Digital asset manager Grayscale has backed accelerated efforts to make public blockchains quantum-resistant in a new research note, saying the technical solutions already exist, but the toughest challenge is getting decentralized communities to agree on their implementation.
“Public blockchains do not have a CTO; they are global communities governed by consensus,” wrote Zach Pandl, head of research at Grayscale. “The potential threat of quantum to digital security therefore presents both a challenge and an opportunity.”
The memo follows a week of intensive industry response to Google’s Quantum AI paper, which revealed that breaking Bitcoin Elliptic curve cryptography would require fewer than 500,000 physical qubits, about 20 times fewer than previous estimates, and could be run in about nine minutes once the machine is bootstrapped.
CoinDesk’s analysis of the document found that the attack gives an attacker about a 41% chance of stealing funds before a Bitcoin transaction is confirmed.
Pandl highlighted four takeaways from the Google search that Grayscale found compelling. Progress toward a cryptographically relevant quantum computer can be made in “discrete jumps” rather than linear, making timelines unpredictable.
Technical solutions, notably post-quantum cryptography, are mature and already secure internet traffic and certain blockchain transactions. Quantum risk varies significantly across blockchains based on their transaction model, consensus mechanism, and block time.
From a purely technical perspective, Pandl argued that Bitcoin has lower quantum risk than other chains because it uses a UTXO model, proof-of-work consensus, no native smart contracts, and certain address types that are not quantum vulnerable if not reused after spending.
The tougher question is what to do about the roughly 6.9 million BTC stored in wallets where public keys are already permanently exposed on the blockchain, including around 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 “that means he’s still there, 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 the same way – 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, highlighting last year’s dispute around image data stored in blocks.
The contrast with Ethereum is worth noting.
CoinDesk reported last week that Google’s paper identified five distinct attack vectors against Ethereum worth more than $100 billion in combined exposure, covering account keys, admin keys on stablecoins, smart contract code, consensus mechanisms and data availability.
Justin Drake, a researcher at the Ethereum Foundation who co-authored the Google paper, estimated there was at least a 10% chance of recovering a quantum key by 2032. The foundation has been betting aggressively, investing $93 million of ether in validators in a single day last week, but has not publicly addressed quantum migration timelines.
