What is Post-Quantum Cryptography (PQC)?
Post-Quantum Cryptography (PQC) is a set of cryptographic algorithms designed to resist attacks from quantum computers. It protects data and communications against an adversary who has access to a large-scale quantum computer, which can break widely used algorithms such as RSA and elliptic-curve cryptography.
What it is
Post-Quantum Cryptography refers to mathematical algorithms that remain secure even when an attacker runs a cryptographically relevant quantum computer. Today's public-key systems, including RSA, Diffie-Hellman, and elliptic-curve cryptography, rely on problems that quantum algorithms such as Shor's algorithm can solve in polynomial time. PQC replaces or supplements those systems with problems believed to be hard for both classical and quantum computers.
The U.S. National Institute of Standards and Technology (NIST) finalized its first PQC standards in 