8 of History’s Most Mysterious Uncracked Codes

History is filled with enigmatic codes that remain unsolved. While some code creators are still alive to provide hints, others have been around for centuries, leaving experts to depend solely on historical records for insights. From perplexing ciphers discovered on a murder victim to the unresolved codex once owned by Holy Roman Emperor Rudolf II, here are several codes that continue to baffle cryptologists, inspired by an episode of The List Show on YouTube.

1. Rapa Nui’s Rongorongo  

During the early 1860s, Rapa Nui—now called Easter Island—was invaded by raiders who captured hundreds of its inhabitants, forcing them into slavery in Peru. It was widely believed that these raids erased the last traces of understanding about rongorongo, the island’s hieroglyphic script. However, while the texts remain undeciphered to this day, the story of this enigmatic language is far more complex than it initially appears. 

The notion that rongorongo’s knowledge vanished during the 1862 and 1863 raids has been heavily questioned. However, it is likely that those fluent in the script perished during that decade, possibly due to diseases brought to the island by European settlers. 

Numerous rongorongo artifacts were lost in the 1860s. These inscriptions, often etched into wood, were reportedly burned by the Rapa Nui people for firewood. Some accounts suggest this was encouraged or forced by Catholic missionaries, who allegedly viewed rongorongo as a link to pagan beliefs. Others contested this narrative. A European priest in the early 20th century theorized that the artifacts were not destroyed but concealed in the island’s caves and lava tubes, as detailed in Steven R. Fischer’s 1997 book on the subject. 

A few dozen rongorongo inscriptions have survived, and efforts to decode their symbols have persisted for over a century with little success. Some glyphs depict human or animal figures, while others are abstract designs. No credible translation has been proposed, and the origins of the script remain hotly debated. Theories range from pre-European origins to speculative ideas involving extraterrestrials and ancient civilizations. 

Our understanding of rongorongo has been shaped by credible research, including the work of Katherine Routledge, an early 20th-century ethnographer. In 1914, Routledge traveled to Easter Island and spoke with elders whose knowledge extended back to the 1850s. One of the most fascinating revelations from her interviews was that, according to her sources, young Rapa Nui students in the past could learn rongorongo within a matter of months. 

2. The Beale Ciphers

Thomas J. Beale allegedly buried a treasure in Bedford, Virginia, after finding gold and silver in what is now the American west. The key to locating it? Simply decipher a straightforward code. 

However, this claim originates from the 1885 publication “Beale Papers,” released long after Beale vanished. Beyond this, there is little consensus—whether Beale truly left behind a treasure or even created the ciphers remains hotly debated.

Certain historical details of Beale’s alleged adventures have been disputed. For instance, his supposed discovery of silver and gold doesn’t align with established timelines of other precious metal findings. Many Beale Cipher enthusiasts offer unique theories to explain these discrepancies, while others argue that even if the treasure is a fabrication, the ciphers might still pose a genuine cryptographic puzzle waiting to be solved.

William Friedman, a renowned cryptanalyst, encapsulated the mystery surrounding the Beale Ciphers with his statement: “On Mondays, Wednesdays, and Fridays, I believe it’s genuine. On Tuesdays, Thursdays, and Saturdays, I’m convinced it’s a hoax.”  

3. The Voynich Manuscript

When a manuscript reportedly transitions from an astrologer to the Holy Roman Emperor, a sense of mystery is inevitable. The Voynich Manuscript—named after a Polish antiquarian who acquired it in 1912—lives up to its enigmatic reputation. 

After Wilfrid Voynich obtained the manuscript in the early 20th century, he asserted that he was bound by secrecy concerning its origins. It is believed to have a link to Holy Roman Emperor Rudolf II, whom Voynich claimed received it from John Dee, an astrologer in Elizabeth I’s court. (However, this origin story is now widely doubted.)

The manuscript’s pages are filled with illustrations resembling plants, along with scientific or pseudoscientific diagrams and numerous depictions of women bathing. The text, comprising around 35,000 words, seems entirely fabricated—not only the words but also the characters themselves. 

Radiocarbon dating conducted by a team led by Greg Hodgins from the University of Arizona dated the pages to the early 15th century. Yet, the author and purpose of the book remain unknown. Many top codebreakers, including William and Elizebeth Friedman, a renowned cryptanalyst couple (William also tackled the Beale Ciphers), have attempted to decipher it without success. The Friedmans analyzed the manuscript and concluded it was authentic, not a forgery. By the end of his life, William believed it was less of a code and more “an early effort to create an artificial or universal language of the a priori type”—a language independent of existing tongues.

In the absence of a definitive explanation, numerous wild theories have emerged. Voynich once declared, “When the time comes, I will prove that the so-called black magic of the Middle Ages was actually advanced scientific knowledge far ahead of 20th-century science.” That moment never arrived, and his bold statement may have been mere theatrics. 

Despite this, countless theories about the manuscript’s true purpose persist. One widely held belief is that it holds no meaning at all—that, contrary to the Friedmans’ findings, the manuscript was crafted as a hoax, possibly to deceive Emperor Rudolf. 

