Google's recent release of the quantum computing chip Willow has once again sparked discussions in the community about whether 'quantum computing will destroy Bitcoin.' To help readers understand from multiple perspectives why quantum computing will not currently destroy Bitcoin, Wu said that Blockchain has compiled the views of three key opinion leaders.
Summary
Quantum computing will not currently destroy Bitcoin, but there is a potential threat. Because the quantum computing capability is still insufficient to break Bitcoin's hashing and signature mechanisms, current security is assured. However, Satoshi Nakamoto's million bitcoins, due to the use of early public key format (P2PK), are at risk of being compromised by quantum computing. The community can respond to future challenges by introducing quantum-resistant encryption or hard forks to freeze related assets.
Founder of Avalanche @el33th4xor
Despite the stunning recent advances in quantum computing, it does not currently pose a threat to cryptocurrency security. The reasons are as follows:
1. Differences in computational characteristics: Quantum computing has significant advantages in specific operations like factorization, but still struggles with others like reversing one-way hash functions. At the same time, the attack window for quantum computing is very short, making attacks extremely difficult.
2. Design against quantum attacks: Systems like Bitcoin only disclose the hash of the public key before transactions, not the public key itself, protecting the security of static funds. The public key is only revealed after the transaction is broadcasted, and quantum attackers need to crack the key in a very short time. For example, in Bitcoin, this window is about 5 to 30 minutes; in Avalanche, it is only 1 second.
3. Future defense solutions: Avalanche has submitted a request on GitHub to introduce quantum-resistant lattice encryption. Although the signature size is larger, the technology is well-prepared.
4. Satoshi Nakamoto's Bitcoin issue: The risk associated with the early adopted 'pay to public key' (P2PK) format may prompt the Bitcoin community to consider freezing these old format bitcoins as quantum computing threats increase.
Chief Analyst of HashKey Group Jeffrey Hu
The Bitcoin protocol can be simplified into two parts: mining (hash-based) and transactions (elliptic curve signature-based), both of which may be affected by quantum algorithms:
1. Current insufficient computing power: Attacking Bitcoin requires millions of physical quantum bits, while the Willow chip only has 105 physical quantum bits, far from being a threat level.
2. Limited impact on mining: Although Grover's algorithm can accelerate hash collisions, it does not break the hashing rules; it is just like a more powerful mining machine.
3. Signature security: Older P2PK and the latest P2TR need to be cautious, but formats based on hashes like P2PKH and P2SH are relatively safe. Address reuse may cause risks, so good usage habits are recommended, such as using one key at a time and transferring assets to more secure segregated witness addresses.
4. Future feasible measures: Introducing hash-based Lamport signatures or quantum-resistant lattice encryption can be implemented through soft forks.
Associate Professor Hu Yilin from Tsinghua University
Bitcoin's upgrades against quantum attacks may be difficult to completely resolve through soft forks, with the following challenges:
1. Old coin risks: Addresses with balances that once exposed public keys may not be able to transfer in time due to users losing their private keys or negligence, leading to a large number of 'resurrected' coins impacting the market. This requires a hard fork to permanently seal these old coins.
2. First-mover advantage: Early quantum computers may concentrate on seizing all dormant coins, which could have a dramatic impact on the market, especially if these technologies are held by large companies or governments.
