01 January, 2007

National Treasure

Happy New Year!

Anyone remember National Treasure from 2004? The film itself, something of a Da Vinci Code style adventure starring Nicolas Cage, wasn't that great. However, it had some fun DVD extras. One was a short featurette on codes and ciphers, and in the background were various things flying about, including a few rather obscure historical cipher machines; none of these machines were mentioned in the featurette itself.

Your challenge, if you choose to accept it, is to identify the three cipher machines and the cipher machine component depicted in the following screen captures (click to enlarge).

29 December, 2006

Stuart Milner-Barry

Cipher Text is back! Apologies for the lack of activity here for most of 2006, hopefully I'll be posting more frequently in 2007. Anyway...

Last week I revamped the Wikipedia entry for Sir Stuart Milner-Barry, chess player, civil servant, and the head of Hut 6 at Bletchley Park from October 1943. He is particularly remembered for co-authoring a letter directly to Winston Churchill requesting more resources for the codebreakers, bypassing the apparently ineffectual leadership at Bletchley Park. The letter, which was also signed by Alan Turing, Gordon Welchman and Hugh Alexander, outlined their needs for a relatively small number of additional clerical staff in order to carry out their work effectively. Milner-Barry delivered the letter in person to 10 Downing Street in October 1941. After reading it, Churchill, who was a keen consumer of Bletchley Park's product, memo'd his staff with the terse but unambiguous "Make sure they have all they want on extreme priority and report to me that this had been done." With "ACTION THIS DAY" stamped above it in big letters. It seemed to have the desired effect.

18 February, 2006

Herivel Tip

Bletchley Park has announced a forthcoming lecture by WWII veteran codebreaker John Herivel, a Hut 6 mathematician who, within weeks of arriving at BP, had come up with a nifty bit of lateral thinking to help solve Enigma. Dubbed the Herivel tip or Herivelismus, it relied on Enigma operators taking a shortcut and not randomising the rotors after having set up the machine. If you're interested, I wrote up the details in a Wikipedia article. It was Hut 6's lifeline for a few months in the Summer of 1940 after the Germans had changed their indicating procedure, obsoleting the Polish techniques then in use.

Herivel's tip reminded me of combination locks, of the type with rows of dials of digits. On university campus, I've noticed that many people in a hurry don't really scramble their combination locks (for cycles, normally) very thoroughly -- maybe a quick flick of the dials with the thumb, or something of that sort. As a result, the state after a half-hearted scramble still reveals information about the secret combination. I did some tests (on a lock of my own, of course), and if you observe several of these states, and you have a reasonably accurate model of what weak scrambling method is being used, you can whittle down the possibilities pretty quickly. Still, a good old-fashioned pair of bolt cutters is less hassle...

06 January, 2006

Marian Rejewski on Wikipedia

The Wikipedia article on Polish mathematician Marian Rejewski is currently going through the process to become a so-called "Featured Article", vetted entries that are eventually promoted on the main page and elsewhere.

Feel free to read the article and add any comments. The page for the Featuring process can be found here.

Despite having something of a girl's name, Rejewski was a veritable geek hero, solving the wiring of the German Enigma machine using some funky maths. It's more than possible that, without Rejewski's results, the British at Bletchley Park would have had little, if any, success with Enigma.

Rejewski also had a more exciting wartime experience than his counterparts at Bletchley Park, who were all off playing rounders in relative safety. From September 1940, Rejewski worked with a small unit on breaking Nazi ciphers from within occupied (well, Vichy) France, under the continual threat of discovery and arrest. After being nearly discovered by a detector van equipped with a radio antenna, the unit was evacuated. Aided by the French resistance, Rejewski worked his way to the border and attempted to cross over into Spain. He didn't have much luck at this point: robbed by his guide at gunpoint, captured by Spanish police only hours after crossing the border, and then interred for three months in prison.

