The Internet is a strange thing, a virtual photographer’s jacket crammed with countless pockets of enthusiasts. For example, you beautiful cipher mysteries fans circulate within one bijou (but nicely-appointed) pocket, while the massed legions of Slashdot fans have a Tardis-style hyperzoom lens pocket all of their own. But… what would happen if these two worlds collided?

A chance to find out came in December 2009, when Edith Sherwood’s The-Voynich-Manuscript-was-made-by-Leonardo-da-Vinci-so-it-was website got picked up by Slashdot. From the 4900 overspill visits Cipher Mysteries got at the time, I estimated that she must have had “(say) 30000 or more” visits. This was probably about right, because in the few days since the same thing happened to Cipher Mysteries last weekend, its visit counter has lurched up by 38,000+. The onslaught started on Saturday night, when at its peak the Cipher Mysteries server was getting a new visitor roughly every second. By late Sunday, however, the story had finally slid off the bottom of the Slashdot front page (which only ever lists the ten most recent news items), at which point the tsunami turned into merely a large river. 🙂

According to the server logs, my Slashdotted Chaocipher page was read in 132 countries (USA 52%, Canada 8%, UK 7.5%, Australia 5.4%, etc), while US Slashdotters were mainly from California, Texas, New York, Washington, followed by another long tail. And OK, I know it’s a biased sample, but it was nice to see Internet Explorer in less than 8% of the browsers. One long-standing stereotype did fall by the wayside, though: there was a relative absence of trolls leaving snarky comments. Might Slashdot be *gasp* growing up? 😉

Actually, the nicest thing about the whole episode for me was that Moshe Rubin’s brother in Florida was unbelievably impressed when he saw Moshe’s name pop up on Slashdot. I know it’s only a small thing, but I’m really pleased for the guy, he deserves credit for his hard work and persistence bringing the Chaocipher out into the light.

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Some quick follow-up thoughts on the Chaocipher…

It strikes me that Byrne’s neologism “Chaocipher” was remarkably prescient for 1918, because the whole idea of “chaos theory” – as per Wikipedia, “the behavior of dynamical systems that are highly sensitive to initial conditions“, AKA ‘the butterfly effect’ – had not long before that been started by Henri Poincaré. The French mathematician had shown that the classical three-body problem sometimes yielded tricksy outcomes that never converged (i.e. to a collision) nor diverged (i.e. to increasing distance from each other), but where the three bodies were somehow trapped in a dynamically constrained yet utterly mad-looking (OK, he actually said ‘nonperiodic’) manner. Yet after this promising beginning in the 1880s, the ‘chaos’ concept’s journey onwards was a particularly arduous (and non-obvious) one: even though people noticed the signatures of this odd behaviour in many different contexts, they had no comfortable vocabulary to describe it until well after Benoit Mandelbrot and Edward Lorenz in the 1960s.

And so I find it neatly uncanny that the Chaocipher appropriates the “chaos” word 50 years earlier than it should, while at the same time exactly demonstrating the properties that contemporary mathematicians now ascribe to it (i.e. “deterministic chaos”). As the cipher’s twizzling steps subtly mangle the order of the letters on the two rotors, both the error propagation and the cipher system complexity sharply ramp up over time, in a (quite literally) chaotic way: to my eyes, Byrne’s Chaocipher is no less artful and pleasing than any Mandelbrot set I’ve ever seen. However, because its mechanism was not disclosed until this year (2010), it is perhaps best thought of part of the secret history of applied chaos: by way of comparison, the earliest paper on “chaotic cryptography” I’ve found was Baptista’s “Cryptography with chaos” in Physics Letters A (1998) [mentioned online here].

So, it might be that as the full story behind the Chaocipher emerges from Byrne’s papers, we’ll discover that he cleverly applied Poincaré’s and Hadamard’s ideas to cryptography: but – between you and me –  I somehow doubt that this is what really happened. In my mind, there’s something both ham-fistedly mathematical and deviously mechanical about the Chaocipher, that makes its mongrelly combination of Alberti’s cipher wheel and movable circular type something that could (in principle, at least) have been devised any time since about 1465. All the same, I think that the single aspect of the Chaocipher that most makes it resemble an out-of-place artifact is that it is a pure algorithm made solid – a bit like a programming hack devised by someone who had never seen a computer. Perhaps programming is closer to carpentry than we think!

Without doubt, the Chaocipher lies just outside the rigid mathematical confines of the cipher development path laid down by the sequence of crytographers since Alberti: and so for me, the most inspiring lesson to be learned from it is that genius need take only a single step sideways to become utterly unrecognizable to the mainstream. Thinking again about the Voynich Manuscript’s cipher, might that too merely stand a single conceptual step beyond our tightly-blinkered mental range? Furthermore, might that also ultimately turn out to be part of the same secret history of applied chaos? It’s certainly an interesting thought…

The Chaocipher” is a devious cipher system invented in 1918 by John F. Byrne: allegedly, it was so complex that nobody could crack his challenge ciphertexts (even with the plaintext to refer to!), yet was so simple that its mechanism was claimed to comprise only two rotating disks small enough to fit in a cigar box, and could be operated by a ten-year-old (admittedly a diligent, determined and well-practised one) to encipher and decipher texts.

