Say it with your eyes- Encrypted Gaze

I was just thinking about how one might press perfect communication to its limits. If a mental walkie talkie is not on the table, or might be considered too heavy a hand or even just not as much fun in a particular case as something potentially overheard, a system of eye flits can be established. At its core this is simply the method used to assign gaze to letters that is already in place, but this communication method assumes ample time and synchronization, to the point where the chart is overlayed in some sense, whenever the process is initiated. Already in this form this would be hard to eavesdrop on, and feels like it would be a fun way to pass secret messages back and forth.

Not only that, but between the two utilizing it a small space could be set aside mentally to track a caesarian cipher type apparatus in conjunction with the primary chart. At any point a letter might be signaled, a wink made, and then a second letter signaled, pulling each out of their current position on the chart. Assuming this is done and tracked dutifully, even those with clear line of sight would have no hope of deciphering messages to a degree past anything more than their length, uncertain as to how the chart may shift in their absence. Certainly this would be essentially the use of a superpower level of shared perception for a return as simple as communicating in privacy, but something about this kind of body based encryption is tantalizing for me. It also opens up the door for possibilities such as if entire channels of communication (all sight, for example) are externally tapped, that creative methods for adding to the code could be layered in with audible taps, touch, taste, etc., allowing for all manner of point to point communication so that the underlying system can remain stable and secure. Maybe I'm just a nerd on some deep level (certainly I am, in fact), but I like it.