A stick figure guide to the Advanced Encryption Standard. [via Bruce Schneier]
posted by Electric Dragon on Sep 26, 2009 - 21 comments

XKCD author Randall Munroe appears to have left a neat little cryptographic puzzle for Reddit users in his new book. They're trying to decipher it.
posted by zarq on Sep 21, 2009 - 44 comments

Thomas Jefferson's cipher message from Robert Patterson For more than 200 years, buried deep within Thomas Jefferson's correspondence and papers, there lay a mysterious cipher -- a coded message that appears to have remained unsolved. Until now.... To Mr. Patterson's view, a perfect code had four properties: It should be adaptable to all languages; it should be simple to learn and memorize; it should be easy to write and to read; and most important of all, "it should be absolutely inscrutable to all unacquainted with the particular key or secret for decyphering." [more inside]
posted by caddis on Jul 2, 2009 - 22 comments

Christopher Farmer of Opord Analytical has just posted his solution (PDF) to part 4 of the much studied "Kryptos" cipher. He's recently cracked Zodiac Killer ciphers thought unsolvable for nearly 40 years and has a theory (PDF) about the Zodiac Killer's possible identity that is hard to be ignored. Mr. Farmer freely shares his many discoveries on his website's forum board.
posted by wherever, whatever on Nov 23, 2008 - 58 comments

In March 2007, the FermiLab Office of Public Affairs in Batavia, IL "received a curious message in code" via USPS. In May 2008, scientists posted a facsimile image of the letter to their blog in the hopes of soliciting cryptologists to decipher the letter. [more inside]
posted by subbes on Jul 16, 2008 - 45 comments

The Codex Seraphinianus, that rare and amazing volume, has been scanned in high-res glory and posted to Flickr. If you are lucky enough to afford it, copies are available. Previously.
posted by suckerpunch on Mar 20, 2007 - 59 comments

If you work at Langley and you need a break from actual intelligence gathering, you can always try to crack the code to the sculpture right outside the cafeteria window. Kryptos is a sculpture by James Sanborn located on the CIA grounds which contains a four-part coded message: sections 1-3 have been solved (with Sanborn admitting he made a typo in section 2). Perhaps you'd like to join Elonka (and the hive mind) in having a go at section 4.
posted by goodnewsfortheinsane on Dec 3, 2006 - 14 comments

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posted by Plutor on Jul 5, 2005 - 69 comments

The most mysterious manuscript in the world. The Voynich Manuscript is 235 page manuscript written in a cipher that has yet to be decoded. The manuscript includes many images. Almost all pages of the manuscript are available online. There have also been several books (1,2)written claiming to solve the manuscript. You can also follow the modern day progress of deciphering the Voynich manuscript.
posted by patrickje on Jan 15, 2003 - 35 comments