Fascinating technology

This amazing technology can recover pixelated words from redacted documents

If you used pixelation to redact sensitive information, you might want to use a different method instead, because a security researcher has developed a new way to successfully recover pixelated words from redacted documents.

Senior researcher from security firm Bishop Fox, Dan Petro has published a new blog post detailing how he was able to completely recover text from an image that was redacted using the rasterization method.

While media and researchers often use pixelation or blurring to hide text in sensitive images posted online, Petro has demonstrated that it’s much safer to use opaque bars to hide text instead.

Petro began his research on how to recover pixelated words from redacted documents after Jumpsec Labs issued an open challenge to anyone to decipher the text in a pixelated image. After researching a number of pixelation and de-obfuscation techniques, he found a solution to the challenge and sent his findings to Jumpsec Labs.

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Although there are a number of existing photo editing tools to enhance pixelated images of people or landscapes, until now there was no tool capable of recovering text found in pixelated images. .

For this reason, Petro and Bishop Fox released a new open source tool on GitHub called Unredacter. The tool is able to correctly reconstruct the original text of a document in its entirety if it has been redacted using rasterization.

Petro provided additional information on how users who need to write text in a document should do so in his blog post, saying:

“The bottom line is that when you have to write text, use black bars that cover all of the text. Never use anything else. No pixelation, no blurring, no blurring, no swirling. Oh, and make sure you change the text as an image Don’t make the mistake of changing your Word document to have a black background with black text.

Fortunately, many of the best PDF editors such as Adobe Acrobat DC already offer the ability to redact text in sensitive business documents.

Via BleepingComputer