Change one bit, now we have a brand new hash
Comment on Take It Down Act Has Best Of Intentions, Worst Of Mechanisms
t3rmit3@beehaw.org 1 day ago
I’m extremely wary of any law that can be used to censor or otherwise remove material online, but one gripe i have with the Techdirt article is their assertion that hash matching is expensive or difficult.
Generating a SHA hash of an image when uploaded is very inexpensive in terms of processing, and there’s already going to be a db somewhere that stores the image metadata, so it’s not like putting the hash there is hard. Similarly, a simple No/SQL lookup for a known hash is incredibly simple and non-intensive.
The real issue is the lack of an appeal mechanism, the lack of penalty for our legal mechanism to ignore false reports (which should probably about spam/ volume rather than single requests), and the lack of definition around what exactly a site must do to show good-faith, reasonable compliance.
ryannathans@aussie.zone 1 day ago
jarfil@beehaw.org 1 day ago
Depends on “how identical” is “identical”.
The SHA hash of a file, is easy to calculate, but pretty much useless at detecting similar images; change a single bit, and the SHA hash changes.
In order to detect similar content, you need perceptual hashes, which are no longer that easy to calculate.
t3rmit3@beehaw.org 23 hours ago
jarfil@beehaw.org 22 hours ago
The problem lies in what is a “depiction”. The way it is written, even cropped, rotated, blurred, or in any other way processed files of that “depiction”, would fall under the “identical” part.
Since perceptual hashing does exist, there are open source libraries to run it, and even Beehaw runs an AI based image filter, the “reasonable effort” is arguably to use all those tools as the bare minimum. Even if they sometimes (or always) fail at removing all instances of a depiction.
But ultimately, deciding whether a service has applied all “reasonable efforts” to remove “identical copies” of a “depiction”, will fall on the shoulders of a judge… and even starting to go there, can bankrupt most sites.
chicken@lemmy.dbzer0.com 1 day ago
Why “no longer”?
vrighter@discuss.tchncs.de 1 day ago
because of the “perceptual” part.
A normal hash has the property that it produces wildly different hashes for even the tiniest of changes in the file.
Perceptual hashing flips that requirement on its head, and therefore makes finding a suitable hash function much harder.
chicken@lemmy.dbzer0.com 1 day ago
Oh, the way I read it it seemed like they were saying perceptual hashes used to be easier to calculate