The top 10 unsolved ciphertexts

Filed Under: Cryptography, Featured

For over 12 centuries an intense battle has been fought between the code-makers and the code-breakers.

We previously talked about some ciphers that have been defeated and the impact it had. However, despite decades (or centuries!) of cryptanalysis there are many ciphertexts which still successfully conceal their contents.

Here's a roundup of my top ten, with links to groups actively tackling them provided where possible.

  1. Dorabella – 1897, Wolverhampton, UK, Yahoo! Group

    The Enigma Variations isn't the only cryptic legacy of the renowned English composer Sir Edward Elgar. In a letter sent to his close friend Dora Penny (‘Dorabella’) Elgar included an encrypted message consisting of 87 symbols.

    Dorabella cipher

    Dorabella was never able to understand the message herself and despite a couple of decryptions being proposed over the years, there is no universally accepted solution.

    The same symbols have also been found on a 1886 Liszt concert programme of Elgar’s (the ‘Liszt fragment’) which suggest perhaps a musical solution, though a 1920’s notebook of his contains the same symbols and practice attempts at encryption.

    Other symbols found on these pages could contain the key to decryption.

  2. Beale Papers – 1885, Virginia, US

    Legend tells us of three ciphertexts published in an 1885 pamphlet by an anonymous author, which reveals the location of hidden treasure discovered by Thomas J. Beale and buried somewhere in Virginia in 1820.

    The author depicts the story of the gold discovery, how they came into possession of the three messages, and how they cracked the second of these. They show that this second message is a book cipher with the American Declaration of Independence as the key and the decryption of it outlines the contents of the treasure (worth around $20 million).

    Treasure hunters should note, however, that textual analysis of the pamphlet suggests that both the pamphlet and the ciphertexts were written by the same person, leading many people suspect it to be a hoax.

  3. The Zodiac Killer – 1968-9, Northern California, US

    The identity of a serial killer responsible for attacks against of at least four men and three woman in the US, is unknown to this day. During the period of these attacks, the self-dubbed 'Zodiac' sent a series of taunting messages to the police and newspapers which contained a total of four ciphertexts.

    Zodiac Killer cipher

    One of these has been decrypted and was shown to be a homophonic substitution cipher (multiple symbols per letter) using 57 symbols to encrypt 23 different letters. Warning: Explicit themes below.

    I LIKE KILLING PEOPLE BECAUSE IT IS SO MUCH FUN IT IS MORE FUN THAN KILLING WILD GAME IN THE FORREST BECAUSE MAN IS THE MOST DANGEROUE ANAMAL OF ALL TO KILL SOMETHING GIVES ME THE MOST THRILLING EXPERENCE IT IS EVEN BETTER THAN GETTING YOUR ROCKS OFF WITH A GIRL THE BEST PART OF IT IS THAE WHEN I DIE I WILL BE REBORN IN PARADICE AND THEI HAVE KILLED WILL BECOME MY SLAVES I WILL NOT GIVE YOU MY NAME BECAUSE YOU WILL TRY TO SLOI DOWN OR ATOP MY COLLECTIOG OF SLAVES FOR MY AFTERLIFE ABEORIETEMETHHPITI

    (Original typos included.)

    The meaning of the last 18 letters is unclear, and the remaining three ciphertexts have never been successfully decrypted. The messages sent from the Zodiac at this time are clearly authentic, and cracking the other ciphertexts could finally reveal the killer's identity.

  4. Ricky McCormick's Notes – 1999, Missouri, US

    Here's another case of an unsolved cipher which could lead to the identification of a murderer. In June 1999, the body of 41-year-old Ricky McCormick was discovered in a cornfield in Missouri, US. Twelve years later, it came to light that two encrypted notes were found in his pockets.

    Ricky McCormick's notes

    Though considered by the FBI as a homicide, McCormick's killer has never been caught nor the notes decrypted. None of McCormick's family members know how to read his notes, and in the words of FBI crypto-chief Dan Olson, “We are really good at what we do, but we could use some help with this one.”

    Anyone with information on how to crack the cipher should submit their ideas directly to the FBI.

  5. Voynich Manuscript – 15th Century, Italy

    Purchased by book dealer Wilfrid Voynich in 1912, the 240-page Voynich manuscript has been labelled one of the world's most mysterious manuscripts.

    Voynich Manuscript

    It consists of six distinct sections, containing undecipherable text alongside herbal, astronomical, biological, cosmological and pharmaceutical illustrations.

    The text uses over 170,000 symbols and displays statistical properties akin to that of natural languages. While further statistical analyses point towards the manuscript being a hoax, it is generally considered that it is too elaborate for this to be the case.

    Either way, the Voynich manuscript has attracted the attention of many cryptanalysts over the years, most notably the military cryptanalyst William Friedman.

  6. Linear A – Ancient Crete, 18th Century BCE

    Linear A is one of over 25 writing systems that, unlike Hieroglyphics, remain undecipherable.

    Linear A

    Clay tablets unearthed by archaeologists on the Greek island of Crete hint at an ancient Minoan empire, possibly the origins of the Greek legend 'Theseus and the Minotaur'.

    Symbols from one set of tablets (dating from 1450 to 1375 BCE) are from a language known as Linear B, of which a decipherment was finally published in 1953. The decipherment of an older set of tablets (dating from 1750 to 1450 BCE) has never been accomplished.

    These inscriptions, dubbed Linear A, are clearly the written system that Linear B was derived from, yet the understanding of Linear B sheds no light on Linear A.

