The Top 50 unsolved encrypted messages

The following list is a compilation of the 50 most important unsolved cryptograms.


50. Cylob cryptogram


Number 50 is the Cylob cryptogram, a truly mysterious book.


49. The Chinese goldbar cryptogram

Seven Chinese goldbars  from the 1930s bear encrypted inscriptions that have never been deciphered. The provenance of these goldbars is a mystery, too.


48. Ron Rivest’s timelock cryptogram

In 1999 cryptographer Ron Rivest published an encrypted text that was designed to take 35 years to break. 18 years later it is still unbroken.


47. Encrypted messages of a Nazi spy

In 1944 a Nazi spy located in New York sent encrypted messages via Paris to Germany. These cryptograms have never been deciphered.


46. Unsolved ADFGVX cryptograms from World War 1

ADFGVX is an encryption method used by the Germans in WW1. Some 20 ADFGVX radio messages from 1918 are still unsolved.


45. The World Record Challenge

The longest key ever publicly broken by exhaustive key search has 64 bits. A challenge I created a few years ago aims to improve this world record by one bit.


44. A WW2 encryption hidden in a bullet

Two years ago a detectorist found an encrypted note hidden in a WW2 bullet in central Italy. Despite many tries this cryptogram is still unsolved.


43. The Rayburn murder cryptogram

US citizen David Rayburn killed his wife, his step-son, and himself. Years later, an encrypted text allegedly written by him emerged. This cryptogram is unsolved to this day.


42. The Bonus 22 challenge

The M-209 is a small and robust encryption machine used by the US Army in World War II. Although several cryptologists have developed powerful methods to break the M-209, one series of messages is still unsolved.


41. The Blitz ciphers

The Blitz Ciphers are an encrypted book allegedly found in London just after World War II. Only eight page scans have been published. Some of my readers consider the Blitz Ciphers a fake.


40. The Beale cryptograms

The Beale cryptograms are the greatest hoax in crypto history. Generations of treasure hunters have tried to solve them and to find the hidden treasure, the location of which they allegedly describe. Nobody has ever been successfull, as the treasure simply does not exist.


39. The Riverbanks Ripper cryptograms

The Riverbanks Ripper was a serial murderer, who killed nine people in the 1970s. He was never identified. At one of the crime scenes he left behind an encrypted note that is unsolved to date.


38. The Sufi Fiddle mystery

An inscription found on the inside of an old fiddle has never been deciphered.


37. The Shugborough inscription

An 18th century monument in Shugborough Hall near Birmingham, UK, bears an inscription consisting of ten letters. This message is one of the world’s most famous unsolved ciphertexts.


36. The Fair Game code

In the end credits of the movie Fair Game (2010) some letters are marked yellow. Do they form a code? If so, the solution is unknown.


35. Cryptograms from the crypt

British psychologist and parapsychologist Robert Thouless (1894-1984) published a short cryptogram. He intended to channel the key after his decease from the realm of the dead. So far, this experiment has failed. Thouless’ cryptogram is still unsolved.


34. Unsolved nomenclators

For centuries nomenclators were the most popular kind of encryption. Still today messages enciphered with a well-designed nomenclator are hard or even impossible to break.


33. The censorship manual steganograms

In a British censorship manual from WW2 two pictures containing hidden messages are displayed. Many have tried to find these messages, but up until now with no success.


32. The silk dress cryptogram

In 2014 Maryland-based costume collector Sara Rivers-Cofield discovered an encrypted note in an antique silk dress. This cryptogram is unsolved to date.


31. The MLH cryptogram

A young man, who had disappeared from his home in California, sent an encrypted message from Israel to his parents. This cryptogram has been unsolved for over four decades. Can a reader decipher it?


30. The Harry-Caroline and the Tissie Jabber messages

Tissie and Jabber as well as Harry and Caroline were two amorous couples, who exchanged encrypted messages via newspaper ads more than a century ago. Their encryption codes are unsolved to date.


29. The Pollaky cryptograms

British private detective Ignatius Pollaky (1828-1918) published a number of encrypted newspaper ads. Some of them have never been solved.


28. Thomas Urquhart’s encrypted poems

Scotish poet Thomas Urquhart (1611-1660) left behind two encrypted poems. They have never been deciphered.


27. Ferdinand III’s encrypted letters

During the Thirty Years’ War emperor Ferdinand III (1608 -1657) used a secret writing system. It has never been solved.


