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Best to redact using black rectangles. However, when you redact a PDF, make sure you don't just draw rectangles over the text, the text remains and can be easil
by AlexDragusin 2y ago
Best to redact using black rectangles. However, when you redact a PDF, make sure you don't just draw rectangles over the text, the text remains and can be easily extracted. Add the rectangle as is but then export to raster images like PNG/JPG then recombine these in a PDF.
If your redacted documents are to be printed, ensure that you first redact then print. If you must print then redact (let's say you prefer to redact a physical document), photocopy the redacted document and distribute that, so the text cannot be forensically recovered.
Anything else (blurs etc) are prone to reversal or leakage.
- foobarian 2y ago> photocopy the redacted document tbh I would be wary of this too; if you use a run-of-the mill office copy station that defaults to color copies you never know what information might leak in the subtle gray scales.
- atommclain 2y agoI have a vague memory of someone being able to fairly accurately estimate redacted words and phrases in a government document by using the size of the blacked out portion along with the font metrics. I think the safest way to redact text would be to first normalize it all to the same text (maybe something like "etaoin shrdlu" from the hot type era), then black it all out, then there would be even less information leaked.
- purple-dragon 2y agoYou are correct. Font character-width analysis + NLP = Exposure
- maicro 2y agoGot it, use fixed-width fonts for everything.
- purple-dragon 2y agoThat would make it even easier to determine the length of the redacted word.
- ryandrake 2y agoThis is especially true when the list of potential words is known. So if you know the court case is about Mark, Sandeep, and Elizabeth, and the names are redacted with boxes, then it's trivial to unredact each name by just looking at the length of the boxes.
- hayleox 2y agoIf you have the paid version of Acrobat, the built-in redact tool is pretty nice. It lets you just highlight the text you want gone, but it will properly remove that text and the image.
- Someone 2y ago> photocopy the redacted document and distribute that, so the text cannot be forensically recovered. To be really safe, you will want to check whether the photocopier forgets about your document after copying. Many photocopiers store documents on hard disks before copying them, and there’s no guarantee that the data is deleted afterwards. https://www.cbsnews.com/news/digital-photocopiers-loaded-with-secrets/ https://www.cbsnews.com/news/digital-photocopiers-loaded-wit...: “In 2008, Sharp commissioned a survey on copier security that found 60 percent of Americans "don't know" that copiers store images on a hard drive. Sharp tried to warn consumers about the simple act of copying. "It's falling on deaf ears," McLaughlin said. "Or people don't feel it's important, or 'we'll take care of it later.'" All the major manufacturers told us they offer security or encryption packages on their products. One product from Sharp automatically erases an image from the hard drive. It costs $500. But evidence keeps piling up in warehouses that many businesses are unwilling to pay for such protection, and that the average American is completely unaware of the dangers posed by digital copiers.” (I think selling users that as an add-on is almost criminal. Copiers should make sure documents don’t survive on disk after copying (not even as bits in a now deleted, but not overwritten, file), unless explicitly instructed by the user to do so)
- Clamchop 2y agoSelling something so simple for an incredible markup to ameliorate a problem of your own creation is just good business.