  7. D'Agapeyeff Cipher – 1939, Oxford, UK, Yahoo! Group

    It is somewhat of a tradition for books on the topic of cryptology to contain a cipher left as a challenge to readers. The cipher challenge published in D'Agapeyeff's Codes and Cipher remains unsolved.

    Ignoring the final three zeros as padding, the message consists of 196 (14²) two-digit pairs, the first digit being one of {6, 7, 8, 9, 0} and the second being one of {1, 2, 3, 4, 5}. This allows for encryption of 25 letters (5x5 matrix) and should be fairly straightforward to crack.

    D'Agapeyeff, however, later admitted to having forgotten how he encrypted his impenetrable message and the cipher was removed from future editions of the book. It is very likely that the message has never been cracked due to errors in the encryption.

  8. Kryptos – 1990, CIA Headquarters, US, Yahoo! Group

    Another cipher challenge lies in the grounds of the US Central Intelligence Agency; a cryptographic sculpture designed by artist Jim Sanborn and placed there in 1990.

    Kryptos falls into the category of 'partially solved', with three ciphertexts having been cracked but the fourth and final remaining a mystery and actively pursued by amateur and professional cryptanalysts alike.

    The first two are encrypted with the Vigenère polyalphabetic substitution ciphers, while the third is an elaborate transposition cipher. These first three ciphers allegedly contain a clue to unlock the elusive final cipher.

    Kryptos has since been referenced in popular culture multiple times (it is used as a theme in Dan Brown's The Lost Symbol) and is set to continue to baffle intellectual minds for many years to come.

  9. Blitz Ciphers – World War II, London, UK

    All of the ciphertexts discussed so far are well documented and have been analysed by many over the years. On the contrary, there is little known about the so called 'Blitz' ciphers discovered during World War II in a bombed cellar in East London, UK, but only recently published last January.

    Photographs taken of some of the papers found in a wooden box concealed in the cellar wall show around 50 distinct calligraphic symbols. The origins of these cryptic documents are unknown, though it is speculated that they could potentially be 18th century Freemason ciphers.

    More information and analysis is definitely required to rule out possibility of it being another a hoax.

  10. D-Day Pigeon – June 6th, 1944, France

    Last November, the remains of a messenger pigeon were discovered in a chimney in Surrey, UK, with the attached message intact.

    D-Day Pigeon

    The message, addressed to ‘X02’ from ‘W Stot Sjt.', consists of 27 five-letter groups and is one of two duplicate messages sent from Nazi-occupied France during the D-Day landings.

    The encryption used most likely relies on a codebook with each group of letters having a specific meaning. The message was possibly also super-enciphered (cipher of a cipher) with a one-time pad (theoretically unbreakable cipher).

    This means without the authentic cryptographic material used at the time it is impossible to verify a proposed decryption.

    The official statement from GCHQ reads, "Hundreds of these proposed solutions have been carefully examined by our expert cryptanalysts at GCHQ. So far none have proved credible.”

Leave a comment below, or tweet me @julianbhardwaj with your ideas on how/if any of these ciphertexts could ever be solved!


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9 Responses to The top 10 unsolved ciphertexts

  1. Kimberly Truong · 601 days ago

    Really enjoyed this article, Julian. I love unsolved mystery stories... and theories. :)

  2. gman · 601 days ago

    I dig your articles. They should let you do more!

  3. Joe · 598 days ago

    I tried working the RIcky McCormick text in 2011, I was told it was solved. It was a recipe for Methamphetamine.

  4. Steely · 598 days ago

    Great article. Uncracked ciphertexts have always been fascinating to me. I do wonder how many of them are one-time pads and therefore unlikely to be solved (impossible to solve?).

    Another great unsolved ciphertext is the code in the Taman Shud (Somerton Man). In that case, an unidentified man was found dead of undetermined cause - believed to be some form of poison - on a beach in Adelaide, Australia. A scrap of paper was found on the corpse with the words "Tamam Shud" printed on it. The scrap was traced back to a book - a copy of a translation of The Rubaiyat by Omar Khayyam. The book contained the following ciphertext:

    WRGOABABD
    MLIAOI (*This was crossed through in the original ciphertext)
    WTBIMPANETP
    MLIABOAIAQC
    ITTMTSAMSTGAB

    As far as I know, this has never been cracked.

  5. guest · 598 days ago

    I've always enjoyed how these artifacts of history have such colorful stories attached to them. They're interesting even if a hoax or the ravings of a madman (that's always been my theory regarding the Zodiac Killer's "ciphers" -- you can't decipher psychosis from just a string of characters).

    • Zodiac's a coward · 578 days ago

      I find it hard to believe that after all these years and failed attempts to crack the Zodiac's 340 symbol cipher, people still believe that he actually included his identity in the cryptogram. Zodiac is a coward. He claimed his ID was included in the 408 (which was solved, and in the solution he says "I won't tell you my name"). Even if the 340 is ever solved, it's not going to contain Zodiac's real name IMHO. He's a murderer and an even bigger coward and would never reveal his ID .

  6. Phil · 151 days ago

    D day pigeon code has been solved

    • Paul Ducklin · 151 days ago

      Or not. If you're talking about the Canadians who claimed to have solved it some time at the end of 2012, then it looks very much as though they were hoaxing.

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About the author

Julian Bhardwaj is currently a student at the University of Warwick studying for an undergraduate degree in Discrete Mathematics. As a self confessed crypto-geek, he has a passion for all things security related.