Claude AI Just Cracked a Post-Quantum Test Scheme and Found a Faster 7-Round AES Attack
Claude Mythos Preview successfully derived an end-to-end key-recovery attack against HAWK-256, a post-quantum signature scheme candidate in NIST's standardization process. The attack exploits a previously unused symmetry in the lattice structure of HAWK, reducing the security level from 2^64 to 2^38 for HAWK-256 and improving gate-count estimates for larger parameters. For AES-128, Mythos enabled a 200- to 800-fold speedup on a seven-round variant by removing a 256-way guessing step via a novel
Analysis
TL;DR
- Claude Mythos Preview successfully derived an end-to-end key-recovery attack against HAWK-256, a post-quantum signature scheme candidate in NIST's standardization process.
- The attack exploits a previously unused symmetry in the lattice structure of HAWK, reducing the security level from 2^64 to 2^38 for HAWK-256 and improving gate-count estimates for larger parameters.
- For AES-128, Mythos enabled a 200- to 800-fold speedup on a seven-round variant by removing a 256-way guessing step via a novel invariant fingerprint called the Möbius Bridge.
- Neither result affects production systems: HAWK-256 is a challenge parameter only, and the AES attack requires impractical numbers of chosen plaintexts.
- Anthropic released full technical papers, reproducibility artifacts, and code, with Mythos conducting most research autonomously under human oversight.
Why It Matters
This breakthrough demonstrates that advanced AI agents like Claude Mythos can independently discover non-trivial cryptographic vulnerabilities in standardized schemes, potentially accelerating cryptanalysis but also raising concerns about AI-assisted attacks on future standards. For practitioners, it underscores the need for rigorous, automated verification of cryptographic designs and highlights how AI may reshape both offensive and defensive capabilities in cybersecurity. Researchers should consider these findings when evaluating the long-term resilience of post-quantum candidates and symmetric ciphers under evolving analytical tools.
Technical Details
- HAWK-256 Attack: Exploits a hidden automorphism (symmetry) in the lattice underlying the HAWK signature scheme. Constructs a τ-cocycle lattice from the public key, applies lattice reduction and sieving to recover short vectors, then reconstructs a functionally equivalent signing basis (592-byte decoded key). Runtime estimated at ~3h 42m on a 96-core server; reduces work factor from 2^64 to 2^38 for HAWK-256. Gate counts improved for HAWK-512 (2^150 → 2^108) and HAWK-1024 (2^288 → 2^182), though these remain infeasible.
- Seven-Round AES-128 Attack: Modifies meet-in-the-middle attacks by introducing the "Möbius Bridge"—an invariant fingerprint unaffected by a 256-way enumeration step previously required. This eliminates redundant computations, yielding 200–800× speedup depending on metric. Requires ~2^105 chosen plaintexts, rendering it impractical for real-world use. Code includes C/Python/Rust components for validation but does not execute full end-to-end recovery on actual AES-128.
- AI Role: Mythos Preview operated autonomously over ~60 hours in a multi-agent setup, with humans providing only project direction, compute resources, and verification. API cost was ~$100,000. All results are reproducible via published artifacts.
- Scope Limitations: HAWK attack targets only HAWK-256 (challenge parameter); AES attack applies to reduced-round variants and remains computationally prohibitive at scale. No impact on full-round AES or other NIST signature candidates.
Industry Insight
Cryptographic standardization bodies like NIST must now incorporate AI-driven cryptanalysis into their evaluation frameworks, as autonomous agents can uncover subtle structural weaknesses invisible to traditional methods. Organizations adopting post-quantum algorithms should prioritize schemes with conservative security margins and undergo independent red-teaming using advanced AI tools before deployment. Meanwhile, developers of symmetric ciphers should design resistance against invariant-based optimizations early in the specification phase to preempt similar speedups in reduced-round analyses.
Disclaimer: The above content is generated by AI and is for reference only.