Baskin Logic Crypto Academy

Topic · New tech

Quantum computing and Bitcoin: what could break

By Joshua Baskin, founder · Reviewed · Sources

Where quantum risk to Bitcoin sitsSpending reveals your public key. A large future quantum computer could attack it. Unspent fresh addresses show only a hash. A fix needs new signatures and a soft fork.1Spending reveals your public key2A large future quantum computercould attack it3Unspent fresh addresses showonly a hash4A fix needs new signatures and asoft fork
Where quantum risk to Bitcoin sits

What is at risk

Bitcoin uses two kinds of cryptography. Signatures (ECDSA and Schnorr) prove you own coins. A large, error-corrected quantum computer running Shor’s algorithm could work out a private key from a public key. Hashing (SHA-256) secures mining and addresses; the known quantum speed-up there (Grover’s algorithm) is much smaller.

Which coins are exposed

Most addresses only show a hash of the public key until you spend. The public key is visible on chain for: very old pay-to-public-key outputs, reused addresses that have already spent, and Taproot outputs (which commit to a public key directly). Not reusing addresses reduces exposure.

When, and what is being done

No quantum computer today can do this; how many years it might take is debated. Bitcoin developers have proposed new quantum-resistant address types (for example BIP-360), which would need wide agreement and a soft fork. Any change would take years, which is why the discussion has started early.

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Common questions

Can quantum computers break Bitcoin today?

No. Current machines are far too small and error-prone.

Is mining at risk?

Much less. Grover’s algorithm gives only a modest speed-up against hashing.

Sources

  1. NIST Post-Quantum Cryptography
  2. NIST: first 3 finalized post-quantum standards (Aug 2024)
  3. Bitcoin Improvement Proposals

Sources checked October 23, 2026. Rules change; check the official source before acting.

Education only. Not investment, tax or legal advice. We do not pick coins.