Quantum Algorithms Database
BB84 Quantum Key Distribution
The first quantum key distribution protocol, allowing two parties to generate a shared secret key with security guaranteed by physics rather than mathematical assumptions.
Year
1984
Inventor(s)
Bennett & Brassard
Speedup Type
No Speedup Claimed
Difficulty
★★☆☆☆
The Problem
Establishing a shared secret encryption key between two parties in a way that reveals any eavesdropping attempt.
How It Works
Encodes key bits in the polarization of single photons; any attempt to intercept and measure them disturbs the quantum state in a detectable way, revealing eavesdropping.
Real-World Impact
Commercially deployed today in specific high-security contexts (banking, government); the conceptual foundation for all quantum cryptography that followed.