Because optical signals operate at extremely high frequencies, it is practically infeasible to measure all of their information content. Optical encryption systems attempt leverage this fact in order to achieve extremely fast encryption speeds. However, despite the intense interest in this area in the optics community, to date there has been little contribution to this area from the security and cryptanalysis community.
In this talk, we overview a non-trivial optical encryption system proposed by [R. Menendez et.al. J. Lightwave Technology, 2005] and others. While the scheme has the potential to perform encryption at extremely high speed, we present a cryptanalysis of the system that shows situations in which the key can be learned with only two known plaintexts.