USDBitcoin Faces Uneven Quantum Risk, Glassnode and Citi Warn
Latest estimates show exposed supply, governance hurdles and institutional gaps
TL;DR
- Glassnode estimated that 9.6% of Bitcoin supply is structurally exposed to quantum risk.
- Citi said Bitcoin faces greater coordination challenges than Ethereum in moving to quantum-resistant cryptography.
- Entity and exchange exposure varies sharply across custodians, issuers and trading platforms.
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Bitcoin’s quantum-computing risk is concentrated in specific exposed output types and key-management practices, with Glassnode estimating that 9.6% of total BTC supply, equal to about 1.92 million BTC, is structurally exposed, while Citi warned that Bitcoin may be harder than Ethereum to upgrade quickly because of its conservative governance model.
Glassnode described Bitcoin’s quantum-risk profile as a supply-segmentation issue, not a uniform network failure. The structurally exposed category includes early Satoshi-era Pay-to-Public-Key outputs, legacy Pay-to-Multisig structures and modern Pay-to-Taproot outputs, because those designs reveal public keys or public-key equivalents that a future quantum attacker would need to target.
Glassnode’s newer breakdown supersedes the broader earlier estimate that 6.7 million to 7 million BTC sit in wallets with already exposed public keys. The updated framework separates structural exposure, operational exposure and safe supply, rather than treating all public-key exposure as one risk bucket.
Citi Flags Bitcoin Governance as a Security Constraint
Citi warned that quantum-computing progress has shortened the expected timeline for practical attacks on digital assets. The estimates cited place a cryptographically meaningful quantum breakthrough in the 2030–2032 window, with Google’s referenced Q-Day estimate pointing to 2032 and other researchers cited by Citi suggesting the risk could arrive as early as 2030.
The exposure becomes theft-relevant only if quantum computers can break Bitcoin’s elliptic curve cryptography. ARK Invest’s March white paper said that would require about 2,330 logical qubits and tens of millions to billions of quantum gates.
Citi said Bitcoin faces greater risk than Ethereum because Bitcoin’s conservative governance model makes a rapid move to quantum-resistant cryptography harder to coordinate, test and activate. A Bitcoin migration would likely require broad network consensus, extensive testing and potentially a hard fork.
Ethereum and other proof-of-stake networks were described as better positioned because they have more flexible governance and a record of regular protocol upgrades. Citi still warned that proof-of-stake systems remain vulnerable if enough private keys are compromised, including a scenario where an attacker controls around 33% of staked assets and disrupts block finality or broader network operations.
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Upgrade Proposals and Holder Exposure
Citi identified adaptability as a key long-term resilience factor and flagged BIP-360 and BIP-361 as Bitcoin upgrade proposals to watch. Glassnode said BIP-360’s proposed Pay-to-Merkle-Root output type would create a quantum-proof path by removing Taproot’s quantum-vulnerable key-path spend, although the proposal does not itself add post-quantum digital signatures.
ARK Invest warned that “Choosing how to implement PQC” and deciding what to do about already vulnerable coins should remain separate questions. The warning reflects concern that disputes over vulnerable coins could cloud the technical discussion around deployment.
Glassnode said part of the structurally exposed supply “could be reduced if wallet infrastructure, address standards, and user behavior evolve.” It recommended that exchanges and custodians reduce key reuse, improve address hygiene and prepare migration into quantum-proof formats before a practical quantum breakthrough turns theoretical exposure into live security risk.
Fireblocks CEO Michael Shaulov described Bitcoin’s quantum challenge as “mostly a coordination issue,” aligning with Citi’s warning that governance friction may become as important as cryptography if quantum risk moves from theoretical to practical.
FAQ
What share of Bitcoin supply is structurally exposed?
Glassnode estimated the structurally exposed share at 9.6%.
Why did Citi say Bitcoin faces greater risk than Ethereum?
Citi pointed to Bitcoin’s conservative governance and harder upgrade coordination.
What is BIP-360 meant to address?
Glassnode said it would remove Taproot’s quantum-vulnerable key-path spend.
What did Fireblocks CEO Michael Shaulov say?
He called Bitcoin’s quantum challenge “mostly a coordination issue.”
This article has been refined and enhanced by ChatGPT.
