Fable 5.1 Solves the Cyphral Distich, a 370-year-old cipher

	Fable 5.1 Solves the Cyphral Distich, a 370-year-old cipher(vals.ai)
	1056 points by u1hcw9nx 15 hours ago \| 468 comments
	tl;dr: Claude Fable 5.1 solved Sir Thomas Urquhart's 370-year-old Cyphral Distich cipher by recognizing that the key was the book itself: each of the 64 numbers indexes a word in one of Urquhart's 32 Proquiritations, with the first letter forming a royalist prayer for Charles II. The model then applied the same technique (using page numbers instead of paragraphs) to largely decode Urquhart's longer Cyphral Octastich from The Jewel (1652). The author argues this shows LLMs can crack historical puzzles bottlenecked less by cryptanalytic difficulty than by sustained human attention.
	HN Discussion: ↓The cipher was already suspected to be a book cipher by prior commenters, undermining the article's novelty claim ↓The article overstates the difficulty and prior study of this cipher, misleadingly framing the LLM's achievement ~Recent LLM cipher successes reflect low-hanging fruit ignored by humans rather than genuine cryptanalytic capability ↓Selection bias: LLMs pick problems they can solve, so impressive-looking results don't prove general capability ↑Personal anecdote confirms LLMs can genuinely crack real ciphers with unknown keys