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

The first part of this series delved into the principles of quantum computing, but understanding how it works is only half the story. To comprehend the threat it poses to bitcoin, we must examine the cryptocurrency's security mechanisms and where they are susceptible to quantum attacks. This piece will explore bitcoin's encryption, the role of elliptic curve cryptography, and how a quantum algorithm can exploit its weaknesses. Bitcoin's security relies on a one-way function, where a private key is used to generate a public key, but not the other way around. However, a quantum algorithm known as Shor's algorithm can potentially break this one-way function, allowing an attacker to derive the private key from the public key. This algorithm utilizes the principles of superposition, entanglement, and interference to efficiently solve the discrete logarithm problem, which is the foundation of bitcoin's security. Although Shor's algorithm has been known for over 30 years, its implementation has been hindered by the requirement for a large number of stable qubits. Recent research by Google has reduced the estimated number of qubits needed to launch a successful attack, making the threat more imminent. The study introduced a practical attack scenario, where a quantum computer can precompute parts of the algorithm and then finish the calculation in approximately nine minutes once a target public key is exposed. This timeframe is alarming, as it is comparable to bitcoin's average block confirmation time, giving an attacker a significant chance of succeeding. The vulnerability is not limited to newly exposed public keys but also applies to the approximately 6.9 million bitcoin that have already been exposed on the blockchain. As quantum technology continues to advance, the gap between the required hardware and the potential threat to bitcoin is closing rapidly.