Bitcoin Faces Looming Quantum Threat, Putting 6.9 Million Coins at Risk

While not all aspects of Bitcoin are vulnerable to quantum attacks, the ownership of coins is at significant risk. Bitcoin mining, which uses a type of math called hashing, is secure against quantum computers. However, the math that protects Bitcoin wallets, turning a private key into a public address, is a different story. A quantum algorithm known as Shor's can potentially break this math, allowing attackers to access and spend coins. Approximately 6.9 million Bitcoin, including those held by the cryptocurrency's pseudonymous creator Satoshi Nakamoto, are at risk due to exposed public keys. The recent Taproot upgrade has also expanded the problem by publishing the key protecting remaining coins at an address after a transaction. To address this issue, Bitcoin developers have proposed various solutions, including new quantum-safe address types and a detection system to trigger defensive actions in case of a quantum attack. However, these proposals lack broad support, and the network's governance structure, which treats central authority as a failure mode, makes coordination and implementation of effective solutions challenging. In contrast, Ethereum has a formal quantum-resistant program and a more structured governance process, which has allowed it to make significant progress in addressing the quantum threat. Bitcoin's ability to coordinate a massive security upgrade to prevent a quantum attack remains uncertain, with the timeline for such an attack potentially shorter than expected.