26. The Dorabella cryptogram

The Dorabella Cipher is one of the most popular crypto mysteries in the world. 120 years after its creation still nobody has found the solution.


25. The SS radio message

In 1944 a member of Hitler’s paramilitary organization SS sent an encrypted radio message to a recipient named Lippert. The cleartext is unknown.


24. The Erba murder cryptogram

In 2006 a couple from Erba, Italy, murdered four neighbors. An encrypted letter from this criminal case is still waiting to be solved.


23. The Copenhagen cryptogram

For decades, members of the American Cryptogram Association have tried to decipher an encrypted note found in Denmark – but to no avail.


22. The Powers cryptogram

The best-selling novel “The Gold Bug Variations” from 1991 contains an encrypted dedication. It has never been deciphered.


21. The YOG’TZE case

In October 1984 unemployed German food engineer Günther Stoll died of murder or accident. Shortly before his death he had written the word YOG’TZE on a piece of paper. Neither the reason of Stoll’s death nor the meaning of YOG’TZE has ever been found out.


20. The pigeon cryptogram

Five years ago an encrypted carrier pigeon message from World War II hit the news. So far, nobody has been able to decipher it.


19. The Kaliningrad bottle post

Two years ago an encrypted bottle post was found in Kaliningrad, Russia. Can a reader break this cryptogram?


18. The Moustier Altar Inscriptions

The encrypted altar inscriptions of Moustier, Belgium, have been puzzling codebreakers for 170 years.


17. The Roosevelt cryptogram

In 1935 US president Franklin D. Roosevelt received an encrypted letter from an anonymous person. The solution of the main part is not known.


16. The train station robbery cryptogram

In 1916 an unknown man robbed a ticket counter at the train station of Lima, Ohio. According to a local newspaper he left behind an encrypted message, the purpose of which is unknown. The message has never been deciphered.


15. The Rilke cryptogram

During the Second World War, an unknown person stuck sheets with seemingly random letter sequences into a book. The meaning of these letters is unknown.


14. The Codex Seraphinianus

The Codex Seraphinianus is an unusual book, a beautiful artwork, and an unsolved crypto mystery. It’s the Voynich Manuscript of the 20th century.


13. The Double Column Transosition challenge

In 2013 George Lasry broke a ciphertext many had considered unbreakable. In the wake of this success, a few crypto experts created a similar challenge with an even higher level of difficulty. Is this one unbreakable? So far, nobody has solved it.


12. The Scorpion letters

In 1991, an unknown person sent a number of letters to the presenter of the TV show “America’s Most Wanted”. The anonymous writer claimed to have committed 23 crimes. Some of the letters were encrypted in a similar style as the Zodiac Killer messages.


11. The Untersberg code

According to a legend, an encrypted message was found in a cave of the Untersberg, a mountain in the Northern Alps. The cleartext is not known.


10. Ricky McCormick’s encrypted notes

Murder victim Ricky McCormick left behind two encrypted notes. Both the crime and the cryptograms are unsolved to date.


9. The Rubin cryptogram

18-year-old chemistry student Paul Rubin was found dead with a cyanide poisoning in 1953. In his possession police found an encrypted message. This cryptogram has never been deciphered.


8. The Catokwakopa cryptograms

Two encrypted newspaper advertisements from 1875 are still unsoved. Is the first one the key to the second?


7. The cigaret case cryptogram


6. The Rohonc Codex

Two encrypted newspaper advertisements from 1875 are still unsoved. Is the first one the key to the second?


5. The Somerton Man

A dead man who was found in Australia in 1948 has never been identified. An encrypted (?) text could help solve the mystery. But nobody has been able to decipher it yet.


4. Kryptos

The encrypted inscription on the Kryptos sculpture located in front of the CIA building in Langley, Virginia, is the world’s most famous crypto puzzle.


3. Debosnys cryptograms

Henry Debosnys (1836-1883), a convicted murderer, left behind four cryptograms, which  are unsolved to date. Breaking them could shed light on the many mysteries that surround this case.


2. Zodiac Killer cryptograms

The Zodiac Killer murdered five or more people and sent four encrypted messages to newspapers. The case and three of the cryptograms have never been solved.


1. The Voynich Manuscript

The Voynich Manuscript is the most famous unsolved crypto mystery in the world. For this reason, I put it at the first position of my top 50 list.