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

Quantum computers are not just faster versions of classical computers, but a distinct type of machine that leverages the unique laws of physics at the atomic and particle level. Understanding how a quantum computer works is crucial to grasping how it can be used to steal Bitcoin by exploiting the cryptocurrency's security vulnerabilities. This piece delves into the specifics of Bitcoin's encryption, the weaknesses that a quantum computer can exploit, and the nine-minute window that a hacker has to break the encryption and steal the cryptocurrency. Bitcoin's security relies on elliptic curve cryptography, which involves a one-way mathematical function that makes it easy to generate a public key from a private key, but virtually impossible to reverse the process using a classical computer. However, a quantum algorithm known as Shor's algorithm can break this one-way function, allowing a hacker to derive the private key from the public key. This algorithm works by using the principles of superposition, entanglement, and interference to evaluate a function on multiple inputs simultaneously and filter out incorrect answers. The recent paper by Google's Quantum AI division has reduced the estimated number of qubits required to run Shor's algorithm against Bitcoin's elliptic curve from millions to fewer than 500,000, making the threat more imminent. The paper also introduced a practical attack scenario, where a hacker can precompute the first half of the calculation and then finish the second half in approximately nine minutes once a target public key appears. This timing gives the hacker a roughly 41% chance of submitting a competing transaction before the original transaction confirms. The bigger concern is the 6.9 million Bitcoin that are already vulnerable to an 'at-rest' attack, where a hacker can take as long as needed to derive the private key from the public key.