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

The Bitcoin community is considering a novel approach to mitigate the potential risks posed by quantum computing, which could potentially compromise the security of the network's digital signature schemes. Rather than imposing a pre-scheduled freeze on vulnerable coins, the proposed 'canary' system would only trigger a network-wide restriction if a quantum-capable attacker demonstrates their capabilities on-chain. This approach is designed to replace earlier plans, such as BIP-361, which would phase out vulnerable addresses over several years, potentially leaving unmigrated coins permanently frozen. The canary system works by placing a small amount of bitcoin into a special address that can only be unlocked by a quantum-capable attacker, serving as public proof that the threat has arrived and automatically triggering a network-wide freeze. To incentivize the first entity to demonstrate a quantum attack, users can contribute to a bounty, which rewards the attacker for revealing their capabilities rather than exploiting them for personal gain. However, this approach rests on the assumption that the first entity capable of breaking Bitcoin's security would claim the bounty rather than executing a potentially catastrophic theft. If this assumption proves incorrect, Bitcoin may face the worst of both worlds: the catastrophe it was trying to prevent, and the realization that a fixed-timeline defense would have stopped it. The proposal also introduces a 'safety window' to make stealth attacks harder, allowing vulnerable coins to move but preventing the recipient from spending them for an extended period, potentially around a year, and increasing the risk to any attacker attempting to quietly extract funds.