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.