Claude Fable 5.1 Decodes 370-Year-Old 'Cyphral Distich' Cipher in 44 Minutes

Decoding a 370-Year-Old Cipher

Claude Fable 5.1 decoded the Cyphral Distich cipher found in Sir Thomas Urquhart's work Logopandecteision in 44 minutes. This cipher has attracted academic attention since 1899 and was highly difficult, earning a spot on Klaus Schmeh's 'Top 50 Unsolved Ciphers' list. The original text states that this cipher had been considered 'seemingly unsolved' for centuries.

Decoding Process and Clues

Fable 5.1 reached the solution without external intervention, using 176k tokens over 44 minutes. The model connected Urquhart's 32 Proquiritations located immediately before the cipher text, the fact that each line of the cipher consists of 32 numbers, and the mention of 'wishes' in the poem. Through these clues, it discovered the rule that the numbers point to the Proquiritation numbers, and the first letter of the corresponding number is extracted.

Decoding Results and Verification

The decoded text was a prayer for Charles II, consistent with Urquhart's Royalist political leanings, and was in verse form with each line consisting of exactly 32 characters rhyming with 'and/land'. It also decoded a larger cipher in the same style, the Cyphral Octastich (285 numbers). For the Octastich, 231 of the 275 readable positions matched the first word of the page exactly, while the remaining 44 had differences of 1-3 words, presumed to be transcription or printing errors. The original text noted that due to some page number errors or printing errors, verification of physical copies is necessary for a complete decoding.