Bitcoin (BTC) Quantum Exposure Reaches 6.9 Million Coins at Block 950,000

A Bitcoin (BTC) security analysis found that 6,900,573 BTC had publicly revealed keys at block 950,000, highlighting the scale of the network’s theoretical quantum exposure without equating it to likely losses.

The figure represented 34.45% of circulating supply. It measures whether the public key needed to spend a Bitcoin output is visible on-chain, rather than estimating how much BTC could be stolen in a quantum attack.

Active exposure among balances of at least 1 BTC totaled 3,331,639 BTC across 46,163 groups, equal to 48.28% of all exposed supply. Never-spent or inactive balances of at least 1 BTC totaled 3,413,767 BTC.

After identified operational entities were removed while coins attributed to Satoshi Nakamoto were retained, the dormant segment fell to 2,277,978 BTC across 73,658 groups and 1,096,018 unspent transaction outputs.

The large-balance figures below apply specifically to that dormant, non-entity segment:

Dormant, non-entity balance threshold Exposed BTC Groups UTXOs

At least 10 BTC 2,187,481 39,897 365,830

At least 100 BTC 351,654 675 33,573

The distribution means cryptographic exposure is not the same as practical theft risk. Active exchanges, custodians and other entities may be able to move funds to new addresses, while dormant, abandoned or lost holdings may be more difficult or impossible to migrate.

Under the analysis’s sizing model, moving all exposed BTC represented about 140.99 days of workload. The estimate dropped to 9.37 days for active balances of at least 1 BTC, 2.56 days for dormant non-entity holdings, 23.33 hours for balances of at least 10 BTC and 2.17 hours for balances of at least 100 BTC.

Those figures measure relative workload, not actual migration timelines. They exclude the effects of fees, coordination and user behavior.

Bitcoin output types expose keys differently. Early pay-to-public-key outputs reveal public keys by design. Hashed address types generally reveal them when funds are spent and the address is reused, while Taproot outputs are classified as exposed because their output keys are visible on-chain.

More than 34% of Bitcoin had revealed a public key on-chain as of March 1, 2026. BIP-361, a draft Bitcoin Improvement Proposal, outlines a staged migration away from legacy ECDSA and Schnorr signatures, beginning with restrictions on new payments to quantum-vulnerable addresses. The proposal has not become an activated Bitcoin rule.

Other measurements have produced different totals because they used different block heights and classification methods. Exposure was measured at 34.55% at block 951,000, while a later strict measurement counted 7,111,096 BTC, or about 35.4%, at block 969,805 on Oct. 4, 2026. Separate estimates in May and at block 959,193 were lower.

No quantum computer can currently carry out the proposed attack. No Bitcoin has been confirmed stolen through a quantum attack.

The practical challenge is migration: Users and custodians would need to move exposed funds before a sufficiently powerful quantum computer could derive private keys from publicly visible keys. TokenPost previously examined claims about the share of Bitcoin facing quantum risk.