Steganography And The War On Child Porn

A few weeks ago I wrote about steganography — the hiding of information inside other stuff, usually referring these days to hiding data inside photographs (FEER column here, WSJ.com here; both subscription only).

One usage I missed was in trying to track down paedophiles. So instead of bad guys hiding their bad stuff inside other files, police appear to be able to use a similar technology to trace the bad guys. Australia’s Sunday Telegraph (subscription only) reports on how the country’s high-tech police squad is “using evolving new technology to catch criminals, such as special ‘signatures’ on digital photographs that can tell investigators where and when an image was taken.” Already, the paper says, “one of these signatures has helped police to find one abused young Australian girl whose photographs had been posted on the Internet.”

The paper doesn’t go into further detail, but I assume the use of steganography in this case would involve embedding something into a digital photograph which might then be able to ‘phone home’ in some way. Or does anyone have any better ideas?

The Australian High Tech Crime Centre (AHTCC) campaign is part of Operation Auxin, which has already “resulted in the arrest of more than 200 people”, the paper says.