The threat of quantum computing to Bitcoin private keys is an important issue in the cryptocurrency field, but there is currently no clear timeline.

Here are the key points of analysis:

1. Current Progress in Quantum Computing

- Difficulty of breaking ECDSA: Bitcoin uses the Elliptic Curve Digital Signature Algorithm (ECDSA), with a private key length of 256 bits. Theoretically, a quantum computer could break this using Shor's algorithm in polynomial time, but it would require millions of physical qubits (the most advanced IBM quantum processor today has only a little over a thousand qubits, and has a high error rate).

- Actual requirements: Breaking 256-bit ECDSA would require about 500-3000 logical qubits (after error correction), and one logical qubit may need thousands of physical qubits to support it. Optimistically, it is estimated that it will take at least 10-20 years to reach this level.

2. Transition to Quantum-Resistant Algorithms

Challenges of upgrading Bitcoin: Even if quantum computing matures, Bitcoin will need to upgrade to quantum-resistant signature algorithms (such as Lamport signatures, XMSS, or SPHINCS+). Community consensus and miner support are key, and this may lead to controversy or delays.

- Proactive defense: Some projects (like QRL, IOTA) have already deployed quantum-resistant solutions, but Bitcoin's large ecosystem makes its upgrade more complex.

3. Time Estimates

Conservative estimate: Without significant technological breakthroughs, the threat of quantum computers to Bitcoin will take at least 15-30 years.

- Risk window: If quantum computing suddenly advances, unused old addresses (with exposed public keys) may be the first to be attacked, while new transactions (using new algorithms) may be safer.

4. Other Influencing Factors

- Error correction and stability: Current qubits are easily affected by noise, and error correction technology is still immature.

Cost-effectiveness: Attacking Bitcoin may not be as attractive as breaking military or financial encryption systems, and the actual threat may lag behind technological capabilities.

In the short term (within 10 years), the possibility of Bitcoin private keys being broken by quantum computing is extremely low, but in the medium to long term, attention should be paid to quantum advancements and community responses. It is recommended that holders focus on quantum-resistant upgrades in the future and avoid reusing addresses to reduce risk.