[tptacek]

They can't use the same technique, or any technique with similar privacy tradeoffs, to look for tax fraud.

The scheme they use here only works with documents known to authorities, whose possession is criminalized. The technique (searches for collisions in a corpus of robust hashes) can't generate new information for authorities about documents they haven't seen. And there is no case in which a person could possess those documents where the government wouldn't have a reasonable interest in knowing that; in other words, there's no valid privacy interest intrinsic in possessing one of the specific documents they're looking for.

None of those conditions exists for tax fraud, or for that matter terrorism.

The slippery slope you're invoking doesn't really exist.

[potatosareok]

Searching for collisions in a corpus of robust hashes seems to me like the post office drug sniffing packages, and people seem to be ok with that. The same way the drug sniff dog won't give away anything other then drug/no drugs (is that how they work? I thought so?), this scheme shouldn't give anything away more then CP/no CP.

At the same time I think that to eliminate CP entirely you need to get rid of some of the freedoms we enjoy. I'm sure you can 100% get rid of CP if you track what everyone is looking at on their computers, but is that a tradeoff you want to make? Even if the filter really only can ever report looking at CP/not looking at CP, would you be comfortable with that running on everything you own?

I could be arguing to a nonsensical extreme, but the NSA tracking all data is following this to some perverted extreme - if we can track EVERYTHING that is going on, and eventually actually make actionable data out of it, we can catch all the criminals/stop crime. But I think we accept the possibility of a bit more crime in exchange for preserving some of our freedoms.

[TheOtherHobbes]

>They can't use the same technique

It's not the technique, it's the precedent. The technology is really not the point here.

>None of those conditions exists for tax fraud, or for that matter terrorism.

Actually they exist for both. Google is only one possible access point for monitoring.

The question is whether we want Internet services of all kinds of to be part of a culture of automated state surveillance.

I'd suggest there are good reasons for answering that question with a firm 'No'.

[tptacek]

I don't think it's about the technique. The "precedent" (set at least 3 years ago, when this was all announced publicly) involves the tradeoffs.

The technique comes into the picture because there is no technique for detecting tax fraud that makes the same tradeoffs.

I don't have any trouble believing simultaneously that we shouldn't have a "culture of automated state surveillance" and that it's OK to sweep image uploads for matches against known child pornography. Just like I had no problem with metal detectors, but do have a big problem with millimeter wave imaging.