The Quantum Threat to Bitcoin: How Your Coins Can Be Stolen in Under 10 Minutes

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 uses a system called elliptic curve cryptography, which relies on a one-way map to prove ownership. This map is based on a mathematical operation that uses a private key to derive a public key. The security of this system relies on the difficulty of reversing the math, which is known as the elliptic curve discrete logarithm problem. However, a quantum algorithm called Shor's algorithm can efficiently solve this problem, potentially allowing an attacker to derive a private key from a public key. Google's recent paper has reduced the estimated number of qubits required to run Shor's algorithm, making it more feasible to build a quantum computer capable of breaking bitcoin's encryption. The paper also introduced a practical attack scenario, which involves precomputing parts of the algorithm and waiting for a target public key to appear. This attack scenario has significant implications for bitcoin's security, particularly for the 6.9 million coins that are already exposed on the blockchain.