Quantum Computers Could Steal Bitcoin in 9 Minutes

Summary

• Alex Pruden agrees there is at least a 10% chance quantum computers will recover ECDSA private keys from exposed public keys by 2032, with personal bets for 2035.
• Google researchers identify an "on spent attack" where quantum computers can steal Bitcoin in 9 minutes by intercepting unspent transactions in the mempool.
• Bitcoin's slow block times (~10 minutes) make it especially vulnerable to real-time quantum attacks; faster block times (e.g., Ethereum's 12 seconds) provide accidental defense.
• Once quantum attacks are feasible, permissionless migration to post-quantum secure addresses becomes impossible, potentially trapping funds in vulnerable addresses.
• Prediction markets could theoretically hedge this quantum risk, but practical liquidity issues limit their effectiveness.
• There is controversy over burning coins with exposed public keys, with disagreements on community consensus and feasibility, highlighting governance challenges.
• Grover's algorithm for hashing is not a near-term threat due to astronomical qubit requirements, unlike Shor's algorithm for ECDSA.
• The quantum threat primarily targets Bitcoin and similar forks with slow parameters, not all blockchains equally, emphasizing protocol-specific vulnerabilities.
• The discussion underscores a significant long-term security risk for Bitcoin, with implications for asset valuation and network usability in a post-quantum era.