Some exchanges or brokers ask you to sign a specific message before they allow withdrawals to your Bitcoin address. You need a simple way to create this cryptographic proof while keeping your private keys on the BitBox02.

Before you start

• Ensure both Sparrow Wallet and your BitBox02 firmware are up to date.
• Close any other applications (like the BitBoxApp) that might be connected to your BitBox02 to prevent connection issues.
• Import your BitBox02 wallet into Sparrow. If you have not done this yet, follow the article Peek into Bitcoin internals using Sparrow Wallet with your BitBox02.
• Have the exact Bitcoin address and message provided by the service ready. Do not change them.

Example address and message for this guide

• Address: bc1qem7905mz8az5uhzt8yw6yg789m75ssvxk52e9d
• Message: I confirm that I am the sole owner of this Bitcoin address. Order reference 1bd973455f.

Step 1: Open the signing tool

There are two ways to open the message signing tool.

Method 1: From the top menu

1. Open Sparrow Wallet.
2. In the top menu, choose Tools → Sign/Verify Message (or press the shortcut shown).

Method 2: From the Addresses tab

1. In the left sidebar, go to the Addresses tab.
2. Find the address you want to use, right-click it (or click the pen icon) and choose Sign/Verify Message.
   The signing window opens with the address already filled in.

Step 2: Enter the details

5. If needed, paste your Bitcoin address into the Address field.
6. Paste the exact message into the Message field.
7. Ensure Format is set to Standard (Electrum) unless the service asks for another format.
8. Click Sign.

Step 3: Confirm on your BitBox02

8. Select your BitBox02 from the list of connected hardware wallets.
   1. If you see an error, close the BitBoxApp and click Rescan.

9. Unlock the BitBox02 if prompted.
10. The device shows:
    1. Coin: Bitcoin
    2. The address you are verifying
    3. The message to be signed.
11. Check every detail carefully, then confirm on the BitBox02.

Step 4: Copy and share the signature

13. Sparrow now fills the Signature field with a long string.
14. Click Verify to check that Sparrow shows Verification succeeded, then click OK.
15. Right-click inside the Signature field and choose Copy.

16. Send this signature unchanged to the service that requested it.

Further reading

For more information on using BitBox02 with Sparrow Wallet and related topics, see our blog articles:

• How to create a Multi-Signature Wallet with Sparrow and your BitBox02 
• AOP protocol: Making self custody easier