The emergence of quantum computers poses a significant risk to Bitcoin's security, with the potential to compromise the cryptocurrency's core cryptography. According to recent research by Google, a sufficiently powerful quantum computer could crack Bitcoin's core cryptography in under nine minutes, which is faster than the average Bitcoin block settlement time. This has sparked concerns among developers, who are now considering various upgrades to build defenses against this potential threat.
Approximately 6.5 million bitcoin tokens, worth hundreds of billions of dollars, are vulnerable to a quantum computer attack, including coins belonging to Bitcoin's pseudonymous creator, Satoshi Nakamoto. The potential compromise would not only damage Bitcoin's core tenets of 'trust the code' and 'sound money' but also put the entire cryptocurrency at risk. To mitigate this threat, several proposals are under consideration, including BIP 360, which removes the public key permanently embedded on-chain, and SPHINCS+, a post-quantum signature scheme built on hash functions.
Other proposals, such as Tadge Dryja's Commit/reveal scheme and Hourglass V2, aim to protect transactions in the mempool and slow the spending of old coins, respectively. While these proposals are still in the development stage, they demonstrate the Bitcoin community's proactive approach to addressing the quantum computing threat and ensuring the long-term security of the cryptocurrency.