Was Exhibit 5 of the Chaocipher ever solved, and if so who solved it and when?

Question

Was Exhibit 5 of the Chaocipher (published c.1991) ever solved, and if so, who solved it and when?

Chaocipher is a cipher that was created by J.F. Byrne in 1918 as a machine-based cryptography system, and in 1953, used it to create a code challenge in his autobiography "Silent Years".

He included four encrypted texts (the four exhibits) in Chapter 21 of his book, and included the encrypted text and plaintext for all for exhibits, except for the 4th one, where he did not include plaintext and omitted the last two lines.

It is known that at the time, there were at least 3 people other than him that knew how the cipher worked: his son, and the two editors of the journal Cryptologia who were let in on the secret in 1990, and that he tried unsuccessfully to get the Army and Navy interested in the encryption method, even though the encryption device could supposedly fit in a matchbox.

The cipher remained publicly unsolved until May 2010, when Byrne's materials were donated by his estate to the National Cryptologic Museum, and the encryption method was first publicly described by Moshe Rubin in July of that year. At the time of it being publicly described, Exhibits 2, 3 and 5 have still not been deciphered.

While I have found a solution for Exhibits 1, 2, 3 and 4 (heck, I've even solved Exhibit 1 myself!), I have not been able to find a solution for Exhibit 5, published later in 1991.

I have found links on the internet where people have claimed to have solved Exhibit 5, however I am not able to find a resource on the internet that does not lock me behind a paywall before I am able to access the solution and how it was solved.

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Further reading

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Chaocipher, Wikipedia

Moshe Rubin, Chaocipher Revealed: The Algorithm

Answer 1

Yes

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The solution was published online in January 2014 in Chaocipher Exhibit 5: History, Analysis, and Solution of Cryptologia's 1990 Challenge by Jeff Calof, Jeff Hill and Moshe Rubin.

With the hint that "The plaintext, which is typical English prose, is taken from Stewart C. Easton's book, Rudolf Steiner: Herald of a New Epoch", and a document donated by Byrne's family showing the schema and solution, the solution was published as follows:

Keys:

Cipher Key: IMAGINATIONINSPIRATIONINTUITION
Takeoff Pattern for Key: RLRRLLLRRRLLLLRRRRRLLLLLLRRRRRR
Takeoff Pattern of Message: RLRLRLLLRLRRRRLRLRLRLLLRLRRRRLRLLRLRLLLRLRLRRRLRLRLRRRRRLRLRLRL

Plaintext:

Message 1:

EVERYTHING THAT HAS EVER HAPPENED ON EARTH STEINER TELLS US AND EVEN EVENTS THAT HAVE TAKEN PLACE IN THE SPIRITUAL WORLDS ARE INDELIBLY RECORDED

Message 2:

OUR OWN MEMORIES ARE MYSTERIOUS ENOUGH EVEN TO OURSELVES AND WE SHOULD RECOGNIZE THAT THEY DO NOT EXIST IN SPACE ONLY IN TIME AND THAT THEY ARE IN ALL RESPECTS IMMATERIAL

Message 3:

WE CAN CONCEIVE THAT SOME OTHER HUMAN BEING COULD READ IN OUR MEMORIES BECAUSE THEY ARE NOT SPATIALLY ATTACHED TO US AND IT SHOULD BE FAIRLY EASY TO CONCEIVE THAT THEIR CONTENTS MIGHT WELL SURVIVE

Note that

There were several transcription errors that did not help in the decryption process. In Message 1, QOEKZ was incorrectly transcribed as QDEKZ and in Message 2 UIOEM was also incorrectly transcribed as VIDEM

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You could find more information here and here if you're interested on the decryption process, or buy Jeff Calof's book online

Answer 2

You were not able to find a solution to Exhibit 5 because it was not "solved" in the usual sense. The plaintext and keys were found through ordinary research and not cryptanalysis. During a visit to the Byrne archive at the National Cryptologic Museum, Jeff Calof discovered a document containing the keys and plaintexts to Exhibit 5, which was prepared by Cryptologia editors Kruh and Deavours. The paywalled article you mentioned must be the paper Calof published to Cryptologia. I would be surprised if the paper did anything other than apply Carl Scheffler's known-plaintext attack to verify the alphabet keys given the plain and ciphertext, or simply re-encipher the given plaintext using the given alphabet keys and compare it to the ciphertext.

You've already seen Moshe Rubin's website, which has a brief article about Calof's find including the document.

I found this information via George Lasry's PhD thesis, "A Methodology for the Cryptanalysis of Classical Ciphers with Search Metaheuristics", which covers his solution to Chaocipher's Exhibit #6 in Chapter 8. Exhibit #6 was solved through a Project Gutenberg search, which I personally think is rather dull.