What is Post-Quantum Cryptography?
A beginner's guide to understanding post-quantum cryptography, why it matters, and what's being done about it.
Post-quantum cryptography researcher with a PhD from the University of Kent. Over 8 years of experience analyzing blockchain security and quantum computing threats.
Post-quantum cryptography (PQC) refers to cryptographic algorithms that are designed to be secure against attacks by both classical and quantum computers.
Why Do We Need It?
Current public-key cryptography (RSA, ECC, Diffie-Hellman) relies on mathematical problems that are hard for classical computers but can be efficiently solved by quantum computers using Shor’s algorithm.
The NIST Standardization
NIST has been running a multi-year competition to select and standardize post-quantum algorithms. In August 2024, they published three new standards:
ML-KEM (FIPS 203)
Based on the Module-Lattice Key Encapsulation Mechanism (formerly CRYSTALS-Kyber). Used for key exchange.
ML-DSA (FIPS 204)
Based on the Module-Lattice Digital Signature Algorithm (formerly CRYSTALS-Dilithium). Used for digital signatures.
SLH-DSA (FIPS 205)
Based on SPHINCS+. A hash-based signature scheme with different security assumptions.
When Should You Migrate?
The answer depends on your threat model:
- High-value, long-term secrets: Start now (harvest now, decrypt later attacks)
- General enterprise: Begin planning, pilot projects in 2025-2026
- Consumer applications: Follow platform/library updates
Getting Started
- Inventory your cryptographic usage
- Identify high-priority systems
- Test PQC algorithms in non-production environments
- Plan for hybrid deployments (classical + PQC)
- Monitor NIST and industry guidance
The transition to post-quantum cryptography is a marathon, not a sprint. Start planning now.
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