Blurring Images Not So Secure 166
An anonymous reader writes "Dheera Venkatraman explains in a webpage how an attacker might be able to extract personal information such as check or credit card numbers, from images blurred with a mosaic effect, potentially exposing the data behind hundreds of images of blurred checks found online, and provides a ficticious example.
While much needs to be developed to apply such an algorithm to real photographic images, he offers a simple, yet obvious solution: cover up the sensitive information, don't blur it."
Re:Impossible! (Score:5, Informative)
Re:Japanese porn (Score:5, Informative)
Now cue about 50 posts talkng about the "CSI Photoshop enhance plugin".
RTFA (Score:5, Informative)
The whole point of the article is that blurring and pixelating beyond recognition isn't enough. You don't need to see the original numbers, you just have to find numbers that blur to a similar blob. It's a dictionary attack with blur as a hash function.
MaxEnt (Score:5, Informative)
maximum entropy (Score:5, Informative)
In the real world, data is imperfect and noisy, so the article is thus far correct. What is not correct is simply to pick the data with the nearest match, because it's a best match to the noise also. Maximum entropy is one algorithm which gives you a probabilistic answer, i.e. "the chances that this particular combination is the right one is [whatever] percent". You then pick the most likely one. Astronomers use this technique all the time for removing the blur and diffraction on their images. I personally use it regularly for nuclear spectroscopy, and it's absolutely solid if you use it carefully.
Fragment-based image completion/reconstruction (Score:2, Informative)
There's quite a few more impressive papers on his page, for those interested in graphics.
Re:Japanese porn (Score:2, Informative)