In brief
Anthropic said its unreleased Claude Mythos Preview model found a previously unknown attack on HAWK, dropping the cost of stealing its smallest key from 2^64 operations to 2^38.
The model also sped up an attack on a 7-round version of AES by 200 to 800 times, beating a record cryptographers set in 2013.
Each result cost roughly $100,000 in API usage, and Anthropic staff spent several hundred hours verifying the AES work was real.
Anthropic today said an unreleased version of its most powerful AI model found two previously unknown attacks on cryptographic algorithms, one of them against a scheme currently competing to become a U.S. federal standard.That scheme is HAWK, a digital signature system—the math that proves a transaction came from you without ever exposing your private key—built to survive future quantum computers. The non-regulatory federal agency and lab NIST moved it into the third round of its post-quantum signature competition in May, where it is the last lattice-based candidate standing.Claude found a symmetry buried in HAWK's math that no human had thought to use. For the smallest configuration, the cost of recovering a secret key fell from 2^64 operations to 2^38, roughly 67 million times less work.Fixing it means roughly doubling HAWK's keys. "Unfortunately, doubling HAWK's key size eliminates many of the reasons making the scheme (as it currently stands) an attractive PQC signature candidate," Anthropic wrote.
