The Impact of Quantum Computers on Bitcoin: No Need for Excessive Worry Currently

Will Quantum Computers Deal a Fatal Blow to Bitcoin? This topic always sparks widespread discussion and concern periodically. Recently, Google's Willow Quantum Processor has once again drawn people's attention. After research, we have come to the following conclusions:

• Willow has indeed made significant progress.
• But currently, Bitcoin users do not need to worry excessively.

The Bitcoin protocol can be simplified into two core parts: hash-based mining and elliptic curve transaction signatures. Both parts could theoretically be affected by Quantum Computing, respectively through Grover's algorithm and Shor's algorithm.

However, Willow's "computing power" is currently far from sufficient to have a substantial impact on these two parts. To attack Bitcoin's hashing and signing systems within a reasonable timeframe, it requires about a few thousand logical qubits. Depending on different processes, it may take thousands of physical qubits to encode into 1 logical qubit.

This means that attacking the Bitcoin network may require millions of physical quantum bits. However, Willow only has 105 physical quantum bits, so there is still a long way to go before it poses an actual threat.

What would happen if one day the computing power of Quantum Computers threatened the Bitcoin network? The impact on mining would be relatively limited. Grover's algorithm only accelerates the calculation process and does not break the essential laws of hashing; it still requires a large amount of computation to find the desired hash value. This can be understood as the emergence of a new type of efficient mining device in the market.

In terms of address signing, some addresses do require caution, including the earliest P2PK and the latest P2TR methods based on public keys. In contrast, hash-based forms such as P2PKH, P2SH, P2WPKH, and P2WSH are relatively safe. However, it is worth noting that reusing these addresses can also expose the public key, thereby posing potential risks.

Developers are not idle. Bitcoin has been continuously evolving, and in the future, solutions such as hash-based Lamport signatures may be introduced. There have been many discussions within the community, including applications in state management. Additionally, quantum-resistant algorithms based on lattice cryptography may also be introduced, which can be activated through soft forks.

In addition to technical upgrades, good usage habits can also effectively defend against Quantum Computing threats. For example, changing the receiving address for each transaction (one-time use) instead of reusing the same address. Furthermore, it is also wise to transfer assets to relatively safer isolated witness addresses before Quantum Computers pose a substantial threat.

Other blockchain networks, such as Ethereum, are also actively discussing post-quantum cryptography solutions, which can be introduced through hard forks.

It should be pointed out that the emergence of Quantum Computers will not only affect cryptocurrencies but will also impact many important areas such as traditional financial systems, national defense systems, and confidential communications.

In summary:

• In the short term, the threat of Quantum Computers to Bitcoin and other blockchain networks is not a major concern.
• However, users should develop good usage habits and continuously pay attention to the progress of Quantum Computing technology.