Quantum Key Distribution
Key exchange secured by physics and not by math: any attempt to intercept the key disturbs it and gets noticed. Guides here cover how QKD works, where it’s being deployed, and how it stacks up against post-quantum cryptography.
// FAQ
What is quantum key distribution (QKD)?
QKD uses quantum physics to share an encryption key between two points so that any interception attempt disturbs the signal and can be detected. Read our no-math version.
Where is QKD deployed today?
QKD runs in government, finance, and some telecom networks, mostly as point-to-point links. See where QKD is deployed in 2026.
Why does QKD still require trust?
QKD protects the key exchange itself, but long-distance networks relay through trusted nodes, and physical hardware can be attacked. Our trusted-node problem and why “unbreakable” QKD still gets hacked guides explain.
Can QKD and post-quantum cryptography work together?
Yes. They address different parts of the problem, and some deployments combine them. Our guide explains how.
What is the no-cloning theorem and why does it matter?
It says an unknown quantum state cannot be copied perfectly, which is the physical basis for detecting eavesdropping in QKD. Read our no-cloning guide.
What are decoy states?
Decoy states are a security technique that made practical QKD with faint laser pulses possible by exposing photon-splitting attacks. See our decoy-states guide.
What is satellite QKD?
It uses satellites to relay quantum keys over distances fiber cannot reach. Our satellite QKD guide explains the model.
