Need to verify your Bitcoin withdrawal address with an exchange or broker? A Satoshi Test, sometimes called a micro-transaction test, is a common method to confirm ownership of a specific Bitcoin address. This guide will walk you through performing a Satoshi Test using your BitBox hardware wallet and the BitBoxApp, focusing on the crucial step of selecting the correct UTXO (Unspent Transaction Output) with Coin Control.

1. Start your transaction in the BitBoxApp

1. Open the BitBoxApp.
2. In the left sidebar, choose the Bitcoin account that contains the address you need to verify.
3. Click the Send button in the main window. (Note: This button is only active if the account has a Bitcoin balance.)

2. Open the Coin Control panel

4. Once you're in the "Send" interface and Coin Control is enabled, you'll see a Coin control button.
5. Click this button to open the Coin Control panel. This panel lists all available UTXOs for the selected account.

3. Select the correct UTXO: a crucial step

This is the most important part of the Satoshi Test. Selecting the correct UTXO ensures the test transaction originates from the specific address your exchange or broker needs to see.

6. Identify the required UTXO: Carefully review the list in the Coin Control panel. You must find and select the UTXO that corresponds to the exact Bitcoin address your exchange or broker has asked you to verify. If you have previously labeled your addresses or transactions (a recommended practice), this will make identification easier.

7. Important Note: Avoid using UTXOs from “Change Addresses”
   1. While a Satoshi Test transaction sent from a change address might still be technically valid for some exchanges (as it still originates from an address you control), it is strongly not recommended.
   2. Change addresses are internal addresses automatically generated by the BitBoxApp to manage the "leftovers" (the change) from your previous transactions.
   3. These addresses, and the UTXOs associated with them, typically do not appear in your standard transaction history view within the BitBoxApp. They are generally only visible within the Coin Control panel.
   4. The BitBoxApp clearly marks these UTXOs as "change address" in the list.

8. Once you've confidently identified and selected the correct UTXO (from the address your exchange wants to verify, and not a change address), click OK or confirm your selection in the Coin Control panel. The BitBoxApp will now use only your chosen input(s) for this transaction.

4. Enter the recipient address and specific amount

Now, follow the precise instructions provided by your exchange or broker:

9. In the recipient field, carefully enter the Bitcoin address they specified for the test transaction.
10. In the amount field, enter the exact small amount of Bitcoin they require for the test (e.g., 0.00001 BTC). Precision is key here.

5. Verify all details on the BitBoxApp and your BitBox device

Before broadcasting the transaction, meticulously double-check everything:

11. On the BitBoxApp screen: Review the recipient address, the exact amount to be sent, and the estimated transaction fee.
12. On your BitBox hardware wallet: This is your most critical security check. The trusted display on your BitBox device will show the recipient address and the amount. Carefully verify these details on the physical device screen to protect against malware or on-screen errors on your computer.

6. Confirm and send your transaction

If all the information displayed on your BitBox device's screen is accurate:

13. Confirm the transaction on the BitBox hardware wallet itself. This action authorizes and broadcasts your transaction to the Bitcoin network.

You've successfully performed the Satoshi Test! Your exchange should now be able to verify your withdrawal address.