| Abstract: | Described herein are various technologies pertaining to authentication of
integrated circuits by using external factors to affect or modify an
output of a physically unclonable function (PUF) circuit. In an example,
the output of the PUF circuit in response to a challenge signal can be
sensitive to changes in environmental factors. In another example, the
output of the PUF circuit can be sensitive to user-selectable
configuration parameters of the PUF circuit. In yet another example, the
output of the PUF circuit can be modified by additional circuitry
external to the PUF circuit based upon one or more selectable or
configurable inputs. A PUF-based device authentication system that uses
external factors as authentication inputs to affect a challenge response
of the device authentication system can enhance authentication
capabilities by permitting multi-factor authentication. |