Points of Focus

• Anthropic’s Claude Mythos broke the HAWK-256 post-quantum signature candidate in about 60 hours.
• Bitcoin is not vulnerable to the attack, but the result intensifies calls for post-quantum migration.
• The breakthrough highlights how AI could rapidly accelerate future cryptographic vulnerability research.

Anthropic’s unreleased Claude Mythos Preview model has reignited the cryptocurrency industry’s debate over Bitcoin’s long-term quantum security after uncovering a practical key recovery attack against HAWK 256, a post-quantum digital signature candidate under evaluation by the US National Institute of Standards and Technology (NIST).

The AI model completed the semi-autonomous research in 60 hours, exposing a mathematical flaw that had gone unnoticed by cryptographers for nearly two years.

New Anthropic research: Discovering cryptographic weaknesses with Claude.

Claude Mythos Preview has helped our researchers find weaknesses in cryptographic algorithms—the mathematical methods that are used to keep data private.

Read more: https://t.co/TYKLjb3Q7V

— Anthropic (@AnthropicAI) July 28, 2026

The breakthrough does not threaten Bitcoin directly because the network does not use HAWK. Instead, it demonstrates how advanced AI systems are beginning to accelerate cryptographic research, raising fresh questions about how quickly existing security assumptions could change.

The discovery comes as Bitcoin developers continue discussing how and when the network should migrate toward quantum-resistant cryptography.

AI breakthrough adds urgency to Bitcoin’s quantum roadmap

HAWK 256 was one of nine digital signature candidates selected by the NIST for its additional post-quantum standardization process. Anthropic said Claude Mythos identified a previously overlooked mathematical weakness involving a nontrivial automorphism in the underlying lattice structure, allowing a significantly faster key recovery attack after the issue had gone unnoticed by human researchers for nearly two years.

Although Bitcoin relies on the Elliptic Curve Digital Signature Algorithm rather than HAWK, the result has intensified concerns that AI could dramatically shorten the timeline for discovering weaknesses in modern cryptographic systems.

Earlier this year, Google researchers estimated that breaking RSA encryption with a fault-tolerant quantum computer may require around 1 million noisy qubits, substantially fewer than previous estimates, renewing discussions about the pace of quantum progress.

Vitalik Buterin has also repeatedly argued that Ethereum should prepare for quantum-resistant upgrades before the threat becomes immediate, advocating gradual migration rather than waiting until practical quantum computers arrive.

Bitcoin’s quantum migration debate continues

The latest development builds on months of discussion within the Bitcoin community over how to future-proof the network.

In July, Coinbase joined the newly formed Bitcoin Security Consortium alongside BlackRock, Fidelity Digital Assets, Block, Blockstream, and Strategy to coordinate research into post-quantum migration while supporting Bitcoin Improvement Proposal 360, which outlines possible approaches for upgrading Bitcoin’s cryptography.

Blockstream CEO Adam Back has consistently argued that Bitcoin has sufficient time to prepare, maintaining that quantum computers capable of threatening Bitcoin remain years away. However, he has also supported continued research into migration strategies so upgrades can be introduced gradually without disrupting the network.

LATEST: ⚡ Cryptographer and Blockstream CEO Adam Back says Bitcoin faces no meaningful quantum computing threat for at least 20-40 years, noting that post-quantum encryption standards can be implemented long before the technology arrives. pic.twitter.com/gjV1ULqwmJ

— CoinMarketCap (@CoinMarketCap) November 17, 2025

Strategy executive chairman Michael Saylor has similarly downplayed the likelihood of an immediate quantum threat while acknowledging that Bitcoin’s open source development model allows the protocol to evolve as new security requirements emerge. Both have stressed that preparation should begin well before any practical attack becomes feasible.

AI could transform cryptographic research

The HAWK result may ultimately have greater implications for cybersecurity than for cryptocurrencies alone.

Researchers have long warned that AI could significantly reduce the time required to discover mathematical weaknesses, audit complex codebases, and analyze cryptographic constructions. Rather than replacing human cryptographers, frontier AI models are increasingly acting as research assistants capable of testing thousands of hypotheses in parallel.

For Bitcoin and the wider blockchain industry, the finding reinforces a growing consensus that quantum readiness is no longer solely about advances in quantum computing. Rapid improvements in AI could also accelerate the discovery of vulnerabilities, making proactive cryptographic upgrades increasingly important.

While Bitcoin faces no immediate risk from the HAWK attack, the latest research strengthens the argument that post-quantum migration should be treated as a long-term engineering priority rather than a distant theoretical concern.