Researchers are applying machine learning techniques to decode historical hand-written ciphers used in medieval correspondence, including diplomatic and personal communications. Whilst not a direct cybersecurity threat, it demonstrates AI’s growing capability to break encryption schemes that were previously considered uncrackable. This has broader implications for understanding how AI might be applied to attack legacy or weak cryptographic implementations.

Architect’s Take: No immediate action required, but treat this as a signal to audit any legacy or non-standard encryption schemes in your environment — if AI can crack medieval ciphers, weak or deprecated algorithms (e.g. DES, MD5, RC4) are increasingly at risk. Ensure your cryptographic inventory is up to date and aligned with current NCSC guidance.

Original advisory: AI Used to Decrypt Medieval Ciphers