# What is Quantum Computing Security?

> Quantum computing security is the practice of assessing and managing how quantum computing affects information security, cryptographic dependencies, and any quantum-enabled systems an organization uses.

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## Content

For most organizations, the immediate focus is readiness for a future cryptographically relevant quantum computer: finding vulnerable public-key cryptography, estimating how long protected data must remain secret, and planning controlled migration before exposure becomes practical.

The discipline is broader than choosing a post-quantum cryptography (PQC) algorithm. It includes governance, data-retention horizons, cryptographic inventories, protocol and certificate dependencies, suppliers, replacement constraints, testing, crypto agility, incident planning, and the secure retirement of old keys and algorithms.

### Key points

- **Threat and time horizon:** Relate plausible quantum capabilities to the algorithms in use, the confidentiality life of stored or intercepted data, the authenticity life of signatures, and realistic migration lead times.
- **Dependency inventory:** Trace cryptography through applications, libraries, hardware security modules (HSMs), certificates, firmware, devices, archives, partner protocols, and managed services, including systems that cannot be upgraded easily.
- **Roadmap and agility:** Assign ownership, require supplier plans, test approved replacements, manage hybrid or transitional designs carefully, prevent downgrade, and preserve the ability to change algorithms and parameters again.
- **Important limitation:** The arrival date and capabilities of a cryptographically relevant quantum computer remain uncertain, and inventories or discovery tools will miss dependencies. PQC migration reduces particular cryptographic risks; it does not resolve weak implementations, endpoints, identities, access controls, or every threat to quantum systems.

### Related terms

[Post-quantum cryptography (PQC)](<https://yellowcube.eu/glossary/post-quantum-cryptography/>) · [Quantum key distribution (QKD)](<https://yellowcube.eu/glossary/quantum-key-distribution/>) · [Cryptography](<https://yellowcube.eu/glossary/cryptography/>) · [Public key infrastructure (PKI)](<https://yellowcube.eu/glossary/public-key-infrastructure/>) · [Data governance](<https://yellowcube.eu/glossary/data-governance/>)

### Sources

[NIST National Cybersecurity Center of Excellence, Migration to Post-Quantum Cryptography: Frequently Asked Questions](https://pages.nist.gov/nccoe-migration-post-quantum-cryptography/) · [NIST CSWP 39 Update 1, Considerations for Achieving Crypto Agility](https://csrc.nist.gov/pubs/cswp/39/upd1/considerations-for-achieving-crypto-agility/final) · [CISA, NSA, and NIST, Quantum-Readiness: Migration to Post-Quantum Cryptography](https://www.cisa.gov/sites/default/files/2023-08/Quantum-Readiness%20-%20Migration%20to%20Post-Quantum%20Cryptography_508c.pdf)

## Attribution and scope

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