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We always did need those algorithms. There was a paper a few years ago on decoding gaussian-blurred documents to reveal the redacted passages. The only safe way
by hopeless 15y ago
We always did need those algorithms. There was a paper a few years ago on decoding gaussian-blurred documents to reveal the redacted passages. The only safe way is to completely remove the original pixels, e.g. by drawing a black box over the text.
- shabble 15y agoand not by just drawing that box over them in the original (textual content) pdf. You need to squash it down to images, then destroy the bits you need to. (There might be other ways, but enough Big Government Agencies have screwed it up to make it worth noting) Is the 'decoding' paper this one: http://dheera.net/projects/blur.php http://dheera.net/projects/blur.php ? The blur function is just smearing pixel values across their neighbours in blocks, so you can treat it as a hashing function, and then generate enough candidates that eventually you get something that hashes correct (or close enough) I'm not sure how practical it'd be on data longer than a credit-card number, but it's an interesting hack nevertheless.