Free-space optical security and encryption is an often-missed area of active and intense research that potentially offers just this: a physical layer of security for anything from biometrics and surveillance inspection, to medical and health monitoring, holographic data storage and a host of other areas. Using the properties of light freely propagating in air, space or a vacuum, free-space optics (FSO) is actually a diverse field with numerous sub-branches. The paper discusses how cryptography could get a boost from photonic technology.