Top 10 Unsolved Codes

For much of human history, the written language of the Ancient Egyptians was an enigma. It was only through the discovery of the Rosetta Stone that Jean-François Champollion was able to unlock the secrets of this ancient script. Since then, numerous attempts have been made to decode other ancient languages or break codes created for amusement or profit. Here are the ten most famous ciphers and writing systems that remain unsolved.

10. D’agapeyeff Cipher

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The D’Agapeyeff cipher remains unsolved, appearing in the first edition of 'Codes and Ciphers', a beginner's guide to cryptography by the Russian-born English cartographer Alexander D’Agapeyeff, published in 1939. Presented as a ‘challenge cipher’ at the end of the book, it was omitted from later editions, and D’Agapeyeff is said to have confessed to forgetting how he had encrypted it. Some believe the failure to crack the code is due to D’Agapeyeff having made a mistake in the encryption process, while others think it could still be decrypted through computational methods like genetic algorithms.

Kryptos is an iconic sculpture created by American artist James Sanborn, located at the headquarters of the Central Intelligence Agency (CIA) in Langley, Virginia. Since its unveiling on November 3, 1990, much curiosity has surrounded the encrypted messages embedded in the sculpture. It has become a source of intrigue for CIA staff and cryptanalysts working to crack the code. The ciphertext on one side of the sculpture consists of 869 characters, but in April 2006, Sanborn revealed that a missing letter in the main portion of Kryptos would increase the total count to 870 characters. The other side of the sculpture features a Vigenère encryption tableau, totaling 869 characters when spaces are included. James Gillogly, a computer scientist from southern California, was the first to publicly announce his success in deciphering the first three sections of the sculpture in 1999, cracking 768 characters. The remaining 97 or 98 characters, however, continue to elude both him and government cryptanalysts.

The Shepherd’s Monument at Shugborough Hall features a relief (shown above) depicting a woman observing three shepherds pointing at a tomb. On the tomb, the Latin phrase “Et in arcadia ego” (“I am also in Arcadia” or “I am even in Arcadia”) is inscribed. This relief is based on the famous painting by French artist Nicholas Poussin, also titled Et in Arcadia ego, but with several notable differences—most significantly, the image is reversed horizontally. Additionally, in the sculpture, one shepherd points at the letter N in IN, rather than the R in ARCADIA as in the painting. The sculpture also includes an additional sarcophagus placed atop the one with the Latin inscription. Beneath the image, the following letters are seen:

D  O.U.O.S.V.A.V.V.  M

For those who subscribe to the modern Grail conspiracy theory, this inscription is thought to hold a clue regarding the whereabouts of the Holy Grail. Building on the ideas presented in the book 'The Holy Blood and the Holy Grail,' which claims that Poussin was a member of the Priory of Sion and that his painting contains a hidden message about the Grail’s location, it is believed that the inscription might encode secret knowledge related to the Priory.

In 1933, seven gold bars were reportedly issued to a General Wang in Shanghai, China. These gold bars appear to serve as metal certificates linked to a deposit at a U.S. bank. The bars themselves feature Chinese characters, script writing, and cryptograms in Latin letters. Naturally, there has been some dispute over the legitimacy of the claim for the deposit. Decoding the cryptograms on the bars might help resolve the issue. To date, no theory has been proposed regarding their meaning. The Chinese text has been translated, revealing a transaction exceeding $300,000,000, and referring to the gold bars, which weigh a total of 1.8 kilograms. If you're interested, you can see the cryptograms here and try your hand at cracking the code.

Chaocipher was created by John F. Byrne in 1918, and he spent nearly four decades unsuccessfully attempting to gain the U.S. government’s interest in his cipher system. He even offered a reward to anyone who could break his code, but no one ever claimed it. In 1989, John Byrne, the son of the original inventor, presented Chaocipher to two Cryptologia editors to see if it could have commercial value. After refining the system and providing additional details, they issued a new challenge to would-be solvers. In his autobiography, 'Silent Years,' John F. Byrne, a lifelong friend of James Joyce, dedicated the final chapter to the Chaocipher he had invented in 1918. He recounted his attempts starting in 1920 to interest the State, War, and Navy Departments in his cipher, and his frustration at the lack of interest shown by cryptographic experts like William F. Friedman after he demonstrated his machine.

