Presidio Bitcoin estimates 6.5M BTC at quantum risk, urges address rotation
Presidio Bitcoin published a technical report on quantum risk to the Bitcoin network. It estimates up to 6.5 million BTC could be vulnerable if a cryptographically relevant quantum computer existed today and proposes a soft-fork path to post-quantum signatures source.
Headline
Presidio Bitcoin: 6.5M BTC exposed to quantum risk; soft-fork path proposed
The group frames the issue simply. Bitcoin is software. Cryptography is its strength and its weakness report.
If a CRQC can run Shor’s algorithm, it could derive private keys from exposed public keys. Theft would target coins with revealed pubkeys, not those still hidden behind hashes report.
Key exposures
- 6.5 million BTC at immediate risk today if a CRQC existed, roughly one-third of supply report.
- ~4.5 million BTC of that comes from address reuse, concentrated among a small set of large custodians. This portion is reducible by rotating to fresh addresses, without a protocol change report.
- 1.72 million BTC sits in legacy pay-to-pubkey (P2PK) outputs. Most are presumed lost report.
- Never-spent outputs that only reveal a pubkey hash are not vulnerable at rest under current understanding report.
Coordination is the hard part. Decentralization makes upgrades slower and riskier to coordinate across devs, users, wallets, custodians, and infrastructure. Move too early, and you may create new attack surfaces. Post-quantum schemes carry real trade-offs the ecosystem must accept report.
Timing is uncertain. Expert surveys cited put the chance of CRQCs arriving by 2030–2035 at about 50% report.
Path forward
- Deploy post-quantum signature schemes via soft fork, not a disruptive hard fork report.
- Activation is the key milestone. The report, referencing Chaincode’s playbook, places activation around months 6–7 if not earlier, followed by migration report.
Takeaway for investors
- Quantum risk concentrates in address-reused holdings and legacy P2PK outputs. Most exposure from reuse is mitigable without changing the protocol. The structural plan relies on a soft-fork PQ signature upgrade, with coordination as the main bottleneck report.
