[world2vec]

In the sci-fi novel "The Mountain in the Sea" (highly recommended btw) there is a piece of tech called "abglanz" which is an identity shield mask that flickers in iridescent blurry patterns to protect a person's privacy from camera surveillance.

[joshstrange]

I seem to recall a similar device in. “Fall; or, Dodge in Hell”. I think it was a collar-type device you wore but maybe it was closer to a helmet.

[dblangford]

A similar device is central in Philip K Dick's "A Scanner Darkly" too.

[washywashy]

Also gevulot in Quantum Thief - mentioned in nested comment above

[FloayYerBoat]

Similar necklace in Daemon / Freedom by Daniel Swarez.