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Bitcoin BTC

Rank #1 by market capNo quantum-safe path live
Market cap
$1.54T
▲ 1.36% 24h
DeFi TVL
$4.1B
DefiLlama
Exposed share of supply
30.2%
Estimate, 2026-05-20
Value in exposed keys
$464B
share times market cap
Signature scheme
secp256k1 ECDSA and Schnorr
Key hidden until first signature
Partly

P2PKH and P2WPKH outputs pay to a hash of the public key, so the key is only revealed when the output is spent; if the address is never reused the key is exposed only while the spend is unconfirmed. P2PK outputs (early mining rewards) and Taproot P2TR outputs commit to the public key itself, so the key is visible from the moment funds arrive. Address reuse re-exposes a hashed address once it has spent.

Quantum-safe path
None live

Not live. BIP-360 (Pay-to-Merkle-Root, P2MR) is a Draft proposal, merged into the BIP repository in February 2026 (version 0.12.1 dated 2026-07-24), for a SegWit v2 output type like Taproot with the quantum-vulnerable key-path spend removed; it needs a soft fork and is not deployed. Post-quantum signature schemes themselves are deferred to a future companion BIP. Chaincode Labs (May 2025) proposed a dual-track migration; Galaxy launched a Bitcoin Quantum Readiness Initiative in 2026.

Where the exposure number comes from

Glassnode Research: Measuring Bitcoin's Quantum-Exposed Supply, as of 2026-05-20. At-rest measurement of BTC whose public key is already visible on chain: 1.92M BTC (9.6%) in output types that reveal the key by design (P2PK, P2TR) plus 4.12M BTC (20.6%) exposed through address reuse, partial spends or custody behaviour, for 6.04M BTC or 30.2% of issued supply.

Other studies bracket the same figure. Deloitte (page undated, written after Google's 2019 supremacy claim) counted about 2M BTC in P2PK plus about 2.5M BTC in reused P2PKH, over 4M BTC or about 25% of supply. Chaincode Labs (May 2025, Milton and Shikhelman) gives a 20 to 50% range (4 to 10M BTC) and cites Project Eleven's 6.26M BTC (about 30%) across about 11.1M addresses with a non-zero balance and an exposed key. Project Eleven's Bitcoin Risq List was reported at about 6.9M BTC in May 2026 (Crypto Briefing, 2026-05-09); the live page renders client-side and its current number could not be read here. Quantum Horizon (arXiv 2606.14484, June 2026) puts exposure at about 6M BTC (about 30%), of which about 2.3M BTC (12%) is dormant or lost and cannot be migrated.

Sources