that's what i figured. i guess what i wondered is if users are able to revoke their willingness to (potentially) store something unsavory post facto and/or if the content link was shared to block prescriptively.

if i only wanted dog pictures on my computer and blocked any cat picture content i came across (for example), could that block all future attempts to store a portion of any content i chose to block, as long as the key/hash matched?

hypothetically, that aproach could narrow it down to where if virtually all people chose to block a file, it might stop circulating and only exist on a single person's hard drive. i realize, though, that it wouldn't take much to alter a file slightly and alter its hash therein