The notion that a future quantum computer could derive a bitcoin private key from its corresponding public key in approximately 9 minutes, as reported by Google's Quantum AI team, has sent ripples through the crypto community. To understand the practical implications, it's essential to grasp how bitcoin transactions work. When a bitcoin transaction is initiated, the sender's wallet uses a private key to sign the transaction, which is then broadcast to the network, revealing the associated public key. This public key is linked to the private key through a complex mathematical problem known as the elliptic curve discrete logarithm problem, which classical computers cannot solve efficiently.
However, a sufficiently powerful quantum computer utilizing Shor's algorithm could potentially reverse this math. The '9-minute' aspect comes into play when a quantum computer is 'primed' by pre-computing parts of the attack that are not dependent on a specific public key. Once a public key appears in the mempool, the quantum computer would only need about 9 minutes to derive the private key, potentially allowing an attacker to redirect funds before the original transaction is confirmed.
This 'mempool attack' is concerning but requires a quantum computer that does not yet exist. A more immediate concern is the approximately 6.9 million bitcoin that are already in wallets with permanently exposed public keys, making them more susceptible to quantum attacks without the need for the 9-minute race. The solution to this vulnerability lies in post-quantum cryptography, which involves replacing the current math with algorithms that are resistant to quantum computer attacks. While Ethereum has been working towards this migration, bitcoin has yet to initiate the process.