Education
QKD vs PQC: what security teams confuse
Quantum key distribution (QKD) and post-quantum cryptography (PQC) both appear in quantum security conversations — but they are not interchangeable solutions for enterprise TLS migration.
Side-by-side comparison
| Post-quantum cryptography (PQC) | Quantum key distribution (QKD) | |
|---|---|---|
| Mechanism | New classical math (lattices, hashes) | Quantum physics (photon states) |
| Deploys on | Existing TLS, PKI, software stacks | Dedicated fiber/satellite links |
| NIST status | FIPS 203–205 finalized | Outside NIST PQC standardization |
| Enterprise TLS path | Primary migration route | Niche / specialized links |
NIST's PQC program standardizes algorithms software vendors integrate into OpenSSL, browsers, and HSMs. CISA guidance focuses on PQC migration for broad cyber infrastructure.
QKD detects eavesdropping on optical channels — valuable for specific high-assurance links — but does not replace PKI inventory and ML-KEM deployment across your SaaS estate.
What to tell leadership
- PQC migration is the 2024–2035 program aligned to NIST IR 8547 and CISA's factsheet.
- QKD may complement specialized links; it is not a substitute for finding RSA certificates on your CDN.
- The NCCoE migration project demonstrates software-based PQC tooling enterprises can adopt today.
This quarter
- Clarify terminology in your risk register: PQC = algorithm migration; QKD = physical key exchange.
- Inventory quantum-vulnerable software crypto regardless of QKD pilots.
- Watch NIST featured videos for official PQC explainers.
Continue on the Q-Day hub: What is Q-Day? guide
References & further reading
Authoritative primary sources cited in this article. Summaries are our own — follow links for full context.
Last verified 2026-06-21
- What Is Post-Quantum Cryptography?NIST · 2024Official overview of NIST's PQC project, finalized standards, and the harvest-now-decrypt-later threat model.
- CISA Post-Quantum Cryptography InitiativeCISA · 2024US government guidance on quantum risk, migration planning, and PQC adoption.
- CISA Quantum Readiness: Migration to Post-Quantum CryptographyCISA · 2024Executive factsheet on PQC migration steps for public and private sector organizations.
- NCCoE Migration to Post-Quantum Cryptography ProjectNIST NCCoE · 2024Practical migration demos, crypto discovery guidance, and industry collaboration.
- NIST Post-Quantum Cryptography — Featured VideosNIST · 2024Official NIST explainers on PQC standards, migration, and the standardization journey.
See your exposure with evidence
Run a live PQC inventory scan, export a CBOM, and verify signed reports independently.