Digital asset manager Grayscale backed accelerated efforts to make public blockchains quantum-resistant in a new research note arguing that technical solutions already exist, but the tougher challenge is getting decentralized communities to agree to implement them.
“Public blockchains do not have CTOs; they are global communities governed by consensus,” wrote Zach Pandl, head of research at Grayscale. “Therefore, the potential threat to digital security from quantum technology presents both a challenge and an opportunity.”
The note follows a week of intensive industry response to Google’s Quantum AI paper, which found that breaking bitcoin Elliptic curve cryptography would require fewer than 500,000 physical qubits, about a 20-fold reduction from previous estimates, and could be executed in about nine minutes once the machine is ready.
Analysis of the document by CoinDesk found that the attack gives an attacker an approximate 41% chance of stealing funds before a bitcoin transaction is confirmed.
Pandl highlighted four conclusions from Google’s research that Grayscale found compelling. Progress toward a cryptographically relevant quantum computer can occur in “discrete leaps” rather than linearly, making timelines unpredictable.
Technical solutions, specifically post-quantum cryptography, are mature and already secure Internet traffic and certain blockchain transactions. Quantum risk varies significantly between blockchains depending on their transaction model, consensus mechanism, and block time.
From a purely engineering point of view, Pandl argued that bitcoin is lower quantum risk than other chains because it uses a UTXO model, proof-of-work consensus, no native smart contracts, and certain types of addresses that are not quantum vulnerable if not reused after spending.
The tougher question is what to do with the roughly 6.9 million BTC held in wallets where public keys are already permanently exposed on the blockchain, including roughly 1 million believed to belong to pseudonymous creator Satoshi Nakamoto.
Binance co-founder Changpeng Zhao raised the same question last week, saying that if Satoshi coins move during a migration “it means it’s still around, which is interesting to know,” and that if they don’t move “it might be better to effectively lock or burn those addresses.”
Grayscale frames the options similarly: burn them, do nothing, or deliberately slow their release by limiting the spending rate of vulnerable addresses, but noted that the bitcoin community has a history of contentious debates over protocol changes, pointing to last year’s dispute over image data stored in blocks.
The contrast with Ethereum is worth noting.
CoinDesk reported last week that the Google document identified five separate attack vectors against Ethereum worth more than $100 billion in combined exposure, spanning account keys, stablecoin management keys, smart contract code, consensus mechanisms, and data availability.
Ethereum Foundation researcher Justin Drake, a co-author of the Google paper, estimated at least a 10% chance of recovery of the quantum key by 2032. The foundation has been betting aggressively, investing $93 million in ether into validators in a single day last week, but has not publicly addressed quantum migration timelines.
