An interesting-sounding document referred to by Alfred Martin in 1906 (pp.174-175, thanks to Stefan Mathys!) is Cod. Sang. 760, the contents of which the St Gallen archivists describe as follows:

This manuscript, illustrated with numerous colored pen drawings, originated in a secular environment in Southern Germany or in Switzerland around the middle of the 15th century. It describes the signs of the zodiac, the planets, the four temperaments, and the four seasons regarding their influence on human health. This is followed by dietary guidelines primarily regarding bloodletting, but also regarding eating, drinking, sleeping, waking, resting and moving, as well as, in concrete terms, regarding bathing (illustration p. 101) or defecating (illustration p. 120)

As to the manuscript’s origins, the archivists suggest:

Most likely an amateur doctor with an interest in astronomy, from the Southern region of Germany, wrote the original text around 1400 and assembled it into a compendium. Later the text was repeatedly supplemented and modified.

There are numerous reasons why I’m intrigued by Cod. Sang. 760: not only its zodiac roundels, but also the sun-moon roundels on adjacent pages, and the textual focus on all the things I’ve recently been wondering whether the Voynich zodiac pages encode – blood-letting, baths, clysters (enemas), etc.

“Iatromathematisches Hausbuch” manuscripts

Yet Cod. Sang. 760 (which was only digitized in 2014) is but one of a series of “Iatromathematisches Hausbuch” manuscripts, some of which were discussed on Stephen Bax’s site back in 2015, e.g.:

* Cod. Pal. Germ. 291

* Cod. Pal. Germ. 557

…and so forth. The 30-element list of Saint’s Days that appear on twelve pages at the start of these also appear in other manuscripts, perhaps most notably this one from Konstanz in 1463 (as mentioned by Rene):

* Planeten-Buch – BSB Cgm 7269, Konstanz, Anfang 15. Jh. bis 17. Jh. [BSB-Hss Cgm 7269]

What is interesting in CGM 7269 is that not only does the Sagittarius crossbowman appear, but also the image of two people in a bath (previously used to illustrate bathing) has been appropriated for the Gemini zodiac sign.

(There’s also Tübingen Md 2, MS Cod Sang 827, and Strasbourg Ms.2.120 to consider, etc.)

I could go on, but I hope the basic point – that we are looking at a family of manuscripts with many similar features – is clear.

The copied crossbowman hypothesis

I’m acutely aware that what follows is less of an outright answer than a provocation towards approaching an answer.

The first step is hypothesizing the origins of the Sagittarius crossbowman: I now feel quite sure that it was a copying error within the basic Iatromathematisches Hausbuch manuscript family, where a crossbowman roundel originally drawn to accompany the constellation Sagittarius was miscopied into the zodiac roundel accompanying the zodiac sign Sagittarius.

This is hardly a huge departure from what has been noted before, specifically when Rafal Prinke and Rene Zandbergen asked Prof. Ewa Sniezynska-Stolot of the Jagiellonian University in Cracow and Prof. Dieter Blume (respectively) about this.

However, by positing the crossbowman drawing as a copying error, we can start to view the Voynich Manuscript’s zodiac section not just as something visually influenced by a set of manuscripts, but as a member of the cladistic tree of a specific family of manuscripts.

The iatromathematical table/label hypothesis

Structurally, these iatromathematical housebooks have quite stylized layouts and contents. For example, they typically start with a nineteen-column computus table (which was no secret at all), followed by a set of twelve tables of Saint’s Days (I believe), with 30 elements in each list.

In the Planeten-Buch, these lists have further become associated with zodiac signs, in much the same way that we see in the Voynich Manuscript (albeit in a non-obvious way).

It would therefore seem reasonable to secondly hypothesize that the contents of these tables might have (in some way) ended up as the Voynich zodiac labels (e.g. using some combination of abbreviation and acrostic), i.e. from tables to labels.

