Inspired by a discussion elsewhere, I've been wondering if the concept of a "trusted device" is considered a factor - on it's own - in multi-factor authentication?
Given context is that a mobile application has signed on to a service that requires authentication. The service will, after login, trust the device from this point. The mobile application can now use the device's own authentication methods (pin-code, password, fingerprint, face recognition) to authenticate the use of the app.
Would the combination of "trusted device" and e.g. fingerprint be recognized as a multi-factor authentication?