Quantum Computing and Bitcoin Security: Current Threat Assessment and Future Outlook

Recently, Google's Willow Quantum Computing has once again sparked discussions about the potential threat of quantum computing to the security of the Bitcoin network. Although Willow has indeed made significant progress in the field of quantum computing, Bitcoin users currently do not need to worry excessively.

The Bitcoin protocol consists mainly of two parts: a mining system based on hash functions and a transaction signing system based on elliptic curves. Theoretically, both parts could be affected by Quantum Computing, respectively through Grover's algorithm and Shor's algorithm. However, the current computing power of Willow is far from being sufficient to pose a threat to the Bitcoin network.

Experts estimate that to launch an effective attack on the Bitcoin hash and signature system within a reasonable timeframe, thousands of logical quantum bits are needed. Each logical quantum bit requires thousands of physical quantum bits to encode. This means that attacking the Bitcoin network may require millions of physical quantum bits, while Willow currently has only 105 physical quantum bits, far from the required scale.

Even if future quantum computers reach a computational power sufficient to impact the Bitcoin network, their influence on the mining system is relatively limited. Although Grover's algorithm can accelerate the computation process, it does not break the essence of the hash function, and a large amount of computation is still required to find a valid hash value. This situation is more like the emergence of a new type of efficient mining equipment in the market.

However, for certain types of Bitcoin addresses, especially the earliest P2PK and the latest P2TR addresses that are directly based on public keys, more attention is indeed needed. In contrast, hash-based address forms such as P2PKH, P2SH, P2WPKH, and P2WSH are relatively safer. However, reusing these addresses may also expose the public key, which can lead to potential risks.

To address the potential threat of Quantum Computing, Bitcoin developers have been exploring various solutions. In the future, technologies such as hash-based Lamport signatures or quantum-resistant lattice cryptography may be introduced, all of which can be implemented through a soft fork.

In addition to technological upgrades, good user habits are also key to effectively defending against quantum threats. For example, using a new receiving address for each transaction to avoid address reuse; transferring assets to more secure isolated witness addresses before quantum computing threats become a reality, etc.

It is worth noting that the development of quantum computers not only affects cryptocurrencies but will also have a profound impact on many important fields such as traditional financial systems, defense systems, and secure communications. Therefore, closely monitoring the progress of quantum computing technology is crucial for society as a whole.

In summary, the threat of Quantum Computing to cryptocurrencies like Bitcoin remains limited in the short term. However, it is still wise to maintain good usage habits and keep a close eye on the developments in Quantum Computing. As technology continues to advance, the cryptocurrency community will also continue to explore and develop more robust security measures to address potential challenges that may arise in the future.