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

Understanding the inner workings of quantum computers is crucial, but it's equally important to grasp what they can attack and how they can be utilized to steal bitcoin. The security of bitcoin relies on a system called elliptic curve cryptography, which involves a private key and a public key derived from it through a mathematical operation. The relationship between the private and public keys is a one-way function, making it virtually impossible for classical computers to reverse-engineer the private key from the public key. However, a quantum algorithm known as Shor's algorithm can efficiently solve this problem, potentially allowing an attacker to derive the private key and gain control over the associated bitcoin. 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, making the threat more tangible. The paper also introduced a practical attack scenario, where parts of the calculation can be precomputed, leaving only the final step to be completed once a target public key is identified. This has significant implications for the security of bitcoin, particularly for the 6.9 million coins that have already had their public keys exposed on the blockchain.