There's this science fiction book, and I'm blanking on the name of it right off hand, but there's a harvester that attached itself to Ceres, the asteroid, and made octagonal solar shades to freeze the Earth.

The reason I bring it up is because if they detected radio signals too close to them they would fold in on themselves and direct a high energy beam of sunlight towards the target and vaporize them and so the ships would communicate with patches that were basically QR codes on the outside of their hull and the other ship would take pictures and be able to transfer data that way.

I want to say they were using the equivalent of high refresh rate E-Ink screens.