The hardware wallet, equipped with a camera, scans the QR code to retrieve the data and confirm the signature, and finally, the client scans the QR code displayed on the hardware wallet. The hardware wallet, equipped with a camera, scans the QR code to retrieve the data and confirm the signature, and finally, the client scans the QR code displayed on the hardware wallet. Besides attack surfaces exposed during communication, some hardware wallets also provide firmware update interfaces (commonly via USB, Bluetooth, or SD card mode).