In a newly released research paper, Grayscale, a digital asset management firm, has expressed support for expedited efforts to enhance the quantum resistance of public blockchains. The paper posits that although the technical solutions to this challenge already exist, the more significant obstacle stems from the difficulty in achieving consensus among decentralized communities to implement these solutions. This comes on the heels of a recent paper by Google Quantum AI, which suggested that breaking Bitcoin's elliptic curve cryptography could be achieved with fewer than 500,000 physical qubits, a significant reduction from previous estimates, and could potentially be executed in under nine minutes.
The implications of this discovery have sparked a wave of responses across the industry. An analysis by CoinDesk revealed that such an attack could provide an attacker with a roughly 41% chance of stealing funds before a Bitcoin transaction is confirmed.
The research note from Grayscale highlights four key takeaways from the Google study that they find compelling. Firstly, progress toward developing a cryptographically relevant quantum computer may occur in sudden leaps rather than in a linear fashion, making it challenging to predict timelines. Secondly, the technical solutions, particularly post-quantum cryptography, are already mature and are being used to secure internet traffic and certain blockchain transactions.
Thirdly, the quantum risk varies significantly across different blockchains, depending on their transaction models, consensus mechanisms, and block times. Lastly, from a purely engineering perspective, Bitcoin is argued to have a lower quantum risk compared to other chains due to its use of a UTXO model, proof-of-work consensus, lack of native smart contracts, and specific address types that are not vulnerable to quantum attacks if not reused after spending. However, the more complex question revolves around the management of the approximately 6.9 million BTC held in wallets with publicly exposed keys on the blockchain, including an estimated 1 million believed to belong to Bitcoin's creator, Satoshi Nakamoto.
This issue was also raised by Binance co-founder Changpeng Zhao, who suggested that if Satoshi's coins were to move during a migration, it could indicate that Satoshi is still active, and if they do not move, it might be preferable to lock or effectively burn those addresses. Grayscale presents similar options - burning the coins, taking no action, or deliberately slowing their release by limiting the spending rate from vulnerable addresses. Nonetheless, the firm notes that the Bitcoin community has a history of contentious debates over protocol changes, as seen in the dispute over image data stored in blocks last year. In contrast, Ethereum faces a different set of challenges.
A report by CoinDesk highlighted that Google's paper identified five attack vectors against Ethereum, worth over $100 billion in combined exposure, including account keys, admin keys on stablecoins, smart contract code, consensus mechanisms, and data availability. Ethereum Foundation researcher Justin Drake, a co-author of the Google paper, estimated a minimum 10% chance of quantum key recovery by 2032. While the Ethereum Foundation has been actively staking, placing $93 million of ether into validators in a single day, it has not publicly addressed timelines for quantum migration.