“That tells us about how the text was laid out,” Levchenko says. The software is constructed by inferring how the original document was produced-for instance, in Microsoft Word-and then reverse engineering the specifics of the document. The tool is essentially able to automatically compare the size of the redaction and the position of the letters with a predefined “dictionary” of words to estimate what has been replaced. “It’s pretty clear to a lot of people that the letter ‘L’ is skinnier than a letter ‘M,’ and that if you redacted just the letter ‘L,’ then you might be able to tell it is different from a redaction with just the letter ‘M,’” Bland says. Plus, a new attack method they devised makes it possible to extract secret details from the redacted text.Įdact-Ray focuses on the size of glyphs (broadly, characters or letters) and their positioning. The findings, from researchers Maxwell Bland, Anushya Iyer, and Kirill Levchenko, say two of the most popular tools for redacting documents offer no protection to the underlying text at all, with the text accessible by copying and pasting it. New research from a team at the University of Illinois looked at the most popular tools for redacting PDF documents and found many of them wanting. When this redaction is done incorrectly, people’s safety and national security can be put at risk. The majority of redactions-by government officials and courts-involve placing black boxes over text in PDFs. Now that most documents are digitized, securely redacting their contents has become harder. If this didn’t work, a chunky black marker pen would do the job. For years, if you wanted to protect sensitive text in a document, you could grab a pair of scissors or a scalpel and cut out the information.
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