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

To understand how a quantum computer can steal bitcoin, it's essential to know how bitcoin's security works. Bitcoin uses a system called elliptic curve cryptography, which relies on a one-way mathematical function to prove ownership of coins. This function, known as the elliptic curve discrete logarithm problem, is virtually impossible for classical computers to solve, but a quantum algorithm called Shor's algorithm can solve it efficiently. Shor's algorithm uses the principles of superposition, entanglement, and interference to find the period of a function, which is equivalent to finding the private key that controls the coins. A 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, making the threat more realistic. The paper also introduced a practical attack scenario, where a quantum computer can precompute the first half of the calculation and then finish the second half in approximately nine minutes, giving it a 41% chance of succeeding before a transaction is confirmed. This has significant implications for the security of bitcoin, particularly for the 6.9 million coins that have already been exposed on the blockchain.