One of Edward Elgar's most famous compositions is his 'Enigma' Variations, a work that not only showcases his musical genius but also continues to intrigue musical detectives due to the hidden 'secrets' Elgar cleverly embedded within the score. However, Elgar, a man with a passion for codes, ciphers, riddles, and puzzles, left us another mystery—the 'Dorabella' cipher (pictured above). On July 14, 1897, Elgar sent a letter to his young friend Miss Dora Penny, the 22-year-old daughter of the Rev. Alfred Penny, Rector of St Peter’s, Wolverhampton. What made the letter remarkable was that it was written in a cipher, one that, over a century later, still challenges cryptographers. Several attempts have been made to crack the code, but none have provided a definitive solution.

In 1885, a small pamphlet surfaced in Virginia containing a tale and three encrypted messages. The pamphlet told the story of a man named Beale, who, around 1820, allegedly buried two full wagons of treasure at a secret location in Bedford County, Virginia. Beale then left a small locked box with a local innkeeper and disappeared without a trace. Years later, the innkeeper, after receiving no further word from Beale, opened the box to find encrypted messages inside. Unable to decipher them, he passed the box on to a young friend just before his death in 1863. The pamphlet claims the friend spent the following 20 years attempting to crack the codes, managing to decipher only one, which described the treasure—gold, silver, and jewels—and a general location. The remaining unsolved messages, according to the pamphlet, contain precise directions and a list of the treasure's rightful owners. Despite numerous extensive searches for the treasure and efforts to decode the messages, no confirmed decryption has been achieved. Many solutions have been proposed, often paired with a book for sale, but no one has ever produced a replicable decryption method.

Linear A is one of two linear scripts used in ancient Crete, alongside Cretan Hieroglyphs, and was discovered and named by Arthur Evans. Linear B, a related script, was deciphered by Michael Ventris in 1952 and was used for Mycenaean Greek. While Linear A remains largely undeciphered, parts of it have been understood and it may be read by applying the values from Linear B. Despite sharing many symbols, the syllables from Linear B in Linear A inscriptions yield words that don't correspond to any known language. This script is thought to represent the Minoan or Eteocretan language, associated with a period of Cretan history prior to the invasions of the Mycenean Greeks around 1450 BC. Some scholars believe there may be a connection between Linear A and the Phaistos Disk.

Dating back at least 400 years, the Voynich Manuscript is a 232-page book entirely written in an unknown script. It is filled with intricate drawings of mysterious plants, herbal recipes, astrological charts, and numerous small human figures trapped in odd, plumbing-like contraptions. The script used is unlike any other known writing system, yet it appears to have been written confidently by someone familiar with it. In 2004, some persuasive arguments suggested techniques that might prove the manuscript was a hoax, but to this day, no one has been able to replicate any part of the manuscript using those methods. Over the years, the Voynich Manuscript has attracted the attention of both professional and amateur cryptographers, including top British and American codebreakers from World War II—none of whom were able to decipher a single word. These consistent failures have made the Voynich Manuscript one of the most famous unsolved mysteries in the field of historical cryptology.

The Phaistos Disc stands as the most significant example of hieroglyphic writing from Crete. It was unearthed in 1903 in a small chamber near the “archive room” within the northeast section of the palace. Alongside the disc, a Linear A tablet and pottery dating from the early Neo-palatial period (1700-1600 B.C.) were discovered. Both sides of this clay disc are inscribed with hieroglyphs arranged in a spiral pattern, pressed into the clay while it was still wet. The symbols are grouped and separated by vertical lines, and each group is believed to represent a word. A total of 45 different symbols have been identified, some of which resemble hieroglyphs from the Proto-palatial era. Some sequences repeat like refrains, hinting at a religious chant, while Pernier suggests the text may be ritualistic in nature. Others speculate that the disc could be a list of soldiers or even a Hittite language document, where a king discusses the construction of the Phaistos Palace.

Notable Omissions: Zodiac Killer ciphers (some remain unsolved, but their authenticity has been questioned).

Sources: Wikipedia