A startup idea: face unrecognition
Design a wearable electronic gadget that looks like a veil over your face.

On the inside of the veil, you have an augmented-reality screen with eyes-driven and voice-driven (possibly neural-driven) control. On the outside, the veil shows a generated image of a chosen human face with your own mimics superimposed.

The device could initially look like a ski mask or like oversized sunglasses. Flexible screens could be used too.

The result is that you look sufficiently realistic, your facial expressions are recognizable, your speech and facial communication gestures are unimpeded. And yet, your face - and especially the information about where your eyes are pointing at any given time - is safe from street cameras.

Second phase - a peer-to-peer communication protocol between face veils will enable secure chat with no central server and no possibility of intercepting any messages.

Third phase - "neurolink". Sensors will measure the electromagnetic impulses in the throat muscles and decode them into speech signals. In this way, a person's internal speech could be detected and used for communication. The effect will be that of a direct "telepathic" outgoing text channel - you just say the words in your mind, and the device will read your throat muscles and transmit the message to the recipient. A micro-speaker connected to the skull bone could be used for secure reception of private voice messages.

Phase 3 mostly reproduces the functionality shown in the recent sci-fi movie "ghost in the shell" where the agents can just switch to "mental communication".

Snuff it, big brother.