Does Quantum Computer Pose a Threat to Bitcoin? No Need to Overly Worry in the Short Term

Will quantum computers destroy Bitcoin? This controversial topic often sparks widespread discussion. With Google’s recent release of the Willow quantum processor, this question has once again become a focal point. After research, we have come to the following conclusion:

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

From a simplified perspective, the Bitcoin protocol mainly consists of two parts: hash-based mining and elliptic curve transaction signatures. These two parts may indeed be affected by Quantum Computing, corresponding to Grover’s algorithm and Shor’s algorithm respectively.

However, Willow’s current “computing power” is far from sufficient to have a substantial impact on these two parts. To attack the hashing and signing system of Bitcoin within a reasonable time, about several thousand logical qubits are needed. Depending on different processes, it may require thousands of physical qubits to encode into 1 logical qubit.

This means that attacking Bitcoin would require about millions of physical quantum bits. However, Willow only has 105 physical quantum bits, which is far from the required amount.

If future Quantum Computers have sufficient computing power to pose a threat, then the impact on mining is relatively limited. Grover’s algorithm only accelerates the computation process and does not fundamentally break the hashing rules; it still requires a large amount of computation to find the desired hash value. It can be understood as the emergence of a new type of efficient mining device in the market.

Regarding address signatures, some addresses do require caution, including the earliest P2PK and the latest P2TR, which are based on public key methods. On the other hand, hash-based forms such as P2PKH, P2SH, P2WPKH, and P2WSH are relatively safe. However, it is important to note that reusing these addresses can also expose the public key, posing potential risks.

Developers can take measures to address this challenge. Bitcoin has been evolving continuously, and in the future, solutions such as hash-based Lamport signatures may be introduced. The community has engaged in extensive discussions on this topic, such as exploring the application of Lamport signatures in terms of state.

In addition, technologies such as anti-quantum lattice cryptography can also be introduced. These improvements can be achieved through a soft fork.

Apart from the development level, good usage habits can also effectively defend against quantum threats. For example, changing the receiving address each time (one address per transaction) instead of reusing addresses, and transferring assets to relatively secure isolated witness addresses before Quantum Computers pose a significant threat.

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

It is worth noting that the emergence of Quantum Computers will not only impact Bitcoin or other cryptocurrencies, but will also affect many important areas such as the traditional financial system, defense systems, and secure communications.

In summary:

• There is no need to overly worry about the threat of Quantum Computers to networks like Bitcoin in the short term.
• However, it is recommended to develop good usage habits and keep an eye on the progress of Quantum Technology.