  We motivate and develop a new line of digital forensics. In the meanwhile, we
propose a novel approach to photographer identification, a rarely explored
authorship attribution problem. We report a proof-of-concept study, which shows
the feasibility of our method. Our contributions include a new forensic method
for photographer de-anonymization and revealing a novel privacy threat which
had been ignored before. The success of our creation builds on top of a new
optical side-channel which we have discovered, as well as on how to exploit it
effectively. We also make the first attempt to bridge side channels and inverse
problems, two fields that appear to be completely isolated from each other but
have deep connections.
