OpenAI's Astra model and Anthropic's Claude Opus 5 model have successfully deciphered a long-unsolved ciphertext encrypted by the Enigma machine during World War II. Developer Carter Leffen used the Astra model to decipher a ciphertext that had stumped researchers since 2005, while cryptanalysis expert Jack Willis used the Claude Opus 5 model to decipher another unsolved ciphertext on September 21. Currently, only seven unsolved ciphertexts encrypted by the Enigma machine remain.