The Quantum Threat to Bitcoin: How Your Cryptocurrency Could Be Stolen in Under 10 Minutes

To grasp how a quantum computer can be utilized to steal bitcoin, it's essential to understand the target - the encryption that secures bitcoin transactions. Bitcoin employs elliptic curve cryptography, which relies on a one-way function to prove ownership. Each wallet has a private key, a secret number, and a public key derived from it. The public key can be shared without compromising security, as reversing the function is virtually impossible for classical computers. However, quantum computers can exploit this one-way function using Shor's algorithm, which solves the discrete logarithm problem efficiently. Google's recent paper has reduced the estimated number of qubits required to break bitcoin's encryption, making the threat more tangible. The paper 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 reduces the time needed to derive a private key to approximately nine minutes, which is alarming given bitcoin's average block confirmation time of 10 minutes. The implications of this vulnerability and the potential consequences for bitcoin security are significant, with roughly one-third of the total bitcoin supply potentially at risk.