Discover the Copiale Cipher: The Mysterious 18th-Century Book That Took 260 Years to Decode

Discover the Copiale Cipher: The Mysterious 18th-Century Book That Took 260 Years to Decode In the world of cryptography, substitution ciphers are child’s play. Indeed, we may remember literally playing with them as children, writing secret messages to our friends by replacing all the letters with numbers, say, or shifting them one or two places over in alphabetical order. Cracking such codes was a trivial matter even before the computer age, but certain simple variations could make them more robust. Take the document known as the Copiale cipher (downloadable as a two-part PDF), a 105-page bound manuscript that stayed undecipherable for more than 260 years. Its mystery finally yielded to the efforts of University of Southern California computer scientist Kevin Knight and Uppsala University linguists Beata Megyesi and Christiane Schaefer only in the early twenty-tens. As Tommie Trelawny tells the story of the Copiale cipher in the Hochelaga video above, the manuscript, which was

Added 1 May 2026