Citi Says Bitcoin Faces Greater Quantum Risk Than Ethereum Due to Governance
Citi analysts warned that faster quantum computing progress shortens the timeline for practical attacks on digital assets, with Bitcoin seen as more exposed than Ethereum. The bank cited Bitcoin's governance model, which would make a quantum-resistant upgrade slow and contested.
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Citi Flags Bitcoin's Structural Exposure
Citi analysts said in a research note that recent quantum computing breakthroughs have shortened the timeline for practical attacks on digital assets, and that Bitcoin faces an outsized share of that risk. CoinDesk reported the bank's view that the threat is compressing timelines for both crypto and broader internet infrastructure. Decrypt's account of the same note places the core issue in Bitcoin's design: public keys are exposed on the network from the moment a transaction is broadcast until it is confirmed, leaving a window in which a quantum attacker could in theory derive a private key and redirect funds.
The Qubit Estimates and Timeline Disagreement
The report cites Google research suggesting a machine with roughly 500,000 qubits could break current encryption in minutes. No such machine exists yet, and the analysts said the estimates are still improving. Decrypt reports that Google's own Q-Day estimate, the point at which a quantum computer capable of breaking current cryptography comes online, is 2032, while other researchers believe it could arrive as early as 2030. The two sources do not give a shared timeline, and the sources do not say whether Citi adopts either date.
Governance as the Binding Constraint
Decrypt's reporting frames the difference between Bitcoin and Ethereum as primarily political rather than technical. Moving Bitcoin to quantum-resistant cryptography would require broad network consensus, extensive testing, and likely a hard fork, a process the analysts described as notoriously difficult. Citi argued that Ethereum and other proof-of-stake networks are better positioned because of more flexible governance and a record of regular protocol upgrades. The analysts also said proof-of-stake networks are not immune: an attacker holding enough private keys could in theory control about 33% of staked assets and disrupt finality or network operations.
Dormant Supply and Proposed Upgrades
Decrypt estimates that 6.7 to 7 million BTC sit in wallets whose public keys are already exposed, and that roughly 1 million BTC attributed to Satoshi Nakamoto remain in early address formats that are particularly vulnerable. At current prices, Decrypt puts the value of that second group at about $82 billion. Citi pointed to BIP-360 and BIP-361 as proposed Bitcoin upgrades to watch for quantum readiness. Decrypt also reports that Fireblocks CEO Michael Shaulov, speaking at the Financial Times Digital Asset Summit the previous week, called Bitcoin's quantum challenge "mostly a coordination issue" rather than a technical one, a view consistent with Citi's emphasis on adaptability over current design.
Why It Matters
For Traders
Quantum headlines can pressure Bitcoin sentiment in the short run, but no sourced evidence here points to an imminent attack, so the near-term price effect is hard to isolate.
For Investors
Citi's report puts Bitcoin's governance speed, not just cryptography, on the table as a long-horizon risk factor to weigh against other networks.
For Builders
Wallets and tooling that expose public keys longer than necessary, and address formats that are vulnerable, should be reviewed against BIP-360 and BIP-361 as they develop.
This article is for information only and is not financial advice. Read the full disclaimer.
