Time Running Out for Bitcoin to Counter Quantum Computing Threat

Not all aspects of bitcoin are vulnerable to quantum computers. The process of bitcoin mining, which utilizes a type of math known as hashing, is secure against quantum attacks. The blockchain ledger and the rule that new bitcoins can only be created through mining would remain intact in the event of a quantum attack, allowing blocks to continue being produced and the chain to keep running. However, ownership of bitcoins would be at risk. Bitcoin wallets rely on a different type of math that converts a private key into a public address. This math is easy to perform in one direction but virtually impossible in the other, which is what prevents unauthorized individuals from spending someone else's coins. A quantum algorithm known as Shor's algorithm can bypass this security measure. Google recently released a paper demonstrating that a quantum attack on bitcoin could be carried out with fewer resources than previously thought, and within a timeframe that competes with bitcoin's block times. This article explores the potential risks, the current state of bitcoin's security, and whether the network can coordinate a major security upgrade before quantum computers become powerful enough to launch an attack. Approximately 6.9 million bitcoins, or about one-third of all mined bitcoins, are stored in wallets with publicly visible keys, making them vulnerable to quantum attacks. This includes early bitcoins stored in older address formats that published public keys by default, as well as any wallet that has been spent from, as spending reveals the key for the remaining balance. Bitcoin's pseudonymous creator, Satoshi Nakamoto, holds around 1 million bitcoins that are also at risk. The 2021 Taproot upgrade inadvertently expanded the problem by making transactions more efficient and private, but also publishing the key protecting any remaining balance at an address after a transaction. While there are ongoing debates and proposals among bitcoin developers to address the quantum threat, nothing concrete has been implemented yet. Ethereum, a major competitor to bitcoin, has had a formal quantum-resistant program in place since 2018 and is actively working on migrating its security to quantum-resistant math. Bitcoin, on the other hand, lacks a unified strategy to address this issue, with different proposals and no broad support from core developers. The lack of a centralized authority and a governance process makes it challenging for bitcoin to coordinate a response to the quantum threat. The migration of the 6.9 million exposed coins requires decisions that the network has historically avoided, such as freezing old address formats or allowing exposed coins to move to new quantum-safe addresses. Every option presents a challenge to bitcoin's character and stability. The question remains whether a network built to resist coordinated change can coordinate the biggest security upgrade in its history before the threat becomes a reality.