Show HN: Bitcoin and Quantum Computing – a three-part research series
20 hours ago
- #Post-Quantum Cryptography
- #Bitcoin Security
- #Quantum Computing
- Breaking Bitcoin's elliptic curve (secp256k1) with Shor's algorithm requires 1,200-2,300 logical qubits for minutes, but current quantum computers have only 48-94 logical qubits for milliseconds.
- Expert predictions on cryptographically relevant quantum computers range from 2029 to 'never', with skepticism due to fundamental physical barriers.
- Bitcoin does not use encryption; it uses digital signatures, so 'harvest now, decrypt later' does not apply to fund theft, only to privacy concerns.
- Quantum mining via Grover's algorithm is impractical, requiring unrealistic energy levels (3% of the Sun's output) and is vastly slower than ASIC miners.
- Approximately 30-35% of Bitcoin supply has exposed public keys, but 65-70% remains safe in unspent addresses with hidden public keys.
- Quantum computing industry faces financial incentives to promote fear, with over $40 billion in funding but low revenue and high stock sell-offs by executives.
- Vendor roadmaps have been revised backward, with missed targets and rebranding from 'quantum supremacy' to 'readiness', indicating slow progress.
- Over 17 researchers are actively developing post-quantum defenses for Bitcoin, with proposals like BIP-360, SHRINCS signatures, and Quantum Safe Bitcoin (QSB).
- BIP-360 is a soft-fork address format for post-quantum security, but it defers signature schemes; SHRINCS offers compact hash-based signatures with state management challenges.
- Taproot's script-path is post-quantum secure, but many users lack a usable script path; new solutions like zk-STARK proofs for BIP-32 wallets reduce vulnerabilities.
- QSB enables quantum-resistant transactions using existing Bitcoin consensus rules without a soft fork, though it's costly and limited to legacy scripts.
- Lightning Network lacks a post-quantum adaptor signature construction, posing a significant unsolved problem for scaling solutions.
- No immediate quantum threat exists to Bitcoin; recommendations include avoiding address reuse, securing xpubs, and planning for future protocol upgrades.