Quantum Security
An overview of PQC, QKD, and lattice-based cryptography, the technologies that defend against the quantum computing threat.
I. Overview
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Definition: Security technologies developed to counter the threat that quantum computers’ immense computing power (such as Shor’s algorithm) poses to modern asymmetric-key cryptographic systems.
Features:
( Physical Security ) Blocks physical eavesdropping by exploiting the properties of quantum mechanics through Quantum Key Distribution (QKD)
( Use of Hard Mathematical Problems ) Strengthens security by using complex algorithms (PQC) that remain hard to solve even with a quantum computer
( Forward-Looking Response ) Protects existing cryptographic systems from quantum threats such as Shor’s algorithm
II. Mechanism & Components
A. Comparing QKD and PQC
| Comparison Item | Quantum Key Distribution (QKD) | Post-Quantum Cryptography (PQC) |
|---|---|---|
| Security Principle | Physical properties of quantum mechanics (superposition, no-cloning) | Hard mathematical problems (lattice, multivariate, code-based, etc.) |
| Implementation | Requires dedicated hardware and fiber-optic cable | Software upgrade (reuses existing infrastructure) |
| Transmission Distance | Distance-limited (signal attenuation) | No distance limit (works over any network segment) |
| Scalability | Low scalability due to hardware cost | High scalability, replacing existing crypto algorithms |
| Primary Purpose | Secure key exchange | Authentication, signing, and encryption across the board |
B. The Core of PQC: Lattice-Based Cryptography
Concept: A cryptographic method that exploits the mathematical hardness of the “Shortest Vector Problem (SVP)” or “Closest Vector Problem (CVP)” within an n-dimensional lattice structure.
Major algorithms: Kyber (public-key encryption/KEM) and Dilithium (digital signatures), both selected as NIST standards.
Features:
- Difficult to break not only by quantum computers but also by high-performance supercomputers
- Fast computation speed and relatively efficient key sizes
- Also used as the foundational technology for fully homomorphic encryption (FHE)
III. Advanced Topics & Comparison
| Stage | Initiative | Details |
|---|---|---|
| 1. Apply Hybrid Approach | Achieve crypto-agility | Combine existing cryptography with PQC to secure both security and compatibility at once |
| 2. Upgrade Infrastructure | Deploy QKD on national/enterprise core networks | Build physical network infrastructure for segments requiring extremely high trust, such as finance and defense |
| 3. Standardize and Transition | Adopt NIST standard algorithms | Gradually replace systems with standardized PQC algorithms (Kyber, etc.) |
Last updated 18 Aug 2026, 00:00 UTC.