Chapter 3 · QKD
The QKD chapter is the book’s most extensive technical and practical examination of quantum key distribution. It begins with the security logic of QKD: quantum measurements disturb states, eavesdropping raises error rates, and secure keys emerge only after sifting, error correction, privacy amplification, and authenticated classical communication. It then distinguishes major technology classes such as DV-QKD, CV-QKD, entanglement-based QKD, MDI-QKD, Twin-Field, and DI-QKD.
A major focus lies on implementation reality. The chapter reviews fiber-optic QKD, QKD networks, satellite systems, free-space links, and trusted-node architectures. It shows that real deployments remain heavily dependent on infrastructure, attenuation limits, environmental conditions, and trusted intermediaries. It also reviews device data, user experience, costs, and practical stability.
Crucially, the chapter highlights side-channel and implementation attacks, drawing a strong distinction between theoretical security proofs and real systems. It argues that procurement and operation must account for hardware imperfections, detector attacks, calibration manipulation, software risks, and the enlarged attack surface of trusted-node networks.
- Explains QKD protocol flow and assumptions
- Compares major QKD technology classes
- Reviews fiber, satellite, and free-space deployments
- Analyzes trusted-node and KMS dependence
- Emphasizes implementation and side-channel risks