from the 2/2 multisig address (Cobo Vault & Coldcard)
- Generate multisig transaction on watch-only wallet(Electrum) and export unsigned multisig transaction file to microSD card.
1. Send > Enter destination address and amount > Pay > Send
2. Export > For hardware device; include xpubs > Export for file > Save
- Partially sign multisig transaction on Coldcard
1. Insert the microSD card into Coldcard
2. Ready To Sign > Select transaction file
3. Confirm and export partially signed multisig transaction file to microSD card
- Complete sign multisig transation on Cobo Vault
1. Insert the microSD card into Cobo Vault
2. Enter Multisig Wallet > Press microSD card ICON on the top riight > Select the partially signed transaction file
3. Sign > Password Verification > Export fully signed multisig transaction file to the microSD card
- Broadcast multisig transaction with Electrum
1. Tools > Load transaction > From file > Select fully signed multisig transaction file > Open > Broadcast