Hence, the Chaocipher’s long-standing mystery revolved around three questions:

  1. Was the Chaocipher for real? (i.e. could something so simple really produce such tricksy ciphertext)?
  2. Was it more secure than, say, the Enigma machine?
  3. More to the point, is the Chaocipher actually an unbreakable cipher?

As of a few years ago, only three people knew the Chaocipher’s secrets – John Byrne Jr (the inventor’s son), and two Cryptologia editors (who saw it in 1990 but were sworn to silence). Yet as Chaucer noted, time and tide wait for no man (not even Cryptologia editors) – so there was a very real (and growing) possibility that the secrets of the Chaocipher might somehow get lost forever.

Hence last August, Moshe Rubin – who CM readers may well recall as the zesty Israeli software / crypto guy who not long before had set up the Chaocipher Clearing House website – decided to try to contact John Jr before it was too late, and so cold-called his way through the list of Byrnes living in Vermont. Before long, Moshe found himself in contact with Patricia Byrne (John Jr’s wife) from whom he discovered the sad news that her husband had passed away a year or two previously.

However, because Pat Byrne was already looking for a buyer for her husband’s cryptological material, Moshe put her in contact (via David Kahn) with David D’Auria, the chairman of the National Cryptological Museum’s Acquisitions Commitee. Somewhat surprisingly, after a couple of months Pat Byrne very generously decided to donate the whole set to the NCM, a terrific gesture which I (for one) highly appreciate (and I hope that you do too!)

And so it came to be that Moshe Rubin found himself allowed what he describes as “preview access to some of the material“.  Although he found that the precise setup John Byrne Sr had employed was not immediately obvious from the material to hand, Moshe burnt a load of midnight oil (is elbow grease more or less inflammable?) before finally managing to reconstruct the original algorithm in all its subtly obfuscatory glory.

Just as Byrne had described, his Chaocipher used two rotors (with the plaintext alphabet on the right rotor and the ciphertext alphabet on the left rotor) BUT with both alphabets altered slightly (let’s call this process ‘twizzling’, for want of a better word) after processing each letter. I’ve hacked together a 30-second Chaocipher animation on YouTube to try to demonstrate Byrne’s twizzlification…

Rather than go through the fine details here, I’m happy to refer you to Moshe’s detailed (and very readable) description of the process here: the only significant difference between my video and his text is that because the rotors mesh (and hence physically rotate in opposite directions to each other), the numbering sequence on each rotor is reversed relative to the other – i.e. even though #1 is at the top of each rotor, #2 and #3 proceed clockwise on the right (plaintext) rotor but anticlockwise on the left (ciphertext) rotor. Whereas in his text, both numbering systems run in parallel to each other (which might confuse you, it certainly confused me a little).

Of course, the obvious practical weakness of the Chaocipher is that any errors in enciphering, transmission, and deciphering get near-irreversibly propagated through the rest of the message: which probably makes the whole system too fragile to use in wartime, however cryptographically secure it may be (and, answering the second question above, I suspect that it may well prove to be more complex than Enigma, for it really is quite a fiendish system).

But is it (practically) unbreakable? Well, the obvious answer would be that if it has now been released into the wild, you’d have thought someone in a three-letter-agency (or GCHQ, naturally) would have worked out a clever way in. However, I’m not 100% sure that has happened yet… so, interesting times.

All credit to Moshe Rubin, then, for his persistence and hard work bringing this cipher mystery into the light: he has a Cryptologia paper coming up, and plenty more work to do over coming months (or years?) fleshing out the behind-the-scenes story from the stack of Byrne’s papers now in the NCM. It’s a fascinating slice of cipher history, and I wish him the very best of luck with the inevitable book and selling the movie rights! 😉

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Update: I’ve added a follow-on Chaocipher post here, discussing the intriguing parallels between the Chaocipher and chaos theory…

A highly surprising message just arrived here at Cipher Mysteries from our Chaocipher Clearing House chum Moshe Rubin:-

Is your readership aware that NSA has placed the entire text [of Mary D’Imperio’s “An Elegant Enigma”] on its site?

I couldn’t find the link on your site so here it is!

This is a great find, highly recommended for all Voynich researchers – if you haven’t read it already, download it straight away! Having said that, even though it took me six attempts to download it completely (doubtless they were tracert’ing me to see if I just happened to be a terrorist, bless ’em), I did get it all in the end. But please let me know if this happens to get removed (which is always possible).

Incidentally, this is just one of a number of cryptological history publications the NSA has kindly made available on its website. The 2007 article by John Clabby on Brigadier John Tiltman (“A Giant Among Cryptanalysts“) is also well worth looking at (though not nearly so essential as D’Imperio, naturally).