Claude Fable 5. 1 deciphers 370-year-old Cyphral Distich cipher

The AI model Claude Fable 5. 1 has successfully decrypted the Cyphral Distich, a historical cipher created by Scottish writer Sir Thomas Urquhart in 1653 that had remained unsolved for over 370 years.

Conducted by the U.S.-based organization VALS AI, the decryption process took approximately 44 minutes and utilized roughly 176,000 tokens. The cipher, which appears at the end of Urquhart’s work ‘Logopandecteision’, consists of two sequences of 32 numbers, totaling 64 values. While traditional methods like frequency analysis and homophonic substitution failed to crack the code, the AI identified a pattern linked to the structure of the book itself.

The model deduced that the key was not an external cryptographic system but was embedded in the text. By connecting the significance of the number 32—noted in Urquhart’s ‘32 Proquiritations’—with thematic references to ‘wishes’ in the accompanying poem, the AI discovered a rule: for the i-th number (n) in the sequence, the solution is the first letter of the n-th word in the i-th Proquiritation.