In a recent research note, Grayscale, a digital asset management firm, expressed support for expedited efforts to enhance public blockchains' resistance to quantum computing. The note emphasizes that technical solutions to this issue already exist but acknowledges the difficulty in reaching a consensus among decentralized communities to implement these solutions. This discussion follows a week of intense industry responses to a paper by Google Quantum AI, which revealed that compromising bitcoin's elliptic curve cryptography would require fewer than 500,000 physical qubits and could be accomplished in approximately nine minutes. The study found that such an attack would give an attacker around a 41% chance of stealing funds before a bitcoin transaction is confirmed.
Grayscale highlighted four key takeaways from the Google research, including the potential for progress toward a cryptographically relevant quantum computer to occur in sudden jumps, making timelines unpredictable. The firm also noted that post-quantum cryptography is already mature and in use for securing internet traffic and certain blockchain transactions, and that quantum risk varies significantly across different blockchains. From a purely engineering perspective, Grayscale argued that bitcoin has a lower quantum risk compared to other chains due to its 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 challenging question is how to address the approximately 6.9 million BTC in wallets with permanently exposed public keys on the blockchain, including an estimated 1 million coins believed to belong to Satoshi Nakamoto. Binance co-founder Changpeng Zhao recently raised this question, suggesting that if Satoshi's coins are moved during a migration, it could indicate that he is still active, and if they are not moved, it might be better 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. However, the firm notes that the bitcoin community has a history of contentious debates over protocol changes, which could hinder the decision-making process.
In contrast, Ethereum faces different challenges, with Google's paper identifying five attack vectors worth over $100 billion in combined exposure. Ethereum Foundation researcher Justin Drake estimated a 10% chance of quantum key recovery by 2032, and while the foundation has been actively staking ether, it has not publicly addressed quantum migration timelines.