When an exchange, broker, or other service asks you to verify control of a Bitcoin address by signing a message, you can do this directly in the BitBoxApp with either a previously used address or a new address. Signing creates a cryptographic signature without sending bitcoin, changing your balance, or paying a network fee.
A valid signature proves control only of the address used to create it. It does not prove your identity or control of other addresses. The requesting service still decides which address types and message-signing formats it accepts.
Choose the correct address
Use the address specified by the requesting service:
- Used address—this is the most common case: Use Used Addresses when the service requires a specific address associated with an earlier deposit or transaction.
- New address: Use New Address when the service lets you provide a new receiving address before it sends bitcoin to your wallet.
Do not substitute another address when the service specifies an exact one. The BitBoxApp signs messages with Native SegWit addresses beginning with bc1q; before you begin, confirm that the requesting service accepts this address type and the BitBoxApp's message-signing format.
Check the complete request before signing
Sign only a message that you understand and expected to receive. Preserve the complete message exactly, including capitalization, punctuation, spaces, and line breaks. Reject the request if the address or message differs from the original request or if anything is unclear. Share the signed result only with the intended recipient because it can link you to the selected address. Never share recovery words, private keys, passwords, an optional passphrase, or a wallet backup.
Open Sign Message
- Open the BitBoxApp.
- In the left sidebar, select the Bitcoin account containing the address you need. If you will use a new address, select the account where you want to receive the bitcoin.
- At the top of the selected account page, select Account Information.
- In the Account Information window, select Sign Message. The Sign Message window opens with the New Address and Used Addresses tabs.
Continue with Used Addresses if the service requires a specific previously used address. Continue with New Address if the service lets you provide a new address.
Sign with a used address
Use this path when the requesting service identifies a specific address associated with an earlier deposit or transaction.
- Select Used Addresses.
- Enter the requested address in the search field at the top of the window, or browse the addresses below it.
- Check both Receive addresses and Change addresses until you find the exact requested address.
- Select the matching address. Its details let you copy the address, sign a message, or open the address in an external block explorer.
- Select Sign message.
- Confirm that the signing window shows the exact requested address, then enter the complete message supplied by the requesting service.
- Continue with Confirm and copy the signature.
You can also reach the same used-address view by selecting View Used Addresses in Account Information. For message signing, use Sign Message → Used Addresses as the primary route.
Sign with a new address
Use this path when the requesting service lets you provide a new receiving address before it sends bitcoin to your wallet.
- Select New Address.
- Review the address selected by the BitBoxApp. If necessary, choose another address from the next 20 unused addresses.
- Enter the complete message supplied by the requesting service.
- Continue with Confirm and copy the signature.
Confirm and copy the signature
The remaining steps are the same for a new or used address:
- Select Sign on device.
- Connect and unlock your BitBox02 if prompted.
- Review the complete Bitcoin address and message on the BitBox02 display.
- Confirm on the BitBox02 only when both match the original request exactly. Otherwise, reject the request.
- After the signature is created, copy the address, original message, and generated signature from the BitBoxApp.
- Provide the requested information exactly as displayed. Do not edit the message or signature.
Message signed
The message is signed when the BitBoxApp displays the selected address, the original message, and the generated signature. The requesting service must still verify and accept the submitted proof.
If something does not work
The used address is not listed
Confirm that you selected the Bitcoin account containing the address. If you have several Bitcoin accounts, check each relevant account separately. If you use an optional passphrase, make sure you opened the intended wallet. Search for the exact address under both Receive addresses and Change addresses.
Do not continue with another address when the requesting service requires a specific one.
The BitBox02 shows different information
Reject the signing request on the device. Return to the BitBoxApp and compare the complete address and message with the original request before trying again.
The signature cannot be verified
Check that the address, message, and signature have not changed. Capitalization, punctuation, spaces, and line breaks are part of the signed message. If all three values are unchanged but the requesting service still rejects the signature, ask whether it supports the address type and message-signing format used by the BitBoxApp.