Incidentally, this would be the kind of “block paradigm” match I’ve talked about for some time here. The reason I think it is of particular cryptographic interest is that there is good cryptanalytical reason to suspect that the Voynich’s “labelese” (i.e. the version of the text used to write labels) is only a subset of the ‘language(s)’ used to write the main text. As such, labelese may well be weaker and hence easier to break.

Where next?

So far, I have only looked at a handful of manuscripts, and from these have elicited only the outline of a research angle.

But the real historical heavy lifting – building a complete list of these fifteenth century manuscripts, and then deriving a cladistic tree linking them all together – must have been done already, surely?

Can I therefore again ask my German-speaking readers for their help, this time to dig up any literature looking at this family of manuscripts as a whole?

I’m sure it’s out there, but I haven’t yet found it. All pointers, tips and suggestions gratefully received! 🙂

The Voynich Manuscript’s zodiac roundel section has long frustrated researchers’ efforts to make sense of it at a high level, never mind determining what any specific zodiac nymph’s label means.

However, I can now see the outline of a new hypothesis that might explain what we’re seeing here…

A Stylistic Impasse?

The fact that each zodiac sign has thirty nymphs, thirty stars and thirty labels (all bar one?) would seem to be a good indication that some kind of per-degree astrology is going on here: and this is a lead I have pursued for many years.

The literature on this, from Pietro d’Abano to Andalo di Negro to (the as yet unseen) Volasfera, is uniformly Italian: so it would seem a relatively safe bet that the source of this section is also from that same Italian document tree.

At the same time, the observation that the drawings in the zodiac roundels are stylistically quite distinct from the rest of the Voynich Manuscript’s drawings has been made many times.

Combine this with the fourteenth century technological dating for the (unusual) Sagittarius crossbow, and you get loosely driven towards a working hypothesis that at least the central figures were copied from a (still unknown) late 14th century or early 15th century woodcut almanach, of the type that was most commonly found in Germany and Switzerland.

However, this leads to an awkward stylistic impasse: how can this zodiac section be both Italian and German at the same time?

Klebs and Martin

Back in 2009, I mentioned Arnold Klebs’ very interesting 1916 article on the history of balneology in the context of discussing Quire 13. However, there was another intriguing quote there that I only got round to chasing up a few days ago:

The yearly pilgrimages to the healing springs in the month of May, the baths of the women on St. John’s Day, which Petrarca describes so picturesquely in one of his letters from Cologne, were ancient survivals, indications of a deeply rooted love for and belief in the purifying powers of the liquid element. These seasonal wanderings to the healing springs were naturally brought into relation with astral conjunctions, a tendency soon exploited by the calendar makers and astrological physicians. Days and hours were set for bathing, blood-letting, cupping, and purging, carefully ascertained by the position of the stars. Martin in his book gives a great variety of such instances which offer interest from many points of view.

The author and book to whom Klebs is referring here is Alfred Martin and his immense (1906) “Deutsches Badewesen in vergangenen Tagen“, Jena : Diederichs. (The link is to .)

It turns out that Klebs sourced a great deal of his article from Martin’s labour of love (with its 159 illustrations and its 700-entry bibliography), which covers public baths, private baths, Jewish baths, bath-related legislation, mineral baths, bath architecture, bath technology, spas, saunas, and so forth, ranging from Roman times all the way up to 1900, and with a dominant focus on German and Swiss archival sources.

The Zodiac Bath Hypothesis

You can by now surely see where I’m heading with this: a zodiac bath hypothesis, where the Voynich’s zodiac section was in some way a copy of a German/Swiss original, which itself brought together the two traditions of per-degree astrology and good/bad times for “bathing, blood-letting, cupping, and purging” (as described by Klebs).

In some ways, this should be no surprise to anyone, given that the first few nymphs are all sitting in barrels, which were essentially what medieval private baths were (well, half-barrels, anyway).

And perhaps, in the context of clysters (enemas), it’s not inviting too much trouble to speculate what legs drawn apart / together might be representing. 🙂

The problem is that – probably because of my only fragmentary German – I can’t find any mention of “Days and hours were set for bathing, blood-letting, cupping, and purging, carefully ascertained by the position of the stars” in Martin’s German text.

