Claude Discovers New Cryptographic Weaknesses in HAWK and Simplified AES

Anthropic announced a major breakthrough in cryptography by its Claude Mythos Preview model, which discovered previously unknown vulnerabilities in the post-quantum digital signature scheme HAWK and a simplified version of AES. The model ran continuously for about 60 hours, incurring API costs of approximately 100,000 USD.

Confirmed

• In collaboration with several universities, Anthropic introduced CryptanalysisBench to evaluate the cryptanalysis capabilities of large language models. The benchmark indicates that frontier models can break 65%–86% of Tier 1 cryptographic schemes.
• Claude Mythos Preview identified a stronger attack against HAWK, significantly undermining its security. HAWK had previously passed two years of expert review.
• The model discovered new attack methods against reduced-round AES, accelerating attack speeds by 200 to 800 times.
• Anthropic has published the related cryptography research papers, along with the model's chain-of-thought materials for AES.

Unconfirmed

• Rumors claiming "AI cracked post-quantum encryption" are exaggerated. Several users who relayed the findings (such as @ccerrato147 and @imjustnewatai) clarified that full AES encryption remains secure. Furthermore, the HAWK algorithm is not currently deployed in practice and remains resistant to attacks at larger parameter sizes. These discoveries do not pose an immediate threat to practical computing systems today.

Why It Matters

• This marks an evolution for AI, shifting from finding software code implementation bugs to identifying mathematical flaws within cryptographic algorithms themselves. Although currently confined to theoretical levels and simplified versions, it demonstrates the practical potential of large language models in complex code security and frontier vulnerability mining. Consequently, European AI teams are calling for a re-evaluation of the resilience of current cryptographic systems.

2026-07-29 ~ 2026-07-29 · 35 related posts

• Claude Exposes Novel Weaknesses in Cryptographic Algorithms — nordicinst · 2026-07-29
• [source] Anthropic says Claude found new weaknesses in HAWK and round-reduced AES — AnthropicAI · 2026-07-29
• [source] Anthropic’s new benchmark finds frontier LLMs can break 65%–86% of tier-1 ciphers — AnthropicAI · 2026-07-29
• [source] Anthropic posts the papers and chain-of-thought behind its crypto attacks — AnthropicAI · 2026-07-29
• Anthropic’s Claude Mythos reportedly found post-quantum crypto flaws humans missed — Polymarket · 2026-07-29
• Anthropic Shows Claude Can Discover Mathematical Flaws in Cryptographic Algorithms — moyix · 2026-07-29
• Mythos Preview found a new attack on HAWK after two years of review — Kyrannio · 2026-07-29
• Anthropic’s Claude Mythos AI reportedly finds new attacks on cryptographic algorithms — luisdans · 2026-07-29
• Anthropic's Mythos Preview Model Accelerates AES Attack Speed by 200-800x in One Week — tszzl · 2026-07-29
• Anthropic's Claude Halves Post-Quantum Security, Accelerates AES Attacks by 800x — petrusenko_max · 2026-07-29
• Anthropic says Claude Mythos Preview exposed structural weaknesses in HAWK cryptography — PsychologicalBox5208 · 2026-07-29
• Anthropic’s Claude found a missed structural weakness in HAWK after two years of review — ccerrato147 · 2026-07-29
• Claude AI Discovers Critical Flaw in Post-Quantum Security Candidate — Mazrael33 · 2026-07-29
• Curated Research on Post-Quantum HAWK and AES Cryptanalysis — imjustnewatai · 2026-07-29
• Anthropic researchers used Claude to find weaknesses in HAWK and weaker AES variants — muchcharles · 2026-07-29
• Anthropic says Claude helped uncover weaknesses in cryptographic algorithms — rickasaurus · 2026-07-29
• A one-line meme about Claude breaking AES lands after Anthropic’s crypto post — matthew_d_green · 2026-07-29
• Anthropic used Claude Mythos for 60 hours and found crypto flaws at a $100K cost — vista8 · 2026-07-29
• Anthropic says Claude found a faster attack on a reduced AES cipher, not real AES — nptacek · 2026-07-29
• Anthropic says Claude helped find cryptographic weaknesses, amid chain-of-thought debate — basedjensen · 2026-07-29
• Anthropic says Claude Mythos Preview helped find weaknesses in cryptographic algorithms — jedisct1 · 2026-07-29
• Claude Mythos Preview finds new cryptanalytic attacks on HAWK and AES — 新智元 · 2026-07-29
• Anthropic joke claims Claude Mythos found post-quantum crypto flaws — tanduyha · 2026-07-29
• Anthropic’s Claude shows strong cryptanalysis results on HAWK and AES — matthew_d_green · 2026-07-29
• Follow-up says HAWK is undeployed, non-transferable, and not just broken by AI — matthew_d_green · 2026-07-29
• Anthropic says Claude helped researchers find weaknesses in cryptographic algorithms — teortaxesTex · 2026-07-29
• Anthropic Hawk AES cryptanalysis thread draws strong praise — joshua_saxe · 2026-07-29
• Anthropic’s latest crypto attacks target HAWK and reduced-round AES, not deployed standards — matthew_d_green · 2026-07-29

7 near-duplicate retellings: jedisct1 · ccerrato147 · fkasummer · inductionheads · matthew_d_green · vista8 · Assix0098