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Security Fundamentals & Crypto · Advanced

Quantum Key Distribution (QKD)

Method that uses quantum properties of photons to distribute keys with eavesdropping detection.

Definition

QKD protocols such as BB84 detect interception because measuring quantum states disturbs them. QKD requires specialized hardware and dedicated fiber or free-space links, has distance limits, and does not authenticate endpoints by itself. NSA and several European agencies do not recommend QKD for national security systems, favoring PQC.

Example

Two bank data centers 50 km apart exchange AES keys over a dedicated QKD fiber link.

Exam tip

QKD is not post-quantum cryptography; it needs quantum hardware and still needs classical authentication.

Don't confuse it with

Related terms