What is Quantum Key Distribution?
A method of using quantum mechanics to securely distribute encryption keys, where any eavesdropping attempt physically disturbs the quantum state and is detectable.
Also known as: QKD
QKD uses the fundamental properties of quantum physics to create theoretically unbreakable key exchange.
How It Works
- Photons are sent with random polarizations encoding key bits
- Measuring a photon changes its state (Heisenberg uncertainty principle)
- If an eavesdropper intercepts photons, the disturbance is detectable
- Only undisturbed transmissions are used for the key
Limitations
- Requires specialized hardware (quantum optical equipment)
- Limited range (~100km over fiber without quantum repeaters)
- Expensive and not widely deployed
- Vulnerable to implementation attacks (not theoretical attacks)
Current Status
- China has deployed a QKD network spanning thousands of kilometers
- Several European QKD testbeds are operational
- Not practical for consumer use in the near future
- Post-quantum cryptography (software-based) is the practical solution for now
Related Terms
Key Exchange
A cryptographic protocol that allows two parties to establish a shared secret key over an insecure channel. This shared key can then be used for symmetric encryption, enabling secure communication without prior contact.
Post-Quantum Cryptography
Cryptographic algorithms designed to resist attacks from both classical and quantum computers — the next generation of encryption being standardized to replace RSA, ECC, and other vulnerable algorithms.
Quantum Computing Threat
The risk that sufficiently powerful quantum computers will break widely-used encryption algorithms, potentially exposing all currently encrypted data.
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