Time is Running Out for Bitcoin to Counter Quantum Computing Threat

Not all aspects of bitcoin are vulnerable to quantum computer attacks. The process of adding new blocks to the blockchain, known as mining, relies on a type of mathematics called hashing that is resistant to quantum computing. The blockchain itself and the rule that new bitcoins can only be created through mining would survive a quantum attack, with blocks continuing to be produced and the chain remaining intact. However, ownership of bitcoins is at risk. Bitcoin wallets are protected by a different type of mathematics that converts a secret private key into a public address. This math works in one direction but not the other, preventing unauthorized access to coins. A quantum algorithm known as Shor's algorithm can potentially break this math, and a recent paper by Google indicated that such an attack could be launched with fewer resources than previously thought. This article explores the potential risks and responses to the quantum threat. Approximately 6.9 million bitcoins, or one-third of all mined coins, are stored in wallets whose public keys are visible on the blockchain, making them vulnerable to quantum attacks. This includes early bitcoins and any wallet that has been used for a transaction, as spending reveals the public key. The 2021 Taproot upgrade also expanded the problem by publishing the key protecting remaining coins at an address after a transaction. While there are debates and proposals among bitcoin developers, no concrete plan has emerged to address the quantum threat. In contrast, Ethereum has had a formal quantum-resistant program since 2018 and is working on migrating its security to new math that quantum computers cannot break. The lack of a centralized authority and governance process in bitcoin makes it harder to coordinate a response to the quantum threat. The migration of 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 has significant implications for the character of the bitcoin network. The window to respond to the quantum threat may be closing, and developers face the question of whether a decentralized network can coordinate a major security upgrade before it's too late.