Anthropic's Mythos Finds Mathematical Weaknesses in Cryptographic Algorithms
Anthropic’s Frontier Red Team published a report showing that its AI model Mythos discovered a previously unknown symmetry in the mathematical lattice underpinning HAWK, a post-quantum digital signature candidate in NIST’s standardization process—reducing the effective key length by half and dropping the estimated attack cost from 2⁶⁴ to 2³⁸ operations in 60 hours. Mythos also found a novel Möbius bridge attack against a reduced-round variant of AES-128, accelerating the best known attack by up to 800x, and produced improvements against simplified versions of LEA, Serpent-128, Salsa20, Poseidon, and SHA-1. Each attack cost roughly $100,000 in API compute, and Anthropic has released demonstration code, the AES reasoning chain, and a joint CryptanalysisBench benchmark with ETH Zurich and other universities.