A report by Google's Quantum AI team has sparked concern among bitcoin users, stating that a future quantum computer could derive a bitcoin private key from a public key in approximately nine minutes. This has raised questions about the practical implications of such a scenario. To understand the issue, it's essential to grasp how bitcoin transactions work. When a user sends bitcoin, their wallet uses a private key to sign the transaction, which is then linked to a public key.
This public key is broadcast to the network and is visible to all. The connection between the private and public keys is based on a complex mathematical problem that classical computers cannot solve in a reasonable timeframe. However, a powerful quantum computer could potentially solve this problem, posing a significant risk to bitcoin security. The study found that a quantum computer could be pre-programmed to attack the system, and once a public key is visible, it would take around nine minutes to derive the private key.
This means that if a user's public key is exposed, an attacker with a quantum computer could potentially steal their funds. The issue is more pressing for the approximately 6.9 million bitcoin that are already at risk due to exposed public keys.
These coins are vulnerable to attack without the need for the nine-minute time frame, as the public keys are already visible. The bitcoin network's security is based on the assumption that private keys cannot be derived from public keys. If this assumption is compromised, the entire security model of the network is at risk. The solution to this problem is to implement post-quantum cryptography, which would replace the current vulnerable math with algorithms that are resistant to quantum computer attacks.
While Ethereum has been working on this migration for eight years, bitcoin has yet to start the process.