Quantum computing and the future of Bitcoin security: risks, timelines, and next steps (2025)

Quantum advances are reshaping long‑term assumptions about digital security. While practical, large‑scale quantum computers do not exist yet, their eventual ability to break today’s public‑key cryptography would impact blockchains, financial systems, and the wider internet. Here is what matters now for Bitcoin and other crypto systems.

Why quantum threatens today’s cryptography

Most public‑key systems (e.g., RSA, ECC/elliptic‑curve) rely on problems like integer factorization and discrete logarithms. A future fault‑tolerant quantum computer running Shor’s algorithm could solve these efficiently, threatening confidentiality and signature schemes that protect software updates, wallets, and transactions.

Two practical risk modes:

• Storage risk: Funds at addresses with already‑revealed public keys could be targeted if corresponding private keys become derivable.
• Transit risk: If public keys are revealed in a transaction before confirmation, an attacker with sufficient quantum capability could attempt to forge a competing spend.

These risks are discussed in accessible terms by technology and policy bodies examining crypto‑asset exposure to quantum capabilities.

Post‑quantum cryptography and standardization

The main mitigation is migration to post‑quantum cryptography (PQC). In July 2022, the U.S. National Institute of Standards and Technology (NIST) announced the first set of candidate algorithms for standardization:

• CRYSTALS‑Kyber (encryption/key encapsulation)
• CRYSTALS‑Dilithium, FALCON, SPHINCS+ (digital signatures)

This standardization effort provides a path for future protocol upgrades and hybrid schemes that combine classical and PQC primitives.

Timelines and “harvest‑now, decrypt‑later”

Estimates for “Q‑Day” (when quantum breaks today’s public‑key crypto at scale) vary widely, often a decade or more away. But the threat to long‑lived data is immediate: adversaries can capture encrypted traffic today and decrypt it later when quantum capabilities arrive. Organizations should inventory cryptography, prioritize long‑lived/high‑value data, and plan staged migrations.

What crypto projects and institutions should do now

• Map cryptographic dependencies (wallets, nodes, consensus, signing, update channels).
• Track PQC standards and reference implementations; test hybrid key exchange/signing where appropriate.
• Prepare key‑rotation and address‑migration playbooks for users holding coins at reused/legacy addresses.
• Coordinate with exchanges, custodians, and hardware wallet vendors on PQC‑ready roadmaps.

Practical guidance for individual holders

• Avoid address reuse; prefer wallets that minimize public key exposure before spend.
• Stay current with client/wallet releases and security advisories.
• When community guidance is available, migrate coins from legacy/reused addresses to safer address types.

Looking ahead

Transitioning the internet and public blockchains to PQC will be a multi‑year program that requires standards, implementations, interoperability testing, and clear user guidance. Early planning reduces operational risk when upgrades become available.

last updated: 2025-09-07

References and Further Reading

1. NIST – NIST announces first four quantum‑resistant cryptographic algorithms (July 2022): https://www.nist.gov/news-events/news/2022/07/nist-announces-first-four-quantum-resistant-cryptographic-algorithms
2. Signal – Post‑quantum cryptography in Signal (PQXDH): https://signal.org/blog/pqxdh/
3. Canadian Centre for Cyber Security – Addressing the quantum computing threat to cryptography (ITSE.00017): https://www.cyber.gc.ca/en/guidance/addressing-quantum-computing-threat-cryptography-itse00017
4. World Economic Forum – Could quantum computers steal the bitcoins straight out of your wallet? (2022): https://www.weforum.org/agenda/2022/04/could-quantum-computers-steal-the-bitcoins-straight-out-of-your-wallet/
5. Reuters – Europol‑linked body: banks should prepare for quantum computer risk now (Feb 2025): https://www.reuters.com/technology/cybersecurity/europol-body-banks-should-prepare-quantum-computer-risk-now-2025-02-07/