[gruez]

>The main thing I would worry about is actually not Apple; instead (1) what information might Apple hide in plaintext in the image that a third party could extract?; and (2) what identifiers might there be that a third party could use to correlate multiple images as from gorgoiler?

A lot, actually. But why Apple would take the engineering resources to implement this, and risk all the reputation damage? If they're doing it for the money, how would they monetize it? If they're being coerced by the government, what's the government's motivations? In both cases, is smuggling bits in screenshots really the most plausible way to do it? Surely there must be some better way stenography in screenshots?

>But honestly it just feels odd to upload a screenshot without doing something to scrub it. I find it helpful to practice good security even when, as you point out, the probability of it being necessary is very low.

On the flip side, if you do unusual obfuscation of your uploaded image (eg. heavy post processing), that in itself is an identifying characteristic. You're going to be that guy who uploads his screenshots in greyscale, with heavy compression and blurring. https://xkcd.com/1105/