Expert analysis: Anthropic Mythos cryptanalysis (Matthew Green, JHU)

July 29, 2026 — Independent cryptographer analysis.

HAWK: not deployed; proposed PQC signature; attack halves security bits (still exponential); could fix by doubling keys but hurts efficiency rationale; challenge instance recoverable in hours; ingredients not exotic — thorough application of known tools. Does not transfer to Falcon.

AES: 7-round reduced variant only; modest constant-factor improvement over 2013 work; requires 2^89 cipher ops and 2^105 chosen plaintexts — not practical. Full 10-round AES unaffected.

Implication: verifiability is the bottleneck; HAWK-type runnable attacks easy to check; on-paper AES speedups harder. Timing is fortunate mid-PQC transition.