I can see plenty of references to blood-letting (“aderlass”) etc, but pinning down the exact part that Klebs robbed out has proved to be beyond me.

Can I therefore please ask a favour of (one or more of) my German readers; which is simply to find the section in Alfred Martin’s book to which Krebs was referring? Thanks! 🙂

It would seem likely that this will then refer to a book in Martin’s capacious bibliography, at which point the game is (hopefully) afoot!

Having now reread Ian Pfennigwerth’s “Man of Intelligence” and gone through various files at the NAA, I now have slightly more solid dates framing what Captain Nave was doing in 1949.

Nave’s Career

Having started work in the South Australian Railways (where his father Thomas worked), Eric Nave signed up for the Royal Australian Navy in 1917. He stayed there until 1930, when he was moved to the Royal Navy.

However, Nave’s RN personnel file is not only fairly brief (he was cheerful and intelligent), but only runs to 1948.

A large proportion of the papers in his NAA ASIO file relate to his pension, because his Royal Navy pension was not transferable to his wife. Because the Naves had four children, this issue required a fair bit of administrative attention. Redactions are merely senior officers’ names.

I incidentally found out that Nave owned a Holden sedan, and that his parents lived at 5b Arlington Terrace, Allenby Gardens, Adelaide.

Captain Nave’s 1949 Timeline

From the papers in the files, we can say definitively that Captain Nave: [page numbers from the ASIO file NAA: A6119, 3576]

* finished formal work with the RN in March 1949 (p.80)

* was allocated to the Terror “18.3.49 for dispersal” (Navy service record)

* had 160 days of untaken / carried over holiday (Pfennigwerth), though the Navy service record says “48 days N.S.L.  28 days E.O.W.L.  56 days release + RAN F.S.L.”

* was courted by ASIO as early as 13th May 1949 (p.87)

* officially retired on 22nd August 1949   (when his pension started) (pp.30-31)

* started with ASIO on 20th October 1949  (pp.30-31)

All of which means that Adelaide-born-and-bred Captain Nave was still (technically) in the Royal Navy in July 1949, when the Adelaide newspapers reported that a “local Navy decoder” was having a look at the Rubaiyat.

Are any of his children still alive?

The notion that Jorge Luis Borges’ “Labyrinths” – a collection of idiosyncratic short stories, essays, and even parables by the much-acclaimed Argentinian writer, wrangled into English with no little hair-pulling – somehow parallels Voynich research is one that has been floated and repeated for decades.

But is it true now, here in the Fake News world of 2017? Is Borges a harbinger of what we see, or are we all post-Borges?

Describing The Indescribable

What Borges does in his short stories is to gleefully plunder history, not for mere colour (as so many writers now do) but to subvert it and channel it into a secret paradoxical alt.history, which typically forms the conceptual spine of each story’s skeleton.

The twisted steps backwards he takes to go forward again are equal parts erudite and imaginary. These all lead to a creative pyre whose flames are fed by philosophy, religion, esotericism, literature, self-referentiality, dreams, chess, labyrinths, and the numberless ways to cheat (or at least sidestep) the infinities of time, space, and mathematics.

Yet despite the range of references, the setting is predominantly a high-register, sexless, atheistic domain, ruled by stern, darkly logical planets. As a reader, you often feel as though the author is trying to conjure up a paradoxical exit visa from one dark oppressive reality into another.

Borges’ Three Tells

It’s not hard to tell his writing apart from just about anybody else’s.

His first writing trademark is embellished and over-decorated footnotes and references to books and articles which may or may not exist, embedding (if not actually entangling) his narratives in an imaginary textual web. This corresponds to the “falsifying and magnifying” tendency he derides himself (at a remove) for.

His second trademark is inserting himself into his stories, often as an unreliable narrator (not such a modern conceit as some may think).

His third trademark is that his stories almost always reveal themselves to be less than the sum of their parts – the denouement is often little more than a peek behind Oz’s curtain, collapsing the conceit preceding it.

