Bitcoin Worth Nearly $500B Vulnerable to Quantum Computing: Glassnode

Bitcoin Vulnerable to Quantum Computing Threat

Nearly one-third of all Bitcoin in circulation, representing over 6 million coins and valued at over $469 billion at the time of writing, is potentially vulnerable to theft if powerful quantum computers become a reality, according to a report published Wednesday by blockchain analytics firm Glassnode.

The analysis examined the Bitcoin blockchain to identify coins with exposed public cryptographic keys. It found that 6.04 million BTC, or 30.2% of the total supply, is susceptible to quantum risk, while the remaining 13.99 million BTC shows no public-key exposure. This estimate of exposed coins is lower than some previous figures, which have been closer to 7 million BTC.

The concern stems from the architecture of Bitcoin’s security. Each coin is controlled by a private key, which corresponds to a public key visible on the blockchain under specific circumstances. The potential threat is that a sufficiently advanced quantum computer, using an algorithm known as Shor’s algorithm, could theoretically recover a private key from a known public key.

In such a scenario, any coin whose public key has already been revealed on-chain would be immediately vulnerable, requiring no transaction to be initiated.

Categories of Exposure

Glassnode divides the exposed supply into two categories. Structural exposure accounts for 1.92 million BTC, or 9.6% of the issued supply. These coins are locked in script formats that inherently reveal the public key, including early “pay-to-public-key” outputs associated with Bitcoin’s pseudonymous founder, Satoshi Nakamoto, legacy multisignature structures, and more recent Taproot outputs. Many of these coins may be effectively unrecoverable, such as those in lost wallets or dormant holdings that cannot be moved to safer address formats.

The larger and more actionable category is what Glassnode terms operational exposure. This category totals 4.12 million BTC, or 20.6% of the issued supply. These coins were not initially vulnerable but became so through address reuse, a practice where a wallet receives multiple transactions at the same address, eventually broadcasting the public key during a spend and leaving any remaining balance exposed.

Exchange Vulnerabilities

Exchanges are significantly represented in this category. Within the operationally unsafe category, 1.66 million BTC, or 8.3% of the total supply, is exchange-related, accounting for approximately 40% of all operationally unsafe Bitcoin. The exposure varies significantly across platforms. Among the largest exchanges, Coinbase’s labeled balances appear largely concentrated in non-exposed structures, with only 5% exposed, while Binance and Bitfinex show comparatively high susceptible balances—85% and 100%, respectively.

Glassnode emphasized that its findings should not be interpreted as a risk ranking or a signal of solvency for any particular firm, stressing that the data reflects custody design choices rather than imminent danger. Sovereign Bitcoin holdings fared considerably better, with the United States, United Kingdom, and El Salvador all showing zero quantum exposure.

Mitigation Strategies and Future Developments

The report does not predict when, or if, a quantum computer capable of cracking Bitcoin’s encryption will exist. Instead, it presents its analysis as a baseline, noting that for exchanges and custodians, address hygiene, reserve management, reduced key reuse, and migration planning are practical measures to reduce visible exposure.

These findings come as quantum computing advances globally and as the Bitcoin developer community discusses protocol-level responses, including a proposed update known as BIP-360, which would introduce more quantum-resistant transaction formats. Another official proposal suggests freezing coins that are not migrated by a set deadline.

Estimates for “Q-Day”—when a quantum computer becomes powerful enough to crack the cryptography securing blockchains like Bitcoin and Ethereum—range from 2030 to 2032 and beyond. On Thursday, the United States government announced that it will invest over $2 billion in quantum startups and planned foundries to fuel American industry.