The rise of smartphones has created an interesting phenomenon: #computers communicating optically by scanning barcodes on each other's screens.

This has some interesting #infosec properties:

* Humans can see when communication happens and control which devices are communicating (by pointing them at each other).

* Only a few bytes of data can be exchanged. This limits attack surface: there's no room for a non-trivial attack payload.

* This requires line of sight. No attacks through walls.