Connected synthetic physically unclonable function

A PUF circuit comprising one or more imaging sensors, the PUF circuit comprising a processor configured to receive information about a subset of sensor pixels of an image sensor, the PUF circuit being configured to apply one or more challenges to the subset of sensor pixels under spatially uniform conditions, the PUF circuit comprising a receiver configured to receive output signal values from the subset of sensor pixels, in response to a challenge applied to said subset of sensor pixels, wherein the PUF circuit comprises a bidirectional data communication channel, and the PUF circuit is configured to:

• determine one or more statistical moments of a noise distribution of said output signal values;
• further receive input data IN through said data communication channel from one or more external data sources using the data communication channel, said data IN relating to an external environment in which the PUF circuit is used;
• determine a PUF response R from said one or more statistical moments and said selected input data IN received from said one or more external data sources, said response being a digital signature, wherein the input Data IN are used to handle of the PUF circuit,
• wherein the PUF circuit is further configured to communicate data OUT to one or more external entities using said data communication channel, the data OUT being related to internal information of the circuit;
• and wherein said communicated data OUT is configured to modify an applied challenge C.