Photonic cables were used to transmit information and files between sources. Atour Riten used one to control a droid's personality substrate.
Riten inserted a photonic cable into his librarian droid Persee to download a program from his datastick that disabled its spyware which required the droid to monitor its work environment and to report any activities that might be remotely illegal according to Imperial statutes, as well as alter its basic loyalty module by placing Atour at the top of its function pyramid rather than the Empire.
After insertion and rotation of the cable, Persee would keep to itself while around its master. Any tampering of its memory chip to bypass the new programming would result in a complete memory wipe, all the way down to the primary nodes, rendering the droid useless. Even if Persee was under duress for answers, it would suffer a firmware breakdown and there would be no indication of sedation.