The potential threat of quantum computing to Bitcoin mainly focuses on breaking elliptic curve encryption (ECDSA) and hash functions, but the actual risk depends on the development level of quantum computers and the measures taken by the Bitcoin network. Here are the key points analysis:

1. Areas potentially threatened by quantum computing

Elliptic Curve Digital Signature (ECDSA):

Bitcoin uses ECDSA to generate public-private key pairs for addresses. If a quantum computer can run the Shor algorithm, it could theoretically derive the private key from the public key (something classical computers cannot do). However, this requires the public key to be exposed (such as during transaction broadcasting).

Risk scenario: Bitcoin with reused addresses (public keys exposed for a long time) may be stolen.

Current situation: The Shor algorithm requires millions of qubits, while current quantum computers only have hundreds (such as IBM's 133 qubits) and have high error rates, far from practical levels.

Hash functions (such as SHA-256):

Quantum computers can use Grover's algorithm to accelerate hash cracking, but can only improve the brute force cracking speed from √N to √N (quadratic speedup), while SHA-256 itself remains secure (requiring 2¹²⁸ operations, which is difficult for quantum computers to achieve).

2. Bitcoin's defense measures

Unexposed public keys:

A Bitcoin address is a hash of the public key, not the public key itself. As long as the transaction is not broadcasted and the public key is not revealed, the Shor algorithm cannot attack.

Quantum-resistant signature schemes:

If the quantum threat approaches, Bitcoin can upgrade through forks to quantum-resistant signature algorithms (such as Lamport signatures, XMSS, etc.), which cannot be broken even by quantum computers.

One-time addresses:

Users should use a new address for each transaction (Best Practice), which can significantly reduce the risk of public key exposure.

3. Timeline and reality

Maturity of quantum computers:

Experts estimate that building a quantum computer capable of breaking ECDSA will take at least 10-30 years (and will require error-correcting qubits and very low error rates).

Response time of the Bitcoin community:

Even if quantum computers suddenly emerge, the Bitcoin network can respond with rapid upgrades (such as emergency hard forks).

4. Conclusion

Short-term (within 10 years): The threat of quantum computing to Bitcoin is extremely low; existing technology cannot break ECDSA or SHA-256.

Long-term: If quantum computers break through technical barriers, Bitcoin can resist risks through protocol upgrades, but reused old addresses may face risks.

Recommendation: Users should avoid reusing addresses and keep an eye on the progress of quantum-resistant encryption. The decentralized nature of Bitcoin gives it strong adaptability and will not be easily 'cracked' by quantum computing.