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Re: Google's email scanning

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Rich wrote:
> Mike Easter wrote:
>> Hils wrote:

>>> ca database of ?hashes? ? unique codes that
>>> correspond to known images of abuse and that allow the company to
>>> ?look? for abusive content without examining the image itself or
>>> keeping a permanent database of abusive content.

So the term 'unique' is not appropriate in this instance.

>> So, the child porn fiends who acquire or distribute such images
>> should make some small change in the image so that the hash is
>> different; if I'm understanding this policing mechanism.
>
> It is unlikely they are using cryptographic hashes, for just this very
> reason.  They are probably using something similar to phash
> (http://www.phash.org/) where small changes to the image produce close
> enough hashes to tag "similar" to them.

I don't really understand yet what/how phashing - perceptual hashing - 
works in the way I understand crypto hashing.  Wikipedia doesn't have an 
article.  It has one on digital video fingerprinting, which must be 
based on similar principles and algos.

It would seem to me that if a coder had a good understanding of how 
phashing or digital video (or audio) fingerprinting works, they/one 
could develop a strategy for making the least modifications 
algorithmically which would most adversely affect/neutralize the 
fingerprinting algos.



-- 
Mike Easter

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Thread

Google's email scanning Hils <hils@saynotospam.net> - 2014-08-05 05:44 +0100
  Re: Google's email scanning Mike Easter <MikeE@ster.invalid> - 2014-08-05 14:43 -0700
    Re: Google's email scanning Rich <rich@example.invalid> - 2014-08-06 01:34 +0000
      Re: Google's email scanning Mike Easter <MikeE@ster.invalid> - 2014-08-07 10:20 -0700
        Re: Google's email scanning Rich <rich@example.invalid> - 2014-08-08 23:12 +0000
          Re: Google's email scanning Mike Easter <MikeE@ster.invalid> - 2014-08-08 22:19 -0700
  Re: Google's email scanning john <nospam@no.net> - 2014-08-19 12:57 -0800
    Re: Google's email scanning Huge <Huge@nowhere.much.invalid> - 2014-08-20 08:45 +0000

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