Is Borges Worth Reading?

This is a tough question. Many of the things that are good about his writing would also likely make him completely unreadable to many modern readers. If you are impatient and/or prefer things to be grounded in the concrete, Borges’ concept-heavy counter-factuals are almost certainly not for you.

Yet the bigger problem, I think, is one of style, because Borges writes with a kind of refined, over-polished lightness that somehow never quite becomes levity. I don’t believe that the reading difficulties are translation artefacts: they’d be just as difficult in Hawaiian or Esperanto.

Is Borges a fellow-traveller to Voynich researchers? He certainly sets his readers cerebral challenges, ones which wear cloaks of obscurity, esotericism, and a tight knowingness, yet which he then reveals to be simpler than they at first seemed: and in some ways this is the (idealized) research trajectory.

But in the end, I think the answer is no: his mystification and erudition aren’t his means to knowledge, they are merely the scaffolding he uses to support the canvas behind his all-too-briefly-erected stages. Borges offers only an anagram of research, not research itself: the teasing paranoia of conspiracy, rather than causality.

Don’t get me wrong, I like Borges: but, like fried grasshoppers dipped in Marmite, I can quite see he’s not going to be to everyone’s tastes. :-/

In July 1949, Australia’s greatest code-breaker Captain Eric Nave was enjoying his 160 days of accumulated holidays before starting a new job with (the newly formed) ASIO on 15th December 1949. I suspect he was at his house in Adelaide Melbourne at the time, but asked over by his father in Adelaide, where he had lived until early on in the war.

Hence I strongly believe that the “local naval decoder” referred to in reference #4 below was Eric Nave. I would be delighted if anybody has suggestions as to how this could be tested or pursued further in the archives.

(1) The Adelaide Advertiser, 26th July 1949, p.3

Yesterday the police interviewed two suburban telephone subscribers whose numbers corresponded with those on the back of the book, but they knew nothing of the matter.

(2) Adelaide News, 26th July 1949, p.1

Phone number found on cover of book

[…]The woman whose telephone number appears in pencil on the cover of the book told police that when she was nursing at North Shore hospital in Sydney about three and a half years ago, she gave a similar copy to a lieutenant who served in the Water Transport section of the Army.

Later, she said, the lieutenant wrote to her mother’s home in Melbourne. She replied to his letter, telling him she was married.
Subsequently, the woman told police, she and her husband settled in Adelaide. Last year a man called at the house of a neighbor, inquiring for a nurse he once knew.

This afternoon the woman is being shown the plaster cast of the Somerton victim, which is now in a storeroom at Adelaide Museum.

Acting on the possibility that the “Rubalyat” in their possession did belong to the lieutenant, police set out to decipher a number of block letters pencilled on the back of the book.

Although the lettering was faint, police managed to read it by using ultra-violet light. In the belief that the lettering might be a code, a copy has been sent to decoding experts at Army Headquarters, Melbourne.

(3a) The Adelaide Advertiser, 27th July 1949, p.1

Army Officer Sought To Help Solve Somerton Body Case

[…]The police have also forwarded to Army Headquarters, Melbourne, a copy of a series of letters printed in pencil on the back of the book. They believe that it is possible that the letters may be some coded message. Police located the woman from a telephone number, also written in pencil on the back the book.[…]

(3b) Adelaide News, 27th July 1949, p.1

Yesterday police traced a telephone number pencilled on the cover to the Adelaide woman who gave a similar copy of the book to the Army lieutenant.

Efforts to decipher several rows of block letters, believed to be a code, on the back of the book are continuing. A Navy “code cracker”, is tackling the task this afternoon.

(4) Adelaide News, 25th August 1949, p.22


Police were told today that Australia’s top cipher experts had failed to crack the code in the back of a copy of Omar Khayyam’s “Rubaiyat’ believed to be connected with the Somerton body mystery.

