Coinbase’s global head of investment research has warned that advances in quantum computing represent a structural risk to Bitcoin’s (BTC) long-term security, with roughly one-third of the network’s circulating supply potentially vulnerable due to exposed public keys.
David Duong, Global Head of Investment Research at Coinbase, said that while the so-called “quantum threat” is not imminent, it is approaching faster than many investors previously assumed.
Duong noted that growing concern around quantum computing has already begun to surface in regulatory guidance and institutional disclosures, signaling that the issue is moving from theoretical to strategic.
Quantum Risk Shifts From Hypothetical To Structural
Duong said the primary danger would emerge at what researchers refer to as “Q-day,” when cryptographically relevant quantum computers become capable of running algorithms such as Shor’s and Grover’s at a scale sufficient to undermine existing cryptographic systems.
Bitcoin relies on two core cryptographic components: the Elliptic Curve Digital Signature Algorithm, which secures transaction signatures, and the SHA-256 hashing function, which underpins proof-of-work mining.
Quantum advances could challenge both, though Duong emphasized that the risk to transaction signatures is the more pressing concern.
According to Coinbase’s analysis, quantum mining that materially disrupts Bitcoin’s economic model remains a lower-priority threat due to scaling constraints.
By contrast, the potential to derive private keys from exposed public keys represents a more immediate structural vulnerability.
Roughly One-Third Of Bitcoin Supply Exposed
As of block height 900,000, Duong estimates that approximately 6.51 million Bitcoin, about 32.7% of total supply, could be vulnerable to long-range quantum attacks.
These risks stem largely from address reuse and legacy script types that reveal public keys directly onchain.
The vulnerable categories include Pay-to-Public-Key outputs, bare multisignature scripts, and Taproot addresses, with early-era coins often associated with Satoshi-era wallets forming a notable subset.
Once a public key is exposed onchain, a sufficiently powerful quantum computer could, in theory, derive the corresponding private key.
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Duong also highlighted a second class of risk: short-range attacks that could occur during the act of spending.
When a transaction enters the mempool and its public key becomes visible, all outputs temporarily face exposure, reinforcing the urgency of migrating to quantum-resistant signature schemes.
Institutional And Regulatory Signals Are Growing
Duong pointed to rising institutional awareness of the issue.
In May 2025, BlackRock flagged quantum computing as a potential long-term risk in amended disclosures for its iShares Bitcoin Trust ETF.
At the policy level, U.S. and European agencies have begun directing critical infrastructure providers to plan transitions to post-quantum cryptography by 2035.
While Bitcoin and other open blockchain protocols can theoretically upgrade their cryptography, Duong stressed that such a transition would require broad coordination across the ecosystem, including wallets, exchanges, miners, and custodians.
Preparing For A New Security Regime
Duong framed the challenge as one of preparation rather than panic.
He said the probability of a successful quantum attack in the near term remains low, but the scale of potential impact makes early planning essential.
“The urgency,” he wrote, “comes from the amount of value already locked into cryptographic assumptions that may not hold indefinitely.”
The analysis adds to a growing body of research suggesting that Bitcoin’s long-term resilience will depend not only on economics and decentralization, but also on its ability to adapt cryptographically as computing capabilities evolve.
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