Glassnode
Glassnode's latest research maps Bitcoin's at-rest quantum exposure and finds that 6.04 million BTC — roughly 30.2% of issued supply — already has its public key visible on-chain, leaving the remaining 13.99M BTC (69.8%) shielded behind a hash until first spend. The figure is consistent with independent work from Google Quantum AI published in March 2026.
Why it matters
The exposed supply splits into two analytically distinct buckets. Structural exposure — outputs whose script type reveals the public key by design, including legacy P2PK, bare multisig, and modern Taproot (P2TR) — accounts for 1.92M BTC, or 9.6% of issued supply. The Satoshi and Satoshi-era cohort sits inside this bucket and is effectively immobile: if the keys are lost, those coins cannot voluntarily migrate to a safer script. Taproot is the modern nuance, structurally exposed today but addressable through BIP-360's proposed Pay-to-Merkle-Root (P2MR) output, which preserves Taproot's script-tree flexibility while removing the quantum-vulnerable key-path spend.
The larger and more actionable bucket is operational exposure: 4.12M BTC, or 20.6% of supply, where the public key was hidden initially but revealed through address reuse, partial spending, or custody practice. That figure is 2.1x the structural bucket, which reframes the quantum question: most of the visible risk on Bitcoin is a key-management problem, not a protocol-design problem.
Market impact
Entity-level data shows the exposure is not evenly distributed. Exchange-related balances account for 1.66M BTC, or roughly 40% of all operationally unsafe supply and 8.3% of all issued BTC. Among major venues, Coinbase shows only 5% of labeled balances in the exposed set, while Binance and Bitfinex sit at 85% and 100% respectively. Grayscale is near 50%, Fidelity and CashApp near 2%, and Robinhood and WisdomTree at 100%. Sovereign treasuries — the US, UK, and El Salvador — register 0% exposure. Government holdings have stayed above 99% operationally safe for years, while exchange-held BTC has drifted from roughly 55% safe in 2018 to about 45% today.
The framing matters for the market. The research is explicit that this is a baseline map of where public keys are already visible, not a forecast of quantum timelines or an estimate of exploit probability.
Source: [Measuring Bitcoin's Quantum-Exposed Supply — Glassnode Research – Digital Asset Market Intelligence](https://insights.glassnode.com/measuring-bitcoins-quantum-exposed-supply/)
Frequently asked questions
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What does 'quantum-exposed' Bitcoin mean in this framework?
A coin is quantum-exposed if the public key needed to spend it is already visible on-chain. Under that lens, a Cryptographically Relevant Quantum Computer running Shor's algorithm could in principle recover the private key without waiting for the owner to move the coin.
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How much of Bitcoin's issued supply is currently quantum-exposed?
Glassnode classifies 6.04M BTC — roughly 30.2% of issued supply — as quantum-exposed at rest. The remaining 13.99M BTC (69.8%) keeps the public key hidden behind a hash until the first spend.
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What is the difference between structural and operational quantum exposure?
Structural exposure (1.92M BTC, 9.6%) comes from script types that reveal the public key by design, such as legacy P2PK, bare multisig, and modern Taproot. Operational exposure (4.12M BTC, 20.6%) comes from coins that were initially protected but had their public key revealed through address reuse, partial spending,…
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Which exchanges and custodians show the highest share of exposed balances?
Among major venues, Bitfinex shows 100% of labeled balances in the exposed set, Binance 85%, and Robinhood and WisdomTree also 100%. Grayscale sits near 50%, while Coinbase is at 5% and Fidelity and CashApp near 2%. Sovereign treasuries — the US, UK, and El Salvador — register 0% exposure.
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Can operational quantum exposure actually be reduced?
Yes, and that is the central operational point of the report. Standard wallet-hygiene practices — avoiding address reuse, rotating change outputs, and improving custody key management — can shrink the operationally exposed set. Glassnode notes that government-held BTC has stayed above 99% operationally safe for years,…
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