Post-Quantum Cryptography (PQC)
Next-generation cryptographic algorithms designed around mathematical problems that remain hard even for quantum computers.
I. Overview
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flowchart LR
A["Existing\npublic-key cryptography"] -- "Hard problems such as lattice-based math" --> B["Resistance to\nquantum computers"]
style A fill:#f9f9f9,stroke:#333,stroke-width:3px
style B fill:#e1f5fe,stroke:#01579b,stroke-width:3px
Definition: Next-generation cryptographic algorithms designed around complex mathematical problems that remain difficult to solve even with the immense computing power of a quantum computer.
Necessity:
( Responding to the Quantum Threat ) Preparing for the collapse of existing cryptographic systems due to the immense computing power of quantum computers
( Achieving Crypto-Agility ) A flexible cryptographic architecture is required so that new security threats can be responded to quickly
( Long-Term Security ) Proactively strengthens security for critical national infrastructure — public, financial, and defense sectors — in preparation for a future Q-Day
II. Mechanism & Components
A. Fundamental Principles and Transition Architecture
flowchart LR
A["Existing crypto\nRSA / ECC"] -->|"Quantum attack\n(Shor's algorithm)"| B["Q-Day\ndecryption threat"]
B --> C{"Transition method"}
C -->|"Transitional period"| D["Hybrid approach\nexisting + PQC in parallel"]
C -->|"Full transition"| E["PQC-only operation\n(NIST standard algorithms)"]
D --> F["Crypto-Agility\nachieved"]
E --> F
Key point: A “hybrid” approach — running existing cryptography alongside post-quantum cryptography — is emerging as the leading transitional strategy.
B. Major Algorithm Families by Mathematical Foundation
| Category | Mathematical Basis & Features | Representative Algorithms |
|---|---|---|
| Lattice-based | Uses the shortest vector problem (SVP) within a lattice structure; the most efficient and widely used approach | Kyber, Dilithium |
| Code-based | Uses the difficulty of decoding error-correcting codes; long track record of security validation, but larger key sizes | McEliece |
| Multivariate (MV) | Uses the difficulty of solving multivariate quadratic polynomial systems; fast signing speed | Rainbow |
| Hash-based | Uses the security of one-way hash functions; very strong quantum resistance | SPHINCS+ |
III. Advanced Topics & Comparison
- NIST Standardization: Compatibility with existing IT infrastructure must be validated around the standard algorithms selected by NIST (Kyber and others)
- Crypto-Agility: Establishing a flexible security architecture that can rapidly transition to a new cryptographic system is essential
- K-PQC Initiative: Developing a domestically suited post-quantum cryptographic algorithm and prioritizing its rollout in the public and financial sectors is an urgent task
Last updated 18 Aug 2026, 00:00 UTC.