# Operational Exposure Accounts for Most of Bitcoin’s Measured Quantum Exposure

By Simon Yoon

Canonical URL: https://www.tokenpost.com/news/technology/37837
Published: 2026-10-22T12:25:29.000Z
Updated: 2026-10-22T12:25:29.000Z
Section: Technology

> The estimate classifies 6.04 million Bitcoin (BTC), or 30.2% of issued supply, as exposed while at rest. Operational practices account for 4.12 million BTC of that total.

An estimated 6.04 million Bitcoin (BTC) are exposed to a potential quantum attack while at rest, with address use and custody practices accounting for the larger share. The operational category contains 4.12 million BTC, more than twice the 1.92 million BTC classified as structurally exposed.

The measure checks whether a public key tied to coins is already visible on the Bitcoin blockchain. By that measure, the exposed group represents 30.2% of issued supply. Another 13.99 million BTC, or 69.8%, have no public-key exposure while at rest under this test. That classification does not mean those holdings are protected from every future attack scenario.

In theory, a quantum computer with sufficient capacity could use Shor’s algorithm to derive a private key from a known public key. The tally does not estimate when such a machine might be able to carry out an attack. It also tracks existing exposure while coins remain unspent, separately from a public key becoming visible during a transaction.

The structural category covers output formats that reveal a public key or equivalent information by design. These include early P2PK outputs, bare multisig and Taproot. Taproot is counted because its output key is visible on-chain; that classification addresses key visibility alone and does not rate the protocol’s overall design.

A proposed BIP-360 P2MR output is intended to remove the vulnerable key path while preserving functionality similar to Taproot. It would not move existing Taproot holdings automatically, and it would not provide a complete post-quantum solution.

Operational exposure occurs when a key that was initially hidden becomes public through spending, address reuse or custody practices, while coins remain associated with it. That category totals 4.12 million BTC, or 20.6% of issued supply. Exchange-related balances account for about 1.6 million BTC, roughly 40% of the operational total. About half of labeled exchange-held BTC was classified as exposed, compared with less than 30% of non-exchange BTC. The tally measures public-key visibility, not custodians’ security or ability to repay customers.

Avoiding address reuse and promptly moving change assets can reduce operational exposure. Those practices do not change the structural category, which depends on the output format or a protocol-level change.