After his release, he made his way to Britain. You might assume he would join the codebreakers at Bletchley Park on Enigma, since their work had built on his. Instead, he was assigned to a unit working on low-level codes; a decision that one former British codebreaker described as "like using racehorses to pull wagons". It's difficult to tell what motivated this apparent injustice -- perhaps a need for security, particularly since the British had developed more advanced techniques than those of Rejewski, and the future of Poland itself was uncertain. It's also possible that the relevant authorities did not know of the Polish contribution to the British work. Most of the few that had known were no longer immediately involved with Bletchley Park.

Regardless, Rejewski deserves to be remembered as one of the "greats" in crypto history.

05 January, 2006

National Cryptologic Museum

Adjacent to the NSA headquarters in Maryland, USA is the National Cryptologic Museum, a museum of cryptology and NSA history open to the public. It's surely second only to Bletchley Park as the ultimate day out for crypto geeks (if geeks had days out, that is).

Regrettably, I've not had chance to visit -- it's a bit of a trek from the UK -- but the next best thing is a superb set of photos posted to Flickr by Austin Mills which document a large proportion of the museum's exhibits. The photos are high enough resolution to be able to read the captions and see the details of the various machines.

01 January, 2006

From the archives: Mercury

I had chance to spend a day at the UK National Archives a couple of weeks ago, and came across a file (AVIA 65/977) discussing cash awards to the designers of Mercury, an on-line cipher machine used by the RAF from 1950 to the 1960s. I wrote up all the information I could glean about this machine in a Wikipedia article.

Mercury embodies a similar principle to the US SIGABA (ECM Mk II) machine: some rotors control the movement of other rotors. It would appear that Mercury was an independent reinvention of the concept, as the ECM was around a decade older. The ECM concept had been kept secret from the UK by the US, and a Combined Cipher Machine (CCM) was used instead for inter-allied communication.

Another feature of Mercury appears to be that of "double rotors". Exactly how this worked wasn't clear from the PRO documents, but one plausible guess is that there were two independent wirings inside each rotor core, and that these wirings could be set in 26 offsets from each other, and optionally reversed. The current would pass once through the "inner" wiring, and then back again through the "outer" wiring. Ordinary Typex rotors had a "double" contact feature used to improve the reliability of the electrical contacts; this could have been pressed into service as a double rotor feature. Each pair of double rotors would, of course, step together.

14 November, 2005

British rotor machine: Singlet (BID/60)

It's fun to see more information on rotor machines entering the public domain. For example, the Swiss NEMA machine was declassified in 1992. More recently, lots of information on the Soviet rotor machine Fialka (M-125) has been published on the Internet. There's even been a loosening of information about the US/NATO KL-7 system.

This year, a British rotor machine named Singlet (BID/60) was put on display at Bletchley Park in the superb Enigma and Friends exhibit put together by David White and John Alexander. There doesn't seem to have been much -- if anything -- written about this machine in the open literature.

The caption at Bletchley Park reads: "Singlet was used mainly by the British intelligence services C. 1949 / 50 onwards. This is a `Cold War' machine using wired rotors to achieve secure messages. We are very grateful to the Foreign and Commonwealth Office and GCHQ for this opportunity to show `Singlet' here at BP."

Singlet has windows and stepping levers for ten rotors. The rotor tube appears to be a detachable section, labelled BID/60/3, while the base unit is labelled BID/60/1. There is a hint of a connection to the KL-7 in this naming. According to George Mace on Jerry Proc's KL-7 page, the KL-7 components were originally labelled as follows: "the base unit was AFSAM 7/1 (aka KLB), rotor stepping unit AFSAM 7/2 (aka
KLA) and rotor basket AFSAM 7/3 (aka KLK)." The rotor tube, stepping levers and the keyboard are also all somewhat suggestive of some sort of link or common ancestry with the KL-7.

Some photos can be found on Wikipedia/Commons: 1, 2, 3, 4 and 5.