The HAWK system has not been deployed anywhere, and Bitcoin does not use it. However, it is part of the broader race to develop quantum-resistant cryptography that Bitcoin developers are actively preparing for.
Earlier this week, AI firm Anthropic announced that its Claude Mythos Preview model uncovered a vulnerability that effectively cuts the key strength of HAWK in half. HAWK is a proposed replacement for the digital signature schemes currently used to secure online banking and web payments.
The discovery took about 60 hours and roughly $100,000 in computing power, targeting an algorithm that had already undergone two years of development and multiple rounds of expert human review.
Digital signature schemes like HAWK ensure that a message or dataset comes from the holder of a specific digital key. Bitcoin relies on such signatures for every transaction, and they are also used by websites to enable secure connections, indicated by the padlock icon in browsers.
Current signature systems are expected to be vulnerable to future quantum computers, and HAWK is one of several candidates being evaluated as a replacement. However, it has not yet been deployed in practice.
The findings do not affect Bitcoin or Ethereum at present, as both use elliptic curve cryptography, which was not targeted. Additionally, HAWK is not among the schemes Bitcoin plans to adopt.
Bitcoin’s BIP-360 proposal outlines a shift to quantum-resistant addresses using three algorithms already standardized by NIST, with multiple options included to provide fallback protection if any are compromised.
What has changed is the speed of classical cryptographic attacks. A related proposal, BIP-361, warns that the transition window is shrinking, citing improvements in attack efficiency of up to 20 times. Anthropic’s results reinforce this trend, demonstrating how AI can accelerate such advances.
For HAWK’s smallest configuration, the estimated cost of recovering a key dropped from about 2^64 operations to 2^38. While larger keys remain secure, increasing key sizes would eliminate much of HAWK’s efficiency advantage.
Anthropic disclosed the vulnerability to HAWK’s developers in June and coordinated its release through NIST’s public channels.
In a separate finding, the team improved attacks on a weakened version of AES—the standard encryption used to secure wallet files—by factors ranging from 200 to 800.
Notably, the model achieved only modest improvements, under tenfold, against Poseidon, a hash function widely used in zero-knowledge proof systems that support rollups and privacy protocols.
Initially, Claude declined to work on the AES problem, describing it as genuinely difficult. After a few prompts, however, it generated billions of tokens over three days and identified the improvement. Verifying the result took two researchers nearly a month.
The timing is significant. This week, the privacy-focused network Zcash rolled out an upgrade introducing a new shielded pool designed to remain secure even in a quantum future.
The cryptographic systems intended to carry the industry through that transition are now being tested by AI tools that can operate faster than the humans who created them.
