Research · curated 28 Jul 2026
Discovering cryptographic weaknesses with Claude
First reported · updated · 3 reports anthropic.com
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Why it matters
Claude Mythos autonomously improving on cryptanalysis that survived years of expert human review signals that frontier AI models are becoming capable offensive research tools, foreshadowing AI-driven discovery of real-world cryptographic and software weaknesses defenders will need to anticipate.
Anthropic's Frontier Red Team reports that Claude Mythos Preview autonomously discovered improved cryptographic attacks: an attack that roughly halves the key strength of the post-quantum signature candidate HAWK, and a new attack on round-reduced (7-round) AES that speeds up the previous best by 200-800x. The work, done with ETH Zurich, Tel Aviv University, and University of Haifa, accompanies the released CryptanalysisBench benchmark (arXiv:2607.18538), though Anthropic notes neither result affects production systems today.