Can a Quantum Computer Destroy Bitcoin? The Threat Is Your Keys, Not Mining — Research

Bitcoin broke $200,000 USD in 2025, according to CoinDesk, and crypto fever is back. A rumor travels with it on forums and on X: what if a quantum computer destroys Bitcoin? The picture most people have is a supercomputer mining every block in seconds. The real story is slower, and in some ways worse. This is the next piece in our Bitcoin series, after what mining is and why it does not pay in Mexico. Quantum computing does not threaten the mining race. It threatens the digital signatures that authorize your BTC. Spoiler: we are not in danger today, 17 June 2025. The quantum clock is still running, and Bitcoin has to move before it runs out.

The myth: a quantum machine would dominate mining

The usual claim is that a quantum computer would mine so fast it would vacuum up every reward (3.125 BTC per block, ~$625,000). That is a misunderstanding:

SHA-256 still holds: Bitcoin’s mining algorithm, SHA-256, is vulnerable to Grover’s algorithm, which gives a quadratic speedup (it shrinks a search of 2²⁵⁶ to 2¹²⁸). That remains computationally out of reach, according to Deloitte. A quantum machine would need trillions of qubits to outrun today’s ASICs (831 EH/s, per BTC.com).
Difficulty adjusts: Bitcoin recalculates difficulty every 2,016 blocks (~2 weeks) to keep a block at about 10 minutes. Any quantum edge would be absorbed, as Vitalik Buterin explained in a 2019 post.
Where the hardware is in 2025: Machines such as IBM Heron (4,158 qubits) lack error correction and enough logical qubits. Mining on them would be like bringing a pocket calculator to a classical supercomputer fight.

@CryptoCasey on X put it in one line: “Olvídense de la minería. Las cuánticas no van por los bloques, van por tus claves” — forget mining. Quantum machines are not after the blocks. They are after your keys.

The real risk: digital signatures and public keys

Bitcoin’s weak joint is ECDSA, the algorithm that produces the public and private keys that authorize transactions. When you send BTC, your public key lands on the blockchain. A sufficiently advanced quantum computer could then:

Break ECDSA: Using Shor’s algorithm, a machine with ~1,500–4,000 logical qubits could derive the private key from the public one in hours, according to a Nature study. That would let an attacker forge signatures and move funds.
Recovery phrases: Seed phrases (12–24 words) derive the private key. If the public key is exposed, the seed is in the blast radius too. Even without the public key, a future quantum machine could brute-force seeds — harder, but not unthinkable.
Who is most exposed: Wallets that reuse addresses, and “dormant” coins (10.7M BTC, ~50% of supply, per Glassnode). Exchanges with visible public keys would be targets as well.

A concrete case: if you spend BTC from an old address in 2035, a quantum attacker could steal whatever is left before the block confirms (10 minutes).

Are we in danger today?

No. In 2025, Bitcoin is safe against quantum computing:

Hardware limits: The most advanced machines (e.g. Google’s Willow, Quantinuum’s H2) have fewer than 10,000 physical qubits and no error correction. Forbes estimates it takes 1 million physical qubits (~1,500 logical) to break ECDSA, a milestone 10–20 years out.
Protections already in place: Unspent outputs (UTXOs) whose private keys have never been revealed stay safe until they are used. Taproot (Schnorr signatures) and cold wallets cut public-key exposure.
Mexico: With ~1.2 million crypto users in Mexico (Statista), the risk is global. Low cold-wallet adoption and heavy use of exchanges such as Bitso raise local vulnerability.

The risk still grows with time. @QuantumWatch on X: “Bitcoin está bien por ahora, pero en 2030, si no migramos a post-cuántica, será un caos” — Bitcoin is fine for now, but in 2030, if we have not moved to post-quantum cryptography, it will be chaos.

https://youtube.com/shorts/xvOxQAf5jVQ?si=YICfg9Qvxyaye16F

Can Bitcoin adapt?

Bitcoin is not doomed. It can evolve. That takes work:

Post-quantum algorithms: NIST has standardized schemes such as Dilithium and Falcon, which resist Shor. Bitcoin could ship them in a soft fork, similar to SegWit in 2017, according to Cointelegraph.
Community consensus: Replacing ECDSA needs miners, nodes, and developers to agree. The Bitcoin community is slow to converge (Taproot took three years), which could stall the move.
What users can do: Do not reuse addresses. Use hardware wallets (e.g. Ledger). Move old funds to post-quantum addresses when those exist.
Layer 2: Lightning Network and similar designs can keep more activity off the base chain, which means fewer public keys in the open.

A PwC article suggests Bitcoin could migrate to post-quantum algorithms by 2030. The transition will be messy, with risks of hard forks — or of lost funds if users never upgrade.

Risks and critiques

Quantum panic oversells the timeline. Complacency is also a mistake:

False safety: Some voices on X, such as @BitcoinBull, say “Bitcoin es indestructible” — Bitcoin is indestructible. Ignoring the quantum threat could leave millions exposed.
Development concentrated in a few hands: Relying on Bitcoin Core and a small group of developers to land post-quantum changes is a governance risk.
Mexico: Thin crypto literacy (~20% of Mexican users hold cold wallets, per Bitso) and dependence on centralized exchanges raise the cost of a quantum attack.
Technology hype: As with Builder.ai’s AI-washing or the metaverse, quantum computing is wrapped in exaggeration. Firms such as Google may talk up progress to attract capital and, as a side effect, manufacture panic.

Set beside Japan’s artificial blood (promise versus cost) or Google’s HeAR (real technical limits), the quantum threat is speculative — and still plausible.

What comes next: Bitcoin vs. quantum

Bitcoin has time to adapt. Not unlimited time. If the community moves before 2030, a soft fork could harden the network. Bitcoin’s own history (the 2017 block-size wars) shows how hard consensus is. In Mexico, the job for users is security: cold wallets, no long-term storage on exchanges, and attention to post-quantum upgrades when they ship. As @CryptoWhale wrote on X, “Bitcoin sobrevivirá, pero solo si no dormimos en los laureles” — Bitcoin will survive, but only if we do not rest on yesterday’s work. Quantum computing is not science fiction. It is a reminder that even digital gold has to keep changing. Next in the series: how to protect your BTC.

References

CoinDesk — Bitcoin Price Hits All-Time High Above $200K: https://www.coindesk.com/markets/2025/05/15/bitcoin-price-hits-all-time-high-above-200k
Deloitte — Quantum computers and the Bitcoin blockchain: https://www2.deloitte.com/nl/nl/pages/innovatie/articles/quantum-computers-and-the-bitcoin-blockchain.html
Nature — Quantum attacks on Bitcoin and how to protect against them: https://www.nature.com/articles/s41534-018-0078-4
Forbes — Quantum Leap Forward: The Race To Break Bitcoin: https://www.forbes.com/sites/digital-assets/2025/03/20/quantum-leap-forward-the-race-to-break-bitcoin
Cointelegraph — Post-Quantum Cryptography: Can Bitcoin Survive the Quantum Threat?: https://cointelegraph.com/news/post-quantum-cryptography-bitcoin-survive-quantum-threat
PwC — Quantum computing and blockchain: Opportunities and threats: https://www.pwc.com/gx/en/issues/blockchain/quantum-computing-and-blockchain.html