(Source: Interpol)
Interpol released these images to enlist public assistance in tracking down this unidentified man. (Source: Interpol)
Authorities post his face publicly and receive a torrent of replies
A man suspected of sexually abusing children was publicly
unmasked last Monday when Interpol successfully unscrambled images of his face.
Crops of the scrambled and unscrambled images were posted to Interpol’s
website, along with a public plea for help, as all police efforts at
identifying him thus far have failed.
Working from the original images found on the internet,
specialists from the Bundeskriminalamt, or
Germany’s Federal Criminal Police Office were able to successfully reverse what
appears to be Photoshop’s twirl distortion tool, using unspecified methods. “Techniques
are always developing. What is impossible today is possible tomorrow,” said
Anders Persson, the Swedish police officer in charge of overseeing Interpol’s
child abuse image database.
The images, which were taken in Cambodia and Vietnam
sometime during 2002 and 2003, have been making the rounds around the internet
underground in a series of about 200 images depicting the abuse of 12 young
boys, whose ages range from six to the early teens.
Persson was initially hesitant to release the photos
publicly, as it would signal to criminals that police forces were capable of
unblurring images. Outweighing that consideration, however, was his interest in
protecting other children from predators. “It was a long discussion,” said
Persson, “… we have exhausted all possibilities within [the] police to find
this man … this was the last step.”
For decades the scrambling of images – usually with a mosaic
or blur filter – has been common practice in protecting private information and
safeguarding the identities of publicly pictured individuals. In an article
titled “Why Blurring Sensitive
Information is a Bad Idea,” Dheera Venkatraman outlines the method for a
possible attack against scrambled images using a technique similar to rainbow table attacks
that are used against one-way
scrambled hashes frequently used for storing passwords. His conclusion: “don’t
blur your images!”
Interpol received over 200 messages in
the first 12 hours after releasing images of the man’s face. “We have a lot
of responses and they are coming from all over the world,” said Persson, with
some messages including detailed information that includes names and addresses.
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