Quantum Key Distribution: Unbreakable Cryptography with QKD
Quantum Key Distribution (QKD) uses quantum mechanics to detect eavesdropping. This guide implements the BB84 protocol with practical security considerations.
BB84 Protocol Simulation
The foundational QKD protocol using photon polarization:
Practical QKD Implementation
Integration with existing classical infrastructure:
Warnings ⚠️
Implementation Attacks: Real QKD systems have been hacked via detector blinding, Trojan horses, and timing side-channels. Theoretical security ≠ implementation security.
Distance Limitations: QKD range is limited to ~100km for fiber, 1000km for satellites. Quantum repeaters remain experimental.
Classical Channel Security: BB84 requires authenticated classical channel. If Eve controls this, the protocol fails.
Cost: QKD hardware is expensive ($50k-$500k per endpoint). Consider post-quantum classical crypto first.
Related Chronicles: The Quantum Intercept (2036) - When implementation flaws exposed "secure" quantum networks
Tools: Qiskit, QuTiP, ID Quantique commercial systems
Research: BB84 (Bennett & Brassard 1984), E91 protocol, device-independent QKD