The Solution to the 10th Anniversary Code

A few weeks ago, [1o57], a.k.a. [Ryan Clarke] gave a talk about puzzles, DEFCON, and turning crypto puzzles into an art form at our 10th anniversary party. Ever the trickster, [1o57] included a crypto challenge in his talk, and a few days after our little shindig, nobody had yet solved the puzzle. Finally, someone bothered to sit down and figure it out. We don’t know what [tahnok] won, but as [1o57] said, solving it is its own reward.

Some of the slides in the presentation had a few characters sitting off to the side for no apparent reason. [tahnok] put these together and came up with:

DOXIYLDCYVDKIKNKUMKRYDNBYGONYMNXOC

In cases like this, you might try a Caesar cipher, or just shifting characters to the left or right a certain number of places. Since [1o57] noted this was the tenth anniversary of Hackaday, [tahnok] tried that first:

TENYOBTSOLTAYADAKCAHOTDROWEDOCDNES

It doesn’t look like much, but that’s only because the string is backwards. Tricky, tricky. tricky. With instructions to send a codeword to an email address, [tahnok] now needed to find a code word. There was one picture [1o57] put up on twitter that was still an unsolved part of the puzzle:

men

With no idea what these little stickmen are, he scoured google with variants of ‘stickmen code’ and ‘semaphore’ until he hit upon the Sherlock Holmes story, The Adventure of the Dancing Men. It’s a simple substitution cypher, translated to, “codeword psychobilly ciphers”

And that’s the entire puzzle. As far as we know, this took about a month to solve, and compared to the DEFCON challenges, was fairly simple. [1o57] will probably chime in down in the comments to tell everyone how many people have picked up on the clues and sent an email.

GSM Cracked

[Karsten Nohl], with a group of security researchers has broken the A5/1 Stream Cipher behind GSM. Their project web site discusses their work and provides slides(pdf) presented at 26C3. A5/1 has had known vulnerabilities for some time now and is scheduled to be phased out for the newer KASUMI or A5/3 block cipher. This should be an interesting time in the cell phone business.

Thanks to [Tyco] and [MashupMark] for pointing us to this story.