A naval spokesman said experts in Melbourne had worked on the code for weeks. Melbourne authorities had informed him that the frequency of the occurrence of letters, while inconclusive, corresponded more favorably with the table of frequencies of initial letters of words in English than with any other table.

A reasonable explanation would be that the lines were initial letters of words of a verse of poetry or something like that.

Before a copy of the code was sent to Melbourne, a local naval decoder expressed similar views.

The code, printed in pencil in the back of a copy of the “Rubaiyat” from which the words “Tamam Shud” – meaning “The End” – were torn, was thrown into the back of an unattended car at Glenelg about the time the body of an unknown man was found on Somerton beach on December 1, 1948. In the clothing on the body was a neatly trimmed piece of paper with the words “Tamam Shud.”

(5) Adelaide News, 27th August 1949, p.2

Many try to solve Somerton code

[…]Expert opinion is that the code was made up of initial
letters of words from a verse of poetry or something similar.

The code is:
M R G O A D A B D [sic]

Vic. man’s claim

Melbourne. – A former newspaper seller, Mr. Ernest Jessup, of Caulfield, thinks he may have solved part of the code.
This is how he worked it out:
MRGOADABD [sic] – Mr. Goddard
MTBIMPANETP – Pantryman(?).
MLIABOAIAQC – Mail-boat-AQC (AQC, A class quarters?)
Mr. Jessup believes this hides the name of a ship – his guess is an Indian ship.

Here’s something a little unusual for you all – a feature-length 1971 episode of a Sci-Fi series called “Name of the Game” on YouTube, and set in “A.D. 2017” (also the name of the episode):

Interestingly, the director was a young Stephen Spielberg (it was one of his earliest pieces of work); while its author was American writer Philip Wylie, whose career moved from screenplays to slushy novels to non-fiction to dystopian fiction (and then dotted around between them for several decades).

But more about Wylie (and his connection to a cipher mystery) in a separate post. For now, on with the show! Enjoy! 🙂


You might instead ask: “Was the author of the Voynich Manuscript a nymphomaniac lesbian from Baden Baden obsessed with clysters?”

Or how about: “Was the author of the Voynich Manuscript a medieval psychoactive drugs harvester from (the place now known as) Milton Keynes?”

Or: “Was the author of the Voynich Manuscript a Somalian Humiliatus obsessed with mis-shapen vegetables starting with the letter ‘A’, writing down the results of a six-year-long trek through the Amazon rainforest in a perversely private language?”

The answers to these are, errrm, no, no, and no (respectively).

When the Voynich Manuscript contains so many unexplained points of data (a thousand? Ten thousand?), why on earth should I or anyone else spend more than a minimal amount of time evaluating a Voynich theory that seems to attempt to join together just two of them with what can only be described as the flimsiest of thread?

What – a – waste – of – time – that – would – be.

I’ve just uploaded a draft paper to called Fifteenth Century Cryptography Revisited. This takes a fresh look at the topic (specifically at homophonic ciphers, Simonetta, and Alberti), and takes a view quite different from David Kahn’s (now 50-year-old) interpretation.

Please take a look: I don’t yet know where it will end up (i.e. as a book chapter, a journal article, or whatever), but I thought it would be good to push the current version up, see what people think.

The abstract runs as follows:

Fifteenth Century Cryptography Revisited

In the fifteenth century, the art of secret writing was dramatically transformed. The simple ciphers typical of the preceding century were rapidly replaced by complicated cipher systems built from nulls, nomenclators, homophones and many other tricks.

Homophones – where individual plaintext letters were enciphered by one of a set of different shapes – were, according to David Kahn’s influential interpretation, added specifically to defend against frequency analysis attacks. Kahn interprets this as a sign of the emergence of cryptanalysis, possibly from Arab sources, and also of the growing mathematization and professionalism of cryptology.

However, by closely examining key ciphers and cipher-related texts of this period, this paper instead argues that homophones were instead added as a steganographic defence. That is, the intention was specifically to disguise linguistic weaknesses in Italian and Latin plaintexts that rendered ciphertexts vulnerable to easy decryption.

