The Quantum Threat to Bitcoin: How a 9-Minute Window Can Compromise Your Cryptocurrency

To understand how a quantum computer can be used to steal bitcoin, it's essential to grasp the basics of bitcoin's encryption and the weaknesses that a quantum algorithm can exploit. Bitcoin relies on elliptic curve cryptography, which uses a one-way map to derive a public key from a private key. This process is based on a mathematical operation performed on a specific curve, making it virtually impossible for classical computers to reverse the process and determine the private key. However, a quantum algorithm known as Shor's algorithm can efficiently solve the discrete logarithm problem, breaking the encryption and potentially allowing an attacker to access the bitcoin. The recent Google paper reduced the estimated number of qubits required to run Shor's algorithm, making the threat more plausible. The paper introduced a practical attack scenario, which involves precomputing parts of the algorithm and then waiting for a target public key to appear. This approach reduces the time required to derive a private key to approximately nine minutes, which is alarmingly close to the average block confirmation time of ten minutes. The potential vulnerability of 6.9 million bitcoin, which have already had their public keys exposed on the blockchain, is a significant concern. The next piece in this series will delve into the practical implications of this threat and the ongoing advancements in quantum computing hardware.