Bitcoin Security Patched Against Quantum Threat, Legitimate Owners Risk Lockout
Key Summary
Bitcoin's quantum security is bolstered with a conditional sweep test, but legitimate owners risk being locked out if they don't migrate their coins before a potential quantum attack. The scenario assumes a future quantum machine can break Bitcoin's key cryptography, and early pay-to-public-key outputs reveal keys directly, making it possible for an attacker to authorize spending.
Bitcoin's Quantum Debate Extends Beyond Safer Signatures
Bitcoin's quantum debate extends beyond safer signatures: a conditional 10-block sweep tests how dormant coins could move and which owners could recover them.
The Stakes Are High
Crypto investor Nic Carter's worst-case quantum scenario consists of a hostile actor recovering the keys to dormant Bitcoin, then broadcasting a wave of spends across 10 blocks.
The Quantum Threat
A sufficiently powerful quantum computer could use Shor's algorithm to recover private keys from exposed public keys, gaining the ability to authorize spending.
The Impact on Bitcoin's Price
The stakes extend beyond choosing stronger cryptography. Glassnode's May 20 analysis identified 6.04 million BTC, or 30.2% of then-issued supply, with public keys already exposed.
Potential Solutions
Draft BIP-360 proposes Pay-to-Merkle-Root, a new output type without Taproot's exposed key spending path.
The Road Ahead
One potential rescue relies on a parent secret in a wallet that uses hardened key derivation.
Regulatory Uncertainty Remains
The impact on Bitcoin's price is still uncertain, and regulatory uncertainty remains a major concern.