The concept of a quantum computer 'cracking' bitcoin in a matter of minutes has garnered significant attention, but the reality is more complex. When a bitcoin transaction is made, the sender's wallet uses a private key to sign the transaction, while also revealing the associated public key.
This public key is then broadcast to the network, where it waits to be confirmed by a miner. The link between the private and public keys is based on a mathematical problem known as the elliptic curve discrete logarithm problem, which classical computers are unable to solve in a practical timeframe. However, a sufficiently powerful quantum computer could potentially solve this problem, compromising the security of the bitcoin network.
The recent study found that a quantum computer could be 'primed' in advance, allowing it to derive a private key from a public key in approximately nine minutes. This timeframe is significant because it gives the attacker a roughly 41% chance of stealing the funds before the original transaction is confirmed. The main concern is not the nine-minute timeframe, but rather the fact that approximately 6.9 million bitcoins are already vulnerable to quantum attacks due to exposed public keys. These coins are at risk of being stolen without the need for the nine-minute race, as an attacker with a sufficiently powerful quantum computer could crack them at leisure.
The solution to this problem lies in post-quantum cryptography, which would replace the vulnerable math with algorithms that quantum computers cannot crack. While Ethereum has been working towards this migration for eight years, bitcoin has yet to start.