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Interpol APB proves police agencies can now unscramble digitally blurred images

Sleepwalk | 13.10.2007 07:34 | Repression | Social Struggles | Technology | World

Digitally blurred images from protests or other actions which can incriminate people involved are not safe to post publicly. Police now can unscramble the encryption behind this security device.

A press release from the international police agency appealing for the public to aid in the capture of a notorious child molester who has posted videos of himself on the Internet raping dozens of young boys, included four images of the man's face reconstructed by specialists in the German national police agency. An agent involved in the decision to release the images publicly said he was opposed to the move since it would let 'criminals' know the police can now unscramble digitally blurred images, but after years of fruitless searching for the child molester, Interpol decided to ask the public for help.

The consequences for people involved in all manner of illegal political activity could not be clearer- DO NOT rely on technology to protect you online or in using telecommunications. It's simply too risky that the police can in future access communications which today they cannot. After all, they target people and keep records of electronic communications for good reasons. Not to make people paranoid, but this is a wakeup call for anyone involved in risky activity. Don't get caught doing something stupid.

From the Guardian article:

"Techniques are always developing," he said. "What is impossible today is possible tomorrow. There were several attempts to clear the face ... We are sure that you can't get better pictures and the people in his neighbourhood - family friends, colleagues, whatever - they will recognise him."

Mr Persson added that he had opposed making the photos public because it demonstrated to criminals that police could now unblur pictures, but that consideration and the risk the man could face public humiliation or violence were outweighed by the desire to protect children.

"It was a long discussion," he said. "We can't just sit here and do nothing. We have exhausted all possibilities within police work to find this man ... This was the last step."

Sleepwalk
- Homepage: http://www.guardian.co.uk/international/story/0,,2186568,00.html

Comments

Hide the following 6 comments

Sloppy Work

13.10.2007 08:07

The "encryption" of the original photo appears to have been performed with somewhat linear algorithm, whereby an equation describing a spiral of a fixed ratio, with the origin centered on the iris of one eye, was applied to the digitized photo. It wouldn't take much to "reverse engineer" that algorithm from the "encrypted" product, and "break the code." The "encrypted" image in the comment above just isn't chaotic, and might more correctly described as "scrambled".

Even if the spiral encryption algorithm used in the example had been applied several times, using a different axis on each pass, superimposed on the previous encryption product, the final product would still have betrayed its method, and the multiple spiral scramblings could have been unpeeled back to the original source photo.

A more robust encryption process would involve a more thorough, pseudo-random scrambling of the bits/pixels of the original photo by some equation that isn't so graphically apparent in the final product. More security could be obtained by successive encryptions (encrypting the encryption) using a variety of equations applied variously to parts of previous successive encryption products.

In other words, state security forces can't be said to have closed the book on image encryption as suggested in the orginal article posted above.

The purpose in the example wasn't (apparently) to protect information from detection from unauthorized eyes, ensuring revelation of the original to only authorized recipients. (In that case, the more complicated the encryption process, the more burdensome and corruptible it would be to decrypt.) Since the apparent purpose in the example was to obscure identity from all eyes, forever, a very complex, convoluted encryption process would carry no security/complexity trade-offs.

(It almost appears that the alleged perp, in his alleged photo, was engaging in the detective story cliché proverb: that self-absorbed clever outlaws--heros and villains, alike--like to brag. It seems that he wanted to "be cute", show how "clever" he [thinks he] is, daring someone to catch him. If he really wanted to remain anonymous, he would have done a more thorough job of concealing facial identity.)

I agree that the less reliance on the false "holy grail" of technology, the better. Primitive, one-time pad encryption beats the most tech-intense encryption every time.

alt0156


by the way...

13.10.2007 08:12

i haven't posted this info anywhere else, and it doesn't seem to be too widely published. please take a minute or two to let people know, post to lists, etc. the more people know the better decisions we can all make in dealing with this sensitive issue.

Sleepwalk


addition to sloppy work

13.10.2007 10:41

The description above is a good comment and explanation. There was also an actually interesting thread in a similar vein on Slashdot when this was reported:  http://yro.slashdot.org/article.pl?sid=07/10/09/0235235

geek


The Photo

13.10.2007 10:42

Photographer


try and uncrypt

13.10.2007 14:37

a mask

hmm


What about putting a black circle over the face?

10.05.2009 04:01

What about totally covering the faces in a photograph, such as with dark shapes?

Also, word to the wise, a good tip if you're putting out photos where you've obscured the faces is to do a screen capture of the image and then distribute that screen capture image of the photo rather than the original file, this helps to eliminate possible identifying traces that would be in the original image file.

hm


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