Bitcoin Magazine's latest print edition, The Quantum Issue, features a quantitative brief on Bitcoin's exposure to quantum computing attacks, built on a snapshot of the Bitcoin Quantum Exposure Dashboard at block 950,000. The subject carries weight for Bitcoin because the network's current signatures rely on elliptic-curve cryptography (ECDSA and Schnorr), which a sufficiently capable quantum computer running Shor algorithm could in theory break — so the dashboard tracks the precondition for such attacks: public keys that have become visible on-chain. The analysis decomposes the headline exposure figure into distinct segments and assesses which portions represent the most persistent practical risk. The full piece appears in The Quantum Issue, shared online as an early look at the ideas explored throughout the print edition.

Headline Figure Overstates Practical Theft Risk

The raw dashboard view shows 6,900,573 BTC exposed. The brief stresses that this figure intentionally treats exposure as a cryptographic condition: a public key has appeared on-chain. That is described as the right starting point, but it is not the same as economic loss risk. A live exchange wallet, an institutional multisig, a dormant early address, and an abandoned key can all be cryptographically exposed while having very different abilities to migrate.

Active and Known-Entity Exposure Is Less Concerning Than Raw Exposure Implies

The active ≥1 BTC filter captures 3,331,639 BTC, 48.28% of all exposed supply — a large amount of bitcoin, but one concentrated in 46,163 groups rather than millions of unmanaged holders.

The largest visible active exposures include operational entities such as exchanges, brokers, custodial multisig operators, stablecoin infrastructure, and mining-related wallets. These entities are among the most likely to monitor quantum developments, coordinate wallet rotations, and migrate before a practical attack window opens.

The brief notes that this does not make the exposure irrelevant: it creates coordination and execution risk. It is, however, meaningfully different from lost-key risk. Active custodial and exchange balances are generally the coins most likely to move first in a credible threat scenario.

Dormant and Non-Responsive Exposure Is the Core Long-Term Problem

When active entities are removed and the view is narrowed to never-spent or inactive balances of at least 1 BTC, exposed supply stands at 3,413,767 BTC. After removing known operational entities while retaining Satoshi-attributed coins, the remaining exposed supply falls to 2,277,978 BTC across 73,658 groups and 1,096,018 UTXOs.

That 2.28 million BTC segment is described as the cleanest approximation in the dataset of the harder-to-mitigate exposure surface: early holders, inactive self-custody, old address reuse, dormant P2PK outputs, and coins that may be lost or otherwise unable to respond. This is where the practical quantum risk is most persistent, according to the analysis.

Script type underpins much of that persistence. Pay-to-public-key (P2PK) outputs, common in Bitcoin's earliest era, place the full public key on-chain by design, whereas pay-to-public-key-hash (P2PKH) conceals it behind a hash until the address's first spend — and reusing a P2PKH address produces the same reveal. Dormant P2PK outputs therefore carry visible keys from the moment of creation, which is why they figure prominently in the hardest-to-migrate part of the dataset.

Quantum Attack Economics Shrink the Target Set Further

A capable quantum adversary would still face operating costs, limited throughput, opportunity costs, transaction fees, and operational risk. The rational target set is therefore unlikely to include every exposed key and is more likely to begin with the highest-value exposed balances.

Applying balance thresholds shows how quickly the practical attack surface compresses. With known entities removed and only dormant or never-spent balances included, the ≥10 BTC view still contains 2,187,481 BTC, but only 39,897 groups and 365,830 UTXOs. At the ≥100 BTC threshold, the target set drops to 351,654 BTC across just 675 groups and 33,573 UTXOs.

Script-Type and Threshold Observations

The script-type breakdown is filtered to show only never-spent and inactive balances, with known operational entities removed and Satoshi coins retained unless excluded by the balance threshold. The publication cautions that displayed totals may differ by a few BTC from KPI totals due to dashboard rounding at the script-type level.

The brief also flags an important threshold note: the apparent crossover from P2PK dominance at the ≥10 BTC threshold to P2PKH dominance at the ≥100 BTC threshold should not be read as P2PK risk disappearing. It is primarily a filter artifact. The Satoshi-attributed P2PK outputs in the dataset hold 50 BTC per key, so they are included at the ≥10 BTC threshold and excluded once the pubkey balance threshold exceeds 50 BTC. That exclusion causes the P2PK bucket to collapse from roughly 1.716 million BTC to about 10,000 BTC in the ≥100 BTC view.

Caveats and Source

The brief emphasizes that migration estimates are useful for relative sizing, not as forecasts of real-world coordination, fee pressure, or user behavior. Against that backdrop, the dashboard's block-height snapshots offer a concrete way to follow the issue over time: later readings can show whether custodial balances rotate and how the dormant share of exposed supply shifts. On the protocol side, adding quantum-resistant signature types has been a recurring topic of discussion among Bitcoin developers, though deploying one would require a consensus change to the network.

The data comes from the Bitcoin Quantum Exposure Dashboard snapshot at block 950,000, and the analysis assumes a dashboard methodology PDF supplied separately to the editor.

The article first appeared on Bitcoin Magazine and was written by Wicked.