In a recent research note, Grayscale, a digital asset manager, emphasized the need for public blockchains to become quantum-resistant, citing the existence of technical solutions but highlighting the difficulty in achieving consensus among decentralized communities to implement these solutions. This follows a recent industry response to a paper by Google Quantum AI, which found that breaking Bitcoin's elliptic curve cryptography could be achieved with fewer than 500,000 physical qubits, potentially in under nine minutes.
The paper's findings have significant implications, including a roughly 41% chance of stealing funds before a Bitcoin transaction is confirmed. Grayscale identified four key takeaways from the Google research, including the potential for progress toward a quantum computer to occur in unpredictable, discrete jumps. The company also noted that post-quantum cryptography is already mature and securing certain internet traffic and blockchain transactions. However, the varied quantum risk across different blockchains, depending on their transaction models and consensus mechanisms, poses a challenge.
From a technical standpoint, Bitcoin's use of a UTXO model, proof-of-work consensus, and lack of native smart contracts reduces its quantum risk. Nevertheless, the question of what to do with the approximately 6.9 million BTC in wallets with permanently exposed public keys on the blockchain, including those believed to belong to Satoshi Nakamoto, remains a significant issue.
Possible solutions include burning these coins, taking no action, or limiting their release rate. However, Grayscale notes that the Bitcoin community has a history of contentious debates over protocol changes, which could hinder the implementation of a solution. In contrast, Ethereum faces distinct challenges, with five identified attack vectors worth over $100 billion in combined exposure. The Ethereum Foundation has been actively staking ether into validators but has not publicly addressed quantum migration timelines.