A new AI model, Claude Fable 5.1, developed by Anthropic, has successfully deciphered the "Cyphral Distich," a cryptic code consisting of two lines of 32 digits each. This code had puzzled cryptographers for over 373 years, since its creation in 1653. Vals AI, a company that specializes in testing AI models, reported that the model took 44 minutes and processed 174,000 tokens to decode the message. The decrypted message reads: "O God, support King Charles II and make him the supreme sovereign of this country." The breakthrough highlights the growing capabilities of AI in solving historical and cryptographic challenges. Anthropic is an American public interest company based in San Francisco, California, focused on developing artificial intelligence (AI) with a strong emphasis on safety. The company was founded in 2021 by former members of OpenAI, including Daniela Amodei, who serves as president, and her brother Dario Amodei, the CEO. Anthropic's flagship product is the Claude series of large language models (LLM), which are available through an online chatbot, API, and various tools such as Claude Code, Cowork, Design, and Science. These models are designed for a range of applications, from coding assistance to scientific research. In early September 2026, Anthropic launched two updated versions of its models: Claude Fable 5.1 and Mythos 5.1. These versions include improved security features and reduce cache reading costs by 75%, making them more efficient and cost-effective for developers. The models scored 52.6% in a scientific research performance test, compared to 24.7% for previous versions. The new models also include a watermark compliant with the European Union's AI Act, and the detection API is now in private beta for selected organizations. The cost reduction is a major selling point, with cache reads now priced at $0.25 per million tokens, cutting typical workloads by 25% and agent-like tasks by up to 45%. The "Cyphral Distich" was created by Thomas Urquhart, a Scottish writer and polymath, in 1653. Urquhart was known for his ambitious projects, including the creation of a complex artificial language called "Logopandecteision." This language was designed with an intricate grammar system, including twelve grammatical categories, each with multiple cases, numbers, and genders. Urquhart claimed his language could translate verses from various European languages, including Italian, French, Spanish, and English. The Cyphral Distich, however, was a cipher rather than a language. It was described in 1899 as an unsolvable problem and later included in a list of the 50 most famous undeciphered messages by the historian Klaus Schmeh. The AI model identified 32 short wishes, or "provirations," that preceded the code and used them to decode the message by associating each digit with a specific word and taking its first letter.