The plugin functions by establishing a connection to the Signet client which communicates with the Signet USB device to help fill web forms on the pages you visit as well as log you into websites. When a new page is loaded the extension sends information about that page to the Signet client which searches your Signet device's database for any data that can be used to fill out web forms on the page. If any matching data is available pressing the Signet plugin button will request it from the Signet device. When you confirm the request by pressing the Signet device button the data will be entered into your browser. By sending only the requested data to the browser and doing so only when the Signet device's button is pressed your data is less vulnerable even on an insecure system.