Google’s latest quantum computing breakthrough has raised fresh concerns about the future security of Bitcoin (BTC), particularly older holdings linked to Satoshi Nakamoto. The development comes as blockchain organizations and Coinbase prepare for potential threats to cryptocurrency wallets.
Google reported on October 15 that its Willow quantum chip reduced errors by approximately 40 times during specialized calculations. The research, published in Science, marks progress toward more reliable quantum computers, although current machines cannot break Bitcoin’s cryptography.
Google researchers demonstrated a process called ‘magic state cultivation,’ which prepares special quantum states needed for advanced calculations. These states help quantum computers perform operations that conventional machines cannot efficiently complete.
The Willow processor achieved 99.99% accuracy in states that passed testing. However, only about 8% of preparation attempts succeeded, showing that the technology still faces limitations. Researchers must improve the process before using it in larger quantum computers.
The 40-fold improvement concerns error reduction rather than the cost of attacking Bitcoin. Google acknowledged that researchers still need to demonstrate the method at a larger scale.
A sufficiently powerful quantum computer could eventually use Shor’s algorithm to recover private keys from exposed public keys. Such an attack would allow unauthorized Bitcoin transactions.
Bitcoin’s earliest wallets face particular exposure because some older addresses reveal public keys directly on the blockchain. These keys remain visible even when the coins have not moved for years.
Estimates suggest that approximately 6.4 million BTC could face future quantum attacks. This includes an estimated 1.1 million BTC associated with Bitcoin creator Satoshi Nakamoto, although ownership of those holdings has not been conclusively established.
Research into Bitcoin wallets exposed to quantum threats identifies older address formats and reused addresses as major areas of concern. Modern address formats can hide public keys until spending, although some newer formats expose them earlier.
Meanwhile, Glassnode's assessment of Bitcoin quantum exposure identified 1.92 million BTC in structurally exposed addresses and another 4.12 million BTC facing exposure through wallet practices. These estimates describe potential vulnerabilities rather than coins currently accessible to attackers.
The Quantum Alliance announced its formation on October 15, bringing together nine blockchain organizations to develop common security standards.
Members include Quantus, American Fortress, Intmax, Keystone, Midnight Foundation, Postquant Labs, Abelian, The Vault, and Hacken. Their work covers wallet protection, blockchain upgrades, privacy systems, and compatibility between networks.
The alliance’s Quantum Doom Clock identifies March 2028 as an early possible window for quantum computers capable of threatening existing cryptography. However, this remains a model-based estimate, not a confirmed deadline.
Coinbase outlined similar concerns on October 13, warning that Bitcoin’s transition to quantum-resistant security could take several years.
The exchange supported phased upgrades and identified BIP-360 and P2TRv2 as possible technical approaches. Its recommendations follow ongoing efforts to protect Bitcoin from quantum attacks. However, dormant and inaccessible wallets remain difficult to protect. Owners must possess valid keys to transfer their holdings into upgraded wallets.
Coinbase described coins that ‘cannot or will not move’ as ‘a separate governance and engineering problem,’ leaving developers to consider how future security rules should treat these holdings.
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