HAWK has not been deployed anywhere, and Bitcoin does not use it. Still, it belongs to the broader push toward quantum-resistant cryptography—a challenge Bitcoin developers are actively racing to address.
This week, AI company Anthropic reported that its Claude Mythos Preview model discovered a flaw that effectively halves the key strength of HAWK. The system is a proposed replacement for today’s digital signature schemes, which secure online banking and web transactions.
The breakthrough required about 60 hours and roughly $100,000 in computing resources, targeting an algorithm that had already undergone two years of development and multiple rounds of expert review.
Digital signature schemes like HAWK verify that a message or dataset originates from the holder of a specific private key. Bitcoin depends on these signatures for every transaction, and they also underpin secure web connections, indicated by the padlock icon in browsers.
Current signature methods are expected to become vulnerable in the age of quantum computing, and HAWK is one of several candidates being evaluated as a replacement. However, it has not yet seen real-world deployment.
The findings do not affect Bitcoin or Ethereum today, as both rely on elliptic curve cryptography, which was not targeted in this research. In addition, HAWK is not among the systems Bitcoin plans to adopt.
Bitcoin’s BIP-360 proposal outlines a transition to quantum-resistant addresses using three algorithms already standardized by NIST. It includes multiple options to ensure fallback protection if any approach is compromised.
What has changed is the speed of classical cryptographic attacks. A related proposal, BIP-361, argues that the migration window is shrinking, citing improvements in attack efficiency of up to 20 times. Anthropic’s results support this trend, showing how AI can accelerate such progress.
For HAWK’s smallest configuration, the estimated effort to recover a key dropped from around 2^64 operations to 2^38. While larger keys remain difficult to attack, increasing key sizes would eliminate much of HAWK’s efficiency advantage.
Anthropic disclosed the issue to HAWK’s developers in June and coordinated its public release through NIST.
In a separate result, the researchers improved attacks on a weakened version of AES—the widely used encryption standard for protecting wallet files—by factors of 200 to 800.
Encouragingly, the model achieved only limited gains—under tenfold—against Poseidon, a hash function used in many zero-knowledge proof systems supporting rollups and privacy protocols.
Initially, Claude declined to attempt the AES challenge, calling it genuinely difficult. After a few prompts, however, it generated billions of tokens over three days and identified the improvement. Verifying the result then took two researchers nearly a month.
The timing is notable. This week, the privacy-focused network Zcash rolled out an upgrade introducing a new shielded pool designed to remain secure in a future with quantum computers.
The cryptographic systems meant to guide this transition are now being tested by AI tools that can operate faster than the humans who designed them.
