What is “physical layer” encryption?
This is encryption that works at the so-called physical layer, which is the direct interface to the transmission medium, for instance fiber optics. Encryption can and usually should be performed at higher layers too, such as in software on a personal computer. Do not confuse physical layer encryption, which can be done using standard methods such as advanced encryption standard (AES), with physics based encryption such as AlphaEta™. Although AlphaEta™ does encrypt at the physical layer, it also takes advantage of inherent optical noise in the transmitted signal. Thus, it is a physics based physical layer encryption system.
