The FBI and the US Department of Justice have announced that, as far as they were concerned, notice and take down now had almost zero value as an aid to law enforcement re child porn. The highly organised, technically literate distributors have by
and large deserted publicly accessible places, burrowing deep into file sharing environments, peer-to-peer networks and closed groups of one kind or another. Police work today in this field is principally covert, intelligence led. Obviously the US
Government was not saying they were indifferent to the images remaining on public view. Getting them off any and all parts of the internet remains an important goal of policy for everyone, particularly the child protection community. The Feds were simply
pointing out that the amount of time and money devoted to notice and take down was disproportionate to the benefits obtained in terms of reducing the total volume of illegal activity or helping to secure convictions. Step forward Microsoft. They
have described new software they had developed. It's called PhotoDNA. Microsoft will give it away free to appropriate companies. Every image stored on a computer can already be reduced to a nearly unique hash value . There are various
programmes around that can pick up and read these values and compare them with known illegal images. The trouble is if anyone does anything as elementary or obvious as edit the picture, even by the tiniest fraction it then takes on a totally different
hash value. The picture then goes undetected. By contrast PhotoDNA looks at what makes the picture what it is i.e. the visual content. Thus, even if the picture changes format, shape, size or colour, within certain generous tolerances it will
still be picked up. Using the parameters Microsoft recommends the chances of the software making a mistake seemingly are around 1 in 10 billion. It may be several years before we see how well PhotoDNA works at scale around the world. Using a
database of illegal images supplied by the National Center for Missing and Exploited Children Facebook is currently trialling it in an environment in which between 200 and 300 million new pictures go up every day. The early signs are good. PhotoDNA in the wrong hands might be a worry. It could be used to prevent publication of a cartoon of the King or the Archbishop. Microsoft is fully aware of this and will be watching like hawks how their licences are deployed.
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