ISP heavyweights join forces to fight child porn

Five of the largest American ISPs are partnering up to fight child pornography. AOL, Earthlink, Microsoft, United Online (Netzero/Juno) and Yahoo will help the National Center for Missing and Exploited Children (NCMEC) by developing a database of child-pornography pictures and donating $1 million dollars. The database will contain mathematical signatures, known as "hash" values, for known child-porn images.

The NCMEC will actually collect the images and then create the signatures. Each ISP would then use the joint database to scan images sent by their own users. Matches will be sent to the NCMEC for further investigation.

Computer forensic investigators, like those using Guidance Software’s Encase, have used hash databases for years to search for child pornography images. As hard drives balloon in capacity, hash value comparison is becoming a necessity. A hash signature is made by filtering the image down to an almost unique 128 to 512 bit number. Those values are then compared to a database of images from previously convicted child offenders.

ISPs already routinely scan member emails for spam and viruses. In addition, most of this scanning already uses hash signature matching, so it would be trivial to add the proposed picture matching process.

In related news, the House Subcommittee on Oversight and Investigations has just started a two day hearing about the Role of ISP’s and Social Networking Sites. Officials are concerned that ISPs and social networking websites don’t retain evidence neede to convict sex offenders.

Congressman Bart Stupak (D-MI) told the panel that 80% of the pornographic images of children on the net involve children ages 12 and under ; 40% involve kids ages six and under ; 20% involve toddlers 3 years of age and under.