As computing power continues to increase, previously unbreakable forms of encryption have crumbled. Now, though, we appear to be on the verge of what may be truly unbreakable quantum encryption. It’s possible in the not too distant future no one will be able to spy on a message secured with these advanced methods no matter how long they hammer at it. Researchers are now looking to take things one step further and completely camouflage a message so no one even knows that a message was sent in the first place.
If you can’t even risk an eavesdropper knowing that a message has been sent, let alone what it says, you need a covert communication system. That’s the idea at the heart of a new experiment conducted at the University of Massachusetts. Researchers there have developed a method of using photons to make a message invisible to everyone but the intended recipient.
The covert system relies on a technique called pulse position modulation, which is actually much more simple than you’d expect. It involves dividing a second, minute, or other unit of time into discrete bands, each of which correspond to a different letter or symbol. This code would have to be shared with the intended recipient ahead of time, which is perhaps the most notable flaw with the whole scheme. Once that’s done, through, a series of pulses could be delivered like optical Morse code to convey a message.
Full article: Scientists develop first completely covert communication system with lasers (Extreme Tech)