Claude Fable 5.1 Decodes a 1653 Encrypted Couplets

Vals AI describes a resolution in 44 minutes and without human assistance of the "Cyphral Distich," a riddle published in 1653 by Sir Thomas Urquhart. The announced method links numbers to words distributed across 32 sections to form a phrase in favor of King Charles II, and relies more on iterative trials than on cryptanalysis.

Vals AI describes a method linking 32 sections for a phrase

According to Vals AI, each number from the two lines corresponds to a word located in one of the 32 sections of Urquhart's work. The initials of these words form the phrase "O God uphold King Charls the Second and make him the supreme ruler of this land." The key to the solution was found within the book itself. Vals AI attributes the success of Fable 5.1 to a systematic method of trial and error and persistence, rather than superior cryptanalysis.

44 minutes without human intervention, after multiple trials

Vals AI specifies that Fable 5.1 generated the solution in 44 minutes, without human intervention. Previously, Vals AI indicates it had spent several months evaluating other advanced models on unsolved riddles, without arriving at a verifiable solution. The team claims to have tasked Fable 5.1 with autonomously identifying a riddle that could be solved; the model then analyzed different problems and selected the "Cyphral Distich." In hindsight, Vals AI believes that humans could have also found this solution.

Urquhart's distich, two lines of 32 numbers published in 1653

The "Cyphral Distich" by Sir Thomas Urquhart was published in 1653 and consists of two lines of 32 numbers. Claude Fable 5.1 is a model developed by Anthropic. This riddle was considered unsolved by researchers prior to this announcement; Fable 5.1 appears to have decoded it, according to Vals AI.