Time Runs Out for Bitcoin to Counter Quantum Threat, Putting 6.9 Million BTC at Risk

While not all aspects of bitcoin are vulnerable to quantum computers, the ownership of coins is at significant risk. Bitcoin mining, which utilizes hashing that quantum computers cannot break, would continue unaffected. However, the math protecting bitcoin wallets, which converts private keys into public addresses, is susceptible to quantum attacks. A quantum algorithm known as Shor's can bypass this security, potentially allowing an attacker to drain 6.9 million BTC, including those held by bitcoin's creator, Satoshi Nakamoto. The exposed pool of bitcoin includes early coins and any wallet that has been spent from, as spending reveals the public key. Bitcoin's pseudonymous creator holds roughly 1 million bitcoin, which has been untouched since the network's inception and is now at risk. The 2021 Taproot upgrade inadvertently expanded the problem by publishing keys for any bitcoin spent since its activation. To address this, proposals such as BIP-360 and a detection system from BitMEX Research have been put forth, but neither has gained broad support from core developers. The lack of a formal governance process and funding for engineering work hinders bitcoin's ability to migrate to quantum-resistant cryptography, unlike Ethereum, which has a dedicated program and teams working on the migration. The coordination problem stems from bitcoin's development culture, which treats central authority as a failure mode and emphasizes rare and hard protocol changes. This makes decisions on freezing old address formats, allowing exposed coins to move to new addresses, or setting a migration deadline challenging. The fate of Satoshi's coins is a prime example, as freezing old formats would protect them but make them inaccessible, including to Satoshi. The Google paper warns that a successful attack should not be seen as a wake-up call but rather as a potential signal that post-quantum cryptography adoption has already failed. This underscores the need for immediate action, with Ethereum's eight-year head start in quantum-resistant migration serving as a precedent.