New Attacks on HAWK and AES Cryptographic Schemes

Anthropic researchers report recovering signing keys for HAWK-256, one parameter set of HAWK, a lattice signature scheme that is a candidate in NIST's post-quantum signature competition. Their paper uses a mathematical symmetry of the key to reduce key recovery to a shortest-vector problem in about half the original dimension. Recovering an equivalent signing key allows signatures to be forged.

The experiment recovered keys for two generated public keys, with a recovery taking a few hours on a single 96-core server. For larger configurations the paper gives cost estimates under a gate-count model, lowering HAWK-512 from 2^150 to at most 2^108 gates; the authors say they have not attempted HAWK-512. The result therefore combines a demonstrated HAWK-256 attack with a revised estimate for larger parameters.