This guide explains how to sign a Bitcoin message with a specific address using Electrum and your BitBox02. The exact message is normally supplied by the exchange, broker, or service requesting proof of address control. Do not create your own message unless the requesting party explicitly asks you to do so.
A valid signature demonstrates control of the selected address. It does not prove someone’s identity or control of other addresses. Signing a message does not create a Bitcoin transaction, move bitcoin, or incur a network fee. The BitBox02 creates the signature while the private keys remain on the device.
Sign directly in the BitBoxApp
You can sign Bitcoin messages directly in the BitBoxApp without installing another wallet application or connecting your BitBox02 to one:
- No specific previously used address is required: Sign a Bitcoin message with a new address on your BitBox02.
- A specific address that has already received or sent bitcoin is required: Sign a Bitcoin message with a used address on your BitBox02.
The BitBoxApp supports message signing with Native SegWit addresses beginning with bc1q. If you specifically want or need to use Electrum, continue below.
Before you begin
- Install the current Electrum release from the official Electrum download page.
- Set up your BitBox02 and install the latest available firmware through the BitBoxApp.
- Have the exact address and message supplied by the exchange, broker, or service ready. Do not compose a replacement message yourself.
- Close the BitBoxApp completely before opening Electrum. Only one wallet application can communicate with the BitBox02 at a time.
- Make sure the required BitBox Bitcoin account is connected to Electrum. If it is not, follow How to connect your BitBox02 with Electrum.
Use the correct Bitcoin account in Electrum
Connecting your BitBox02 to Electrum does not load the complete BitBox wallet with all of its Bitcoin accounts. When an Electrum wallet is created, the selected hardware-device keystore and derivation path determine which BitBox Bitcoin account it represents.
The address you need to sign with must belong to that selected Bitcoin account. In the procedure below, open the Electrum wallet created for the account containing the requested address. If that account has not been connected to Electrum yet, connect it before continuing.
Check the complete request before signing
Only sign a message that you understand and expected to receive from the requesting exchange, broker, or service. The signature may be used as evidence that you control the selected Bitcoin address. Confirm only when the address and complete message shown on your BitBox02 exactly match the request. Reject the request if anything differs or is unclear. Never share recovery words, private keys, passwords, passphrases, or a wallet backup.
Sign the message with Electrum and BitBox02
- Open the Electrum wallet for the BitBox Bitcoin account containing the requested address.
- Open the Addresses tab. If it is not visible, select View → Show Addresses.
- Find the exact address you were asked to use within that account. Right-click it and select Sign/verify message. Do not select a different address merely to continue: a signature proves control only of the address used to create it.
- Confirm that the Address field contains the exact requested address.
- Enter the exact message supplied by the requesting exchange, broker, or service in the Message field. Do not create your own message or change its spelling, capitalization, punctuation, line breaks, or spacing.
- Select Sign.
- Connect and unlock your BitBox02 if prompted.
- Review the address and complete message on the BitBox02 display. Confirm on the device only if both exactly match the original request.
- Electrum displays the generated signature in the Signature field.
- Select Verify. Continue only when Electrum displays Signature verified.
- Copy the address, original message, and signature and provide all three exactly as displayed to the party requesting proof of address control. Changing any part can cause verification to fail.
Signature verified
The procedure is complete when Electrum verifies the signature for the exact address and message you used. This confirms that the signature is mathematically valid. The requesting service still decides whether the address and signing format meet its requirements.
If something does not work
The requested address is not listed
Electrum shows only the addresses from the BitBox Bitcoin account selected when the Electrum wallet was created, not every account in the BitBox wallet. Confirm which BitBox Bitcoin account contains the requested address and then:
- Open the Electrum wallet created for that account, or connect that account to Electrum using the corresponding derivation path.
- Check both receiving and change addresses within that account.
- If you use an optional passphrase, make sure the account was connected using the intended passphrase wallet.
Do not sign with another address if the exchange, broker, or service requires a specific one.
Electrum cannot sign with the address
If Electrum reports that the address is not in the wallet or that it cannot sign messages with this address type, do not substitute another address when a specific address was requested. Confirm the required address and supported signing format with the requesting service.
Electrum does not detect the BitBox02
Close the BitBoxApp completely, reconnect and unlock your BitBox02, and try again. If Electrum still cannot connect, follow How to connect your BitBox02 with Electrum.
The signature cannot be verified
Check that the address, message, and signature are unchanged. Capitalization, punctuation, spaces, and line breaks are part of the signed message. If Electrum verifies the signature but the requesting service rejects it, confirm that the service supports the address type and message-signing format you used.