Bitcoin Developers Consider Alternative Strategy to Counter Quantum Computing Threats

The Bitcoin community is exploring a new approach to addressing the potential risks posed by quantum computing, shifting from a proactive freeze of vulnerable coins to a reactive strategy that relies on the attacker's actions. A recent proposal by BitMEX Research introduces a 'canary' system, where a small amount of bitcoin is placed in a special address that can only be unlocked by a quantum-capable attacker, triggering a network-wide freeze of older wallets once the threat is demonstrated. This approach is designed to replace the controversial BIP-361 proposal, which would impose a fixed five-year timeline for phasing out vulnerable addresses. The new system includes a financial incentive, allowing users to contribute to a bounty that rewards the first entity to publicly demonstrate a quantum attack, rather than exploiting the vulnerability for personal gain. However, this strategy assumes that the attacker will prioritize claiming the bounty over maximizing profits through theft, which may not be a reliable assumption. The proposal also includes a 'safety window' to prevent stealth attacks, during which vulnerable coins can still be moved but the recipient will be unable to spend them for an extended period. If the canary is triggered during this window, the coins would be frozen retroactively, increasing the risk for any attacker attempting to quietly extract funds. While this approach reduces the risk of disrupting users prematurely, it relies on an uncertain bet that the first entity capable of breaking Bitcoin's security will choose to claim the bounty rather than execute a potentially catastrophic theft.