In a spectacular snafu, the Transportation Security Administration stupidly posted an entire airport screening procedures manual on a government website. The 93-page document included details on special screening rules for diplomats, CIA and law enforcement officers; a list of items for which screening is not required (like wheelchairs, casts, orthopedic shoes); and the fun fact that during peak travel times, TSA screeners who check IDs only use black lights to authenticate 25% of documents. Some of these secrets were revealed because, apparently, somebody erroneously believed they were redacted. But The Wandering Aramean blog, which discovered the oopsy, explains why that didn’t work:
They apparently don’t understand how redaction works in the electronic document world. See, rather than actually removing the offending text from the document they just drew a black box on top of it. Turns out that PDF documents don’t really care about the black box like that and the actual content of the document is still in the file.