Building on this analysis, a new account of the history of fifteenth century cryptography is proposed, along with a revised model charting the flow of ideas influencing cryptographic practice during this fascinating period.

Though it runs to eighteen pages, it should be easy to pick up and read. Please let me know if there’s anything that you think needs clarification, or which you think is incorrect etc.

Between 22nd March 2005 and 6th August 2006, someone calling himself/herself “IKLP” (supposedly an acronym for “I Killed Laci Peterson”) posted a large number of comments to the (now-defunct) Internet forum. These comments were mocking, often rhymed (badly), and referred more than a few times to the Zodiac Killer, e.g.

Green River was a bore. Zodiac but a little whore. I am the one to adore. I be the one you should never ignore.

*sigh* So far so nothing. Yet two of these comments appeared to contain codes:

* The IKLP Short Code (10th September 2005)


* The IKLP Long Code (30th October 2005)

Fore if you break the code. Then it is you who will know.


Fore now we will see. If you are as smart as me.

Farmer’s “solution”

In 2008, Christopher Farmer (he of the now-defunct OPORD Analytical forum) posted up what he claimed were the solutions to both of these. In short, Farmer concluded that the IKLP Long Code referred to the solar clock in Cesar Chavez Park (specifically the word “DETERMINATION”), while the IKLP Short Code referred to a specific address:

City Finance and Customer Service
1010 Tenth Street, Third Floor, Suite 2100
Modesto, California, 95354

Unfortunately, Farmer’s Byzantine proofs and long-winded arguments were, as solutions go, no less voluminous than vacuous: for precision, they were right up there with picking random words from the OED or sticking pins into a Borgesian map. Truly, truly horrible.

But the right question to be asking is something far simpler: are these even real codes?

Code or fauxed?

The long string of (basically) wacko-style comments surrounding the codes would give many onlookers good reason to think they came from a person who was somewhat unhinged. But to walk away purely for that reason would be intellectually chicken: we should have the confidence in our cryptanalysis and observation skills to have a look regardless, right? So let’s try…

The short code doesn’t seem to offer much to bite on: it’s just too short. However, I did wonder whether the long code might be (if you remove all the non-digits) a two-digit homophonic cipher:

23 34 34 22 34 54 56 82 40 06 19 05 43 34 06 34 54 33 44 45 99 43

99 83 45 11 94 34 59 95 39 86 55 56 66 94 95 94 54 22 07 86 2

99 32 33 34 88 42 86 59 99 66 69 22 16 64 94 54 95 00 96

34 59 99 64 38 52 34 39 94 50 99 23 49 93 88 49 39 00 45 29 45 42 37 09 00 34 00 93 45 11 95 44 52 19 83 59 95 21 99 54 45 94 39 90 94

99 54 32 95 99 65 99 92 34 49 39 93 39 67 23 95 99 33 49 60 41 68

23 75 93 96 34 67 81 60 72 34 56 43 45 20 05

This has a fairly strong distribution, with 34 and 99 coming in at 9.1% and 7.6% of the total letters respectively (remember that E = ~12.49% and T = ~9.28% in English):

[13] – 34
[11] – 99
[ 7] – 45, 94, 95
[ 6] – 39, 54
[ 4] – 00, 23, 49, 59, 93
[ 3] – 22, 33, 43, 56, 86
[ 2] – 05, 06, 11, 19, 32, 42, 44, 52, 60, 64, 66, 67, 83, 88, 96
[ 1] – 07, 09, 16, 20, 21, 29, 37, 38, 40, 41, 50, 55, 65, 68, 69, 72, 75, 81, 82, 90, 92

All of which might (weakly) argue not for an out-and-out homophonic cipher, but rather for a nomenclatura-type cipher, where some number pairs stand in for common words or (more rarely) syllables; or alternatively a simple cipher that was augmented by adding a load of nulls.

And yet at the same time, it feels to me as though this has only managed to cut close to the core of what’s going on here, but not right to its middle. But even so, it might (possibly) be a start.

What do you think?

