With firmware versions V1.3.0 (BTC-Only) or later, you can set Electrum 4.0 or later as a watch-only wallet that functions as the companion app for Cobo Vault Essential or Pro.
Tips: If your Cobo Vault is running firmware version 1.1.0/1.2.0/1.2.1, you can set Electrum 3.3.8 as watch-only wallet. As Electrum has released their 4.0 version which has implemented PSBT (BIP 174) as default protocol, so if your Electrum is running version 4.0 or later, please make sure your Cobo Vault has been updated to V1.3.0(BTC-Only) or later.
Preparation:
1. Firmware version V1.3.0 (BTC-Only) or later running on Cobo Vault Essential or Pro. (Upgrading Firmware)
2. Electrum wallet 4.0 or later version installed on personal computer or smartphone.
3. MicroSD card (FAT32 format, capacity not exceeding 32 GB).
Receiving Assets
1. On Cobo Vault: Touch [Addresses]to display the receiving addresses.
2. On Electrum: Select [Receive]to display receiving addresses (you can set receiving amounts).
Sending Assets
1. Create a Transaction with Electrum
1）Select [Send], choose a receiving address, set the transaction fee, and add a memo if desired.
2）Select [Preview] to view the unsigned transaction data.
2. Sign with Cobo Vault Hardware Wallet
1）Scan unsigned transaction data.
a. Select [Export > For hardware devices; include xpubs > Show as QR code] to display the unsigned transaction data as a QR code.
b. Touch the scanning icon in the top right corner of the Cobo Vault main page and scan the QR code displayed by Electrum.
c. Sign the transaction on Cobo Vault to obtain the signed transaction data.
2）Use a microSD card to transmit unsigned transaction data.
a. In Electrum, select [Export > For hardware devices; include xpubs > Export to file] and export the unsigned transaction data as a .psbt file to your microSD card’s root directory.
b. Inset your microSD card into the Cobo Vault and power on the device. Touch the [MicroSD card] icon, then find and open the unsigned transaction .psbt file.
c. Sign the transaction on Cobo Vault to obtain the signed transaction data.
3. Broadcast with Electrum Wallet
1）Uploading Signed Transaction Data with QR Code
a. In the Electrum menu bar, select [Tools]>[Load transaction]>[From QR code]. Align the QR code displayed on Cobo Vault with the camera.
b. After the QR code is recognized, select [Broadcast] to broadcast the transaction to the blockchain network.
2）Uploading Signed Transaction Data with MicroSD
a. Once you signed the transaction on Cobo Vault, touch [Export] (if the signed transaction displays as QR code, touch [export via micoSD]>[Export]) to export the signed transaction data as a .txt file to your microSD card.
b.Take the microSD out of your Cobo Vault and insert it into your personal computer or smartphone running Electrum.
c. In the Electrum menu bar, select [Tools]>[Load transaction]>[From file], then find the signed transaction file in the microSD card root directory and open it.
d. Once the signed transaction data is uploaded to Electrum, select [Broadcast] to broadcast the transaction to the blockchain network.
Notes:
1. Electrum cannot recognize dynamic QR codes, and static QR codes only have capacity for around 8 inputs, 2 outputs, and the corresponding signing data (capacity may be affected by differences in screen resolution and camera on the device used for Electrum). When transaction data is too large to be transmitted via static QR code and Cobo Vault is unable to recognize or display a QR code, please use your own microSD card to transmit transaction data.
2. Cobo Vault automatically checks and marks the change address for you as a security measure against phishing attacks on Electrum, which may attempt to insert change addresses that do not belong to you. However, these functions only work for the first 100 change addresses Cobo Vault creates by default, and will not continue working for change addresses you create after initializing the device. Later, we will add support for manually adding an unlimited number of change addresses to the list Cobo Vault will check for in Electrum transactions.
