- About 6.04 million Bitcoins, worth 30% of the supply, already have public keys visible on chain.
- Exchange custody varies widely, with Binance 85% exposed while Coinbase sits at just 5%.
- Citi also warns that quantum computing threat timelines are shrinking faster than expected.
A new analysis from Glassnode has quietly revealed something the crypto industry has been avoiding: 6.04 million Bitcoin, representing 30.2% of all issued supply, already has its public key visible on-chain. In simple terms, that means a sufficiently powerful quantum computer would not need to wait for those coins to move. It could target them right now.
Citi has added its own warning, flagging that quantum computing timelines are compressing faster than previously estimated, with breakthroughs in qubit stability and error correction bringing the threat closer than a decade-old defense plan anticipated.
How Bitcoin Becomes Exposed
Bitcoin’s quantum vulnerability comes in two forms:
Structural exposure (1.92 million BTC, 9.6% of supply)
- Early Satoshi-era coins where the public key is visible by design
- Legacy bare multisig outputs
- Modern Taproot outputs where the key is exposed on-chain by default
- Many of these coins may be lost or inactive and cannot be moved to safer addresses
Operational exposure (4.12 million BTC, 20.6% of supply)
- Coins that were initially protected but became exposed through address reuse
- Every time a Bitcoin address spends and still holds a balance, the public key becomes visible
- Exchange-related balances account for 1.63 million BTC of this exposure alone
The Exchange Problem
The data reveals a striking disparity in how exchanges handle custody security:
- Coinbase: only 5% of labeled balances are quantum-exposed
- Binance: approximately 85% exposed
- Bitfinex: 100% exposed
- Robinhood and WisdomTree: 100% exposed
- US, UK, and El Salvador sovereign treasuries: 0% exposed
Governments have maintained near-perfect quantum safety for years. Exchanges have drifted from 55% safe in 2018 to 45% safe today.
The Governance Problem Nobody Has Solved
Unlike other blockchains, Bitcoin has no central authority to mandate an upgrade. The XRP Ledger has already mapped a post-quantum readiness path targeting 2028. Bitcoin would require unprecedented consensus across miners, nodes, exchanges, and wallet providers to change its signature algorithm.
Citi’s warning is that the window between a feasible upgrade and a potentially catastrophic event is shrinking. When major banks start formally pricing quantum risk, insurers and institutional custodians follow.
The coins are already exposed. The clock is already running.
Related: Ripple Partners with Project Eleven to Quantum-Proof the XRP Ledger
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