Roughly 6.04 million BTC, about 30.2% of Bitcoin’s total issued supply, sits exposed to potential quantum computing attacks because the public keys tied to those coins are already visible on the blockchain. That’s the finding from on-chain analytics firm Glassnode, which also noted that the remaining 13.99 million BTC, or 69.8%, has no public-key exposure at rest.
In English: if quantum computers ever get powerful enough to crack Bitcoin’s cryptography, almost a third of all Bitcoin in existence would be the low-hanging fruit.
Why public-key visibility matters
Bitcoin’s security model relies on a one-way mathematical relationship between private keys and public keys. Your private key generates your public key, and your public key generates your address. The trick is that going backward, from public key to private key, is computationally impossible for today’s machines.
Quantum computers threaten to change that equation. Using an algorithm known as Shor’s algorithm, a sufficiently powerful quantum computer could theoretically reverse-engineer a private key from a known public key. The operative word is “known.” If your public key has never appeared on-chain, a quantum attacker has nothing to work with. If it has, you’re in the exposed category.