I posted up seven homophonic challenge ciphers a few days ago, and now – though it may sound a little counter-intuitive – I’d like to try to help you solve them (bear in mind I don’t know if they can be solved, but the whole point of the challenge is to find out).

Of the seven ciphers, #1 is the longest (and hence probably the easiest). Reformatted for ten columns rather than five (it uses five cycling alphabets ABCDE, ie. “ABCDE ABCDE” over ten columns):

121,213,310,406,516, 108,200,323,416,513,
112,208,308,409,515, 102,216,309,425,509,
114,215,309,417,507, 102,201,323,401,517,
111,200,306,408,500, 113,203,313,407,512,
103,223,313,403,511, 119,213,316,416,511,
102,204,324,418,517, 120,203,324,407,516,
105,209,312,401,504, 117,208,310,408,500,
113,203,301,425,513, 115,201,313,408,515,
115,214,308,406,501, 122,204,322,408,509,
114,209,305,412,504, 117,213,316,402,509,
100,200,310,423,513, 100,214,320,419,509,
114,209,309,419,520, 101,200,320,416,518,
120,211,313,403,509, 103,207,313,421,513,
107,209,305,407,523, 115,224,313,416,508,
102,203,306,416,514, 107,200,310,401,509,

Repeated Quadgram

Commenter Jarlve (whose interesting work on the Zodiac Killer ciphers some here may already know) noted that there is a repeated quadgram here, i.e. the sequence 408 500 113 203 appears twice.

This is entirely true, and also a very sensible starting point: I’ve highlighted this quadgram in the following diagram, along with all other repeated A-alphabet tokens (i.e. 100..125), and also any tokens they touch more than once (i.e. in the B and E alphabets):

Another thing that’s interesting here is that the 102 token (that appears four times and is coloured purple in the above) appears with four different letters before it as well as four different letters after it. In classical cryptology, that’s normally taken as a strong indicator that this is a vowel: and with the high instance count (4 out of 31, i.e. 12.9%), you might reasonably predict that this is E, A, O, or perhaps I (in order of decreasing likelihood).

[Note that I haven’t looked to check what letter this actually is: having created the challenge ciphers, I’ve just left them to one side, and don’t intend to look again at them.]

Similarly, the 114 token (that appears three times and is coloured green) is always preceded by 509, and is followed by 209 on two of the three instances. (Note that the token two after it is 309 in two of the three instances as well.) Again, in classical cryptology, these kind of structured contacts are normally taken as strong indicators that this token enciphers a consonant: and with the high instance count (3 out of 31, i.e. 9.7%), you might reasonably predict that this enciphers T or possibly N, S, or H.

With these two examples in mind, it strikes me that for any given plaintext language (English in the case of these challenge ciphers) you could easily build up probability tables for repetitions of the two tokens before and the two tokens after any given token: and then use those as a basis to predict (for a given ciphertext length) which plaintext letter they imply the letter is likely to be.

Though this may not sound like very much, because you can do this for all five of the alphabets independently, the results kind of rake across the ciphertext, yielding a grid of probabilistic clues that some clever person might well use as a basis for working towards the plaintext in ways that wouldn’t possible with randomly-chosen homophonic ciphers. Just sayin’. 😉

And The Point Is…

It’s entirely true that for homophonic ciphers where each individual cipher is chosen at random, the difficulty of solving a reasonably short cipher with five homophones per letter would be very high. But knowing (as here) that each column is strictly limited to a given sub-alphabet, my point is that many of the tips and tricks of classical cryptology are also available to us, albeit in slightly different forms from normal.

Yet while it’s encouraging for solvers that there is a repeated quadgram here, I don’t currently believe that cipher #1 will be (quite) solvable with pencil and paper, as if it were a Sudoku extra-extra-hard puzzle (though as always, I’d be more than delighted to be proved wrong).

However, my hunch remains that strictly cycling homophonic ciphers may well prove to be surprisingly solvable using deviousness and computer assistance, and I look forward very much to seeing how they fare. 🙂