Signing a message is a powerful cryptographic function that allows you to prove you own a specific Bitcoin address without having to make a transaction. You can sign any piece of text with your private key, creating a unique digital signature. Anyone who has your public address and the signature can then verify that the message could only have been signed by the owner of that address.

This guide will show you how to securely sign a message using Electrum and your BitBox02.

Before you begin:

• Please ensure your BitBox02 is fully set up and updated to the latest firmware using the BitBoxApp, and have the device ready to connect and unlock when prompted for secure actions.
• The latest version of Electrum (https://electrum.org) must be installed on your computer.
• You must have already connected your BitBox02 to Electrum. If not, please follow our connection guide (How to connect your BitBox02 with Electrum) first.

Step-by-step guide to signing a message:

You can prove ownership of a Bitcoin address by signing a message with it.

1. Go to the Addresses tab. If you don't see it, enable it via the menu View > Show Addresses.

2. Right-click the address you want to use and select Sign/verify message.

3. Enter the message you wish to sign and click "Sign".
4. Check the message on your BitBox02's screen, and then confirm it on the device.
5. Copy the generated signature from Electrum to provide proof of ownership.

FAQ Section:

What is a common use case for signing a message?

Signing a message is often used to prove ownership of funds. For example, a cryptocurrency exchange might ask you to sign a specific message to verify that the withdrawal address you provided is truly yours before they process a large transaction.

Is signing a message a transaction? Does it cost anything?

No, signing a message is not a Bitcoin transaction. It does not get recorded on the blockchain and does not require any network fees. It is a purely offline mathematical operation between your private key and the message text.