4. The Dorabella Cipher

Another unsolved—and possibly unsolvable—cipher originates from Edward Elgar. If the name rings a bell, it’s likely because Elgar composed “Pomp and Circumstance,” the second most famous graduation anthem in history. 

Named after its intended recipient, Dora Penny, a friend of Elgar’s who was nearly 20 years younger, the Dorabella Cipher features a sequence of curly, enigmatic characters. While several individuals have claimed to decode Elgar’s cipher, none of these solutions has gained widespread acceptance.

Tim S. Roberts from the University of Central Queensland in Australia believed he had deciphered the cipher, producing the text: “P.S. Now droop beige weeds set in it—pure idiocy—one entire bed! Luigi Ccibunud lovingly tuned liuto studio two.” The first part might possibly relate to gardening, as Roberts suggested, but the mention of “Luigi Ccibunud” requires accepting that Elgar was referencing an Italian composer and mocking Dora’s stutter while discussing plants. Other proposed solutions either rely on arbitrary rules or result in nonsensical text, leaving Elgar’s true message a mystery. 

5. The Feynman Challenge Ciphers

In 1987, Chris Cole shared three ciphers on a usenet newsgroup focused on cryptography. According to his post, Dr. Richard Feynman had presented these ciphers to him during Cole’s time as a graduate student at Caltech. While the first cipher was solved within a day by a Usenet user, the other two remain unsolved to this day.

6. Kryptos Section Four

One might assume that placing a code on the CIA headquarters’ grounds would lead to a swift solution. Yet, despite numerous U.S. intelligence officers walking past the Kryptos sculpture daily on their way to the cafeteria in Langley, Virginia, one section of the code remains unsolved—even after the creator has offered multiple hints to cryptologists over the years. 

Kryptos, crafted by artist Jim Sanborn, was installed at Langley in 1990. Over time, three of its four coded sections were deciphered. The first section unveiled a poetic line by Sanborn: “Between subtle shading and the absence of light lies the nuance of iqlusion.” Sanborn intentionally misspelled “illusion” to add an element of unpredictability.

The second section contains a cryptic paragraph mentioning Langley’s coordinates and former CIA director William Webster, who led the agency during the sculpture’s installation. The third section rephrases Howard Carter’s description of uncovering King Tut’s tomb in 1922. 

Sanborn has hinted that the first three sections hold clues to solving the fourth. He has also revealed specific words from the final section, including Berlin, clock, and northeast. 

7. Tamám Shud

In 1948, a man’s body was discovered on Somerton beach in Australia. Dressed in a suit, a half-smoked cigarette was found on his collar. As investigators delved deeper, the case grew increasingly bizarre. 

Authorities were unable to identify the deceased or determine the cause of death. Some speculated that a rare poison, which left no trace after being metabolized, might have killed him. The man’s unusually prominent calf muscles and a clothing label reading “Keane” could have been significant clues or mere distractions—no matching “Keane” was ever found, and theories about him being a dancer or wearing high heels remain unproven.

Months into the investigation, John Cleland, an expert, found a small piece of paper in a hidden pocket of the man’s trousers. The paper bore the Persian phrase tamám shud, meaning “it is ended”—a phrase that concludes many translations of The Rubáiyát of Omar Khayyám.

It took months for someone to produce a matching copy of the book, which only deepened the mystery. On the back cover of the book—its origins also unclear—investigators discovered a phone number and a faint sequence of characters. The phone number led to a woman who admitted giving a man named Alfred Boxall a copy of The Rubaiyat, but Boxall was alive and still in possession of his book. 

Investigators revisited the mysterious string of characters and examined it under ultraviolet light, uncovering additional letters that seemed to form a cipher. If it is indeed a code, it has never been deciphered—and, given the limited number of letters, it may remain unsolved forever. Strangely, no other copy of The Rubaiyat matching the edition found on the deceased has ever been located.

Some believe the Somerton man took his own life, while others suspect he was killed due to involvement in high-level espionage. Although the truth may never be uncovered, in 2021, his body was exhumed for DNA analysis; separate tests using material from his death mask connected him to an Australian man named Carl Webb.

8.  Ricky McCormick’s Notes

When Ricky McCormick’s body, a potential homicide victim, was found in June 1999, authorities discovered two handwritten notes in his pockets containing an incomprehensible sequence of letters.  

McCormick was reportedly functionally illiterate. His mother, Frankie Sparks, stated, “The only thing he could write was his name. He didn’t write in any code.” However, officials believe the notes are not random scribbles—they even released the potential ciphers to the public in 2011, hoping someone could help decode them. 

McCormick’s girlfriend speculated that he might have been involved in marijuana trafficking. He also suffered from various health issues, possibly linked to his smoking habit—reportedly starting at age 10—and his habit of consuming over 20 caffeinated drinks daily. While a natural cause of death cannot be dismissed, McCormick’s alleged ties to illegal activities and the enigmatic nature of his death have led many to suspect foul play.

Detective Michael Yarbrough, who once handled the case, described the baffling complexity of the situation to St. Louis’s Riverfront Times: “It’s like Humpty Dumpty. All the pieces are there, but how do you put them back together?”