Quantum Cryptography
What is Quantum Cryptography?
Quantum CryptographyCryptography that uses quantum-mechanical properties — typically of photons — to achieve security guarantees impossible with classical communication alone.
Quantum cryptography exploits quantum-mechanical phenomena such as superposition, the no-cloning theorem, and measurement disturbance to provide information-theoretic security guarantees. Its best-known application is Quantum Key Distribution (QKD), with protocols like BB84 (Bennett-Brassard 1984), E91, and continuous-variable variants, which let two parties share a symmetric key over an optical channel while detecting any eavesdropping. Commercial QKD systems exist (e.g., ID Quantique, Toshiba) and are deployed over dedicated fiber or satellite links such as China's Micius. Quantum cryptography is not the same as post-quantum cryptography: it provides physically secure key exchange but requires specialised hardware and is currently distance-limited, so most agencies recommend post-quantum algorithms over QKD for general-purpose use.
● Examples
- 01
BB84-based QKD links between Beijing and Shanghai over the Chinese national quantum backbone.
- 02
Toshiba and ID Quantique commercial QKD systems for inter-data-center key exchange.
● Frequently asked questions
What is Quantum Cryptography?
Cryptography that uses quantum-mechanical properties — typically of photons — to achieve security guarantees impossible with classical communication alone. It belongs to the Cryptography category of cybersecurity.
What does Quantum Cryptography mean?
Cryptography that uses quantum-mechanical properties — typically of photons — to achieve security guarantees impossible with classical communication alone.
How do you defend against Quantum Cryptography?
Defences for Quantum Cryptography typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Quantum Cryptography?
Common alternative names include: Quantum key distribution, QKD.