Could Quantum Computing Eventually Crack Bitcoin’s Private Keys?

[Lexandroove]

I’ve read a lot about quantum computing lately, and I believe significant levels of caution are warranted.

Bitcoin uses a system called elliptic curve cryptography to prove who owns what, where every wallet has two keys: a private key, which is a secret number, 256 digits long in binary, roughly as long as this sentence, and a public key that is derived from the private key by performing a mathematical operation on the specific curve.

Skipping all the intricacies that forms Bitcoin’s cryptography, the major point of worry is that Quantum computers that also run on Shor's algorithm (https://www.coindesk.com/tech/2026/04/05/a-simple-explainer-on-what-quantum-computing-actually-is-and-why-it-is-terrifying-for-bitcoin) can turn a Bitcoin public key into the private key that controls the coins, which for coins transacted since Taproot (a privacy upgrade on Bitcoin that went live in November 2021), the public key is already visible, while for coins in older addresses, the public key is hidden until you spend, at which point you have roughly nine minutes before the attacker catches up.

It’s a gaping loophole that I’m yet to see reliable structures in place to address competently. What are y’all thinking about the future of Bitcoin and quantum computing, and do you think that these concerns are legit? (I’m aware that the nine-minute attack scenario depends on a sufficiently powerful, fault-tolerant quantum computer, which does not currently exist, but I still see it as a concern, as it is achievable in the near future.

[NotFuzzyWarm]

Oh Lord, yet another QC fears thread..,  
This has been discussed to death here. Just scroll through the 1st page or at most 2 and you find at least a dozen of these threads fully covering it.

To sum them up:
Yes someday it can crack sha256- and  Bitcoin is far down the list as to what will be affected.
QC development is nowhere near being a relevant threat and won't be for at least another decade or more.
Yes there are proposals as to what to do before the QC threat is real.

[stadus]

Actually, if you had taken the time to search before creating this thread, you would have seen that there are already a lot of topics about QC that were created before.

Here are some of those topics, you can read through them, and I'm sure you'll find the answers to your questions.

Previous Discussions

• I would like to know your opinion on Bitcoin and quantum computers
• Will a quantum computer kill Bitcoin?
• Bitcoin and quantum computer fud
• Quantum computing and Bitcoin's integrity: what is actually at risk
• Quantum-Resistant Bitcoin: Is it time to replace ECDSA before it's too late?
• How feasible is migration to Quantum-Resistant Signatures in Bitcoin?
• [Draft BIP] Quantum-Resistant Transition Framework for Bitcoin
• Quantum Computing and Satoshi's Bitcoins

[hd49728]

Actually, if you had taken the time to search before creating this thread, you would have seen that there are already a lot of topics about QC that were created before.

Here are some of those topics, you can read through them, and I'm sure you'll find the answers to your questions.

The answer is simple and there are bigger concerns than Bitcoin.

Bitcoin market cap and Bitcoin trading volume are smaller than many other things, other assets, other markets so there are bigger ones have to face with bigger security threats from quantum computers than Bitcoin will face with.

They have weaker security than Bitcoin blockchain has so if quantum computers will reach to a computational power to attack financial systems, banks will have to worry first, then governments. I won't say if there will be such time, Bitcoin blockchain and private keys will be safe but Bitcoin will have some more time to buy and migrate to new algorithm against quantum computers.

[Lexandroove]

Oh Lord, yet another QC fears thread..,  
This has been discussed to death here. Just scroll through the 1st page or at most 2 and you find at least a dozen of these threads fully covering it.

To sum them up:
Yes someday it can crack sha256- and  Bitcoin is far down the list as to what will be affected.
QC development is nowhere near being a relevant threat and won't be for at least another decade or more.
Yes there are proposals as to what to do before the QC threat is real.

It has been discussed extensively, and yes, the threat might still be a distance away, but repeated discussion doesn't make the underlying question irrelevant.

The concern isn't just when quantum computers become powerful enough; it's whether Bitcoin can coordinate a secure migration before that happens.

I'm not arguing that Bitcoin is doomed—I'm asking whether the preparation is sufficient. That's a worthwhile discussion even if the threat is still years away

[Lexandroove]

Actually, if you had taken the time to search before creating this thread, you would have seen that there are already a lot of topics about QC that were created before.

Here are some of those topics, you can read through them, and I'm sure you'll find the answers to your questions.

The answer is simple and there are bigger concerns than Bitcoin.

Bitcoin market cap and Bitcoin trading volume are smaller than many other things, other assets, other markets so there are bigger ones have to face with bigger security threats from quantum computers than Bitcoin will face with.

They have weaker security than Bitcoin blockchain has so if quantum computers will reach to a computational power to attack financial systems, banks will have to worry first, then governments. I won't say if there will be such time, Bitcoin blockchain and private keys will be safe but Bitcoin will have some more time to buy and migrate to new algorithm against quantum computers.

Of course, traditional financial systems could face serious quantum-related risks too, potentially making the threat much broader than Bitcoin, but its smaller market cap doesn't automatically mean its cryptographic risk is less significant, as the issue is whether exposed public keys can be exploited and funds stolen.

I agree that Bitcoin may have time to adapt, but migrating to quantum-resistant cryptography across a decentralized network requires coordination and user participation.

The worry is if this transition can be completed in time before the threat becomes practical.