Is Fast Signature safe?

Fast Signature relays eFast signing requests and active-tab IDs to a local native messaging host.

On configured eFast and DFAST signing pages, Fast Signature listens for page events such as FAST_signPES, FAST_signPKCS7, and certificate-signing requests. It forwards the event details, plus the active tab and window IDs, to the local fast.sign.web.extension native host and sends native-host responses back to parapheur tabs.