Bitcoin Developers Propose 'Wait and React' Strategy to Counter Quantum Computing Threats

The Bitcoin community is considering a novel approach to mitigating the risks associated with quantum computing: refraining from freezing vulnerable coins unless a quantum-capable attacker demonstrates their capabilities. However, this plan relies on the assumption that the attacker will prioritize claiming a bounty over exploiting the vulnerability for personal gain. The proposed 'canary' system involves placing a small amount of bitcoin in a special address that can only be accessed by a quantum-capable attacker, thereby providing public proof of the threat and triggering a network-wide freeze of older wallets. This approach is designed to provide an alternative to the controversial BIP-361 proposal, which would impose a fixed five-year timeline for phasing out vulnerable addresses. Critics of BIP-361 argue that it undermines Bitcoin's core principle of private key holder control, as it could result in the permanent freezing of unmigrated coins. The 'canary' system incorporates a financial incentive, allowing users to contribute to a bounty that rewards the first entity to demonstrate a quantum attack. Additionally, the proposal introduces a 'safety window' to make stealth attacks more difficult, during which vulnerable coins can still be transferred but the recipient will be unable to spend them for an extended period. While this approach reduces the risk of premature disruption to users, it rests on the assumption that the first entity capable of breaking Bitcoin's security would prioritize claiming the bounty over executing a potentially catastrophic theft. This assumption is at odds with Bitcoin's historical emphasis on preventing worst-case scenarios and its resistance to protocol-level interventions to undo harmful events.