The Quantum Threat to Bitcoin: How a Powerful Computer Can Steal Your Cryptocurrency in Under 10 Minutes

To understand how a quantum computer can be used to steal bitcoin, we need to understand the basics of bitcoin's security. Bitcoin uses a system called elliptic curve cryptography, which relies on a one-way mathematical function to secure transactions. This function, known as the elliptic curve discrete logarithm problem, is virtually impossible for classical computers to solve. However, a quantum algorithm known as Shor's algorithm can solve this problem efficiently, potentially allowing a bad actor to derive a private key from a public key and steal bitcoin. A recent paper by Google reduced the estimated number of qubits required to run Shor's algorithm against bitcoin's elliptic curve, making the threat more realistic. The paper introduced a practical attack scenario that changes how to think about the threat, including a 'nine-minute window' during which a quantum attacker could derive a private key and submit a competing transaction. This has significant implications for the security of the bitcoin network, particularly for the 6.9 million bitcoin that are already exposed and vulnerable to an 'at-rest' attack.