Claude Mythos cuts the cost of breaking HAWK-256 from 2^64 to 2^38 operations
Anthropic's Claude Mythos Preview improved the best-known attack on HAWK — a third-round NIST post-quantum signature candidate — in 60 hours, cutting the expected cost of recovering a HAWK-256 key from 2^64 to 2^38 operations. A second finding makes attacks on 7-round AES 200 to 800 times faster, and neither result touches deployed systems. Restoring HAWK's security level requires doubling its key size, which removes much of what made it an attractive candidate — a frontier model has now moved a live NIST standardization process that survived two years of expert human review.
Source: anthropic.com ↗
Despite HAWK having survived two rounds of expert human review over a period of two years, Mythos was able to improve the best-known attack on it in just 60 hours of work—effectively cutting its key strength in half.
Why this matters
- → AI autonomously discovered mathematical flaws in a NIST standardization candidate after humans missed them for
- → Frontier models can now find weaknesses in algorithms themselves, not just implementation bugs.
- → Raises stakes for cryptographic vetting as AI systems become more capable at mathematical discovery.