Grayscale, a digital asset manager, has released a research note advocating for accelerated efforts to enhance public blockchains' resistance to quantum computing. The note emphasizes that although technical solutions to this issue already exist, the more substantial challenge lies in garnering consensus among decentralized communities to implement these solutions. This comes in the wake of Google Quantum AI's recent paper, which suggested that breaking Bitcoin's elliptic curve cryptography would require fewer than 500,000 physical qubits and could be executed in approximately nine minutes.
The paper's findings have sparked a wave of industry responses, with CoinDesk's analysis indicating that such an attack would give an attacker around a 41% chance of stealing funds before a Bitcoin transaction confirms. Grayscale's research highlights four key takeaways from Google's findings, including the potential for progress toward a cryptographically relevant quantum computer to occur in discrete jumps, rendering timelines unpredictable. Moreover, post-quantum cryptography is already mature and securing internet traffic and certain blockchain transactions, with quantum risk varying significantly across blockchains depending on their transaction models, consensus mechanisms, and block times. From a purely engineering standpoint, Bitcoin is argued to have lower quantum risk due to its UTXO model, proof-of-work consensus, lack of native smart contracts, and specific address types that are not quantum-vulnerable if not reused after spending.
However, the more pressing question revolves around the roughly 6.9 million BTC in wallets with publicly exposed keys on the blockchain, including an estimated 1 million believed to belong to Satoshi Nakamoto. Possible solutions, as framed by Grayscale, include burning these coins, taking no action, or deliberately slowing their release by limiting the spending rate from vulnerable addresses.
The Bitcoin community's history of contentious debates over protocol changes may pose a significant obstacle to reaching a consensus on this issue. In contrast, Ethereum faces a distinct set of challenges, with Google's paper identifying five separate attack vectors worth over $100 billion in combined exposure. The Ethereum Foundation has been actively staking, but has not publicly addressed quantum migration timelines, highlighting the complex and multifaceted nature of the quantum problem facing public blockchains.