Some Important QKD Protocols

Piller, Ernst; Schölnast, Hubert

Content of this appendix

Appendix 04 · Some Important QKD Protocols

This appendix surveys important QKD protocols and explains how they differ in physical assumptions, implementation requirements, and security models. It covers protocol families such as BB84, decoy-state approaches, entanglement-based protocols, continuous-variable variants, measurement-device-independent QKD, Twin-Field QKD, and device-independent ideas.

The appendix is not limited to abstract protocol names. It connects each family to practical questions: required transmitters and detectors, sensitivity to losses, achievable distances, calibration burden, vulnerability to implementation attacks, and suitability for fiber, free-space, or satellite scenarios. This makes the protocol overview relevant for readers comparing real systems.

A central theme is that stronger theoretical security claims often come with harder implementation requirements. The appendix therefore helps readers understand why vendor systems, field trials, and standardization work may focus on different protocol classes depending on cost, maturity, and operational constraints.

Introduces major QKD protocol families
Relates protocols to hardware and channel requirements
Compares security assumptions and implementation burden
Explains practical trade-offs in real deployments
Supports interpretation of vendor and research claims

Suggested citation

Reference in IEEE style

E. Piller and H. Schölnast, “Appendix 04: Some Important QKD Protocols,” author-maintained supplementary material for Data Encryption at the Intersection of Mathematics and Physics: Comparing Physical Methods of Cryptography, 2026. [Online]. Available: https://cryptography.study/phys/protocol/.

Reference in ACM style

Ernst Piller and Hubert Schölnast. 2026. Appendix 04: Some Important QKD Protocols. Author-maintained supplementary material for Data Encryption at the Intersection of Mathematics and Physics: Comparing Physical Methods of Cryptography. https://cryptography.study/phys/protocol/

BibTeX entry

@misc{piller_schoelnast_2026_appendix_04_qkd_protocols,
  title        = {Some Important QKD Protocols},
  author       = {Ernst Piller and Hubert Schölnast},
  year         = {2026},
  howpublished = {Author-maintained supplementary material for Data Encryption at the Intersection of Mathematics and Physics},
  url          = {https://cryptography.study/phys/protocol/},
  note         = {Related book DOI: 10.1007/978-3-032-24764-3},
  language     = {en}
}

RIS entry

TY  - GEN
TI  - Some Important QKD Protocols
T2  - Author-maintained supplementary material for Data Encryption at the Intersection of Mathematics and Physics
AU  - Piller, Ernst
AU  - Schölnast, Hubert
PY  - 2026
UR  - https://cryptography.study/phys/protocol/
N1  - Related book DOI: 10.1007/978-3-032-24764-3
LA  - en
ER  -

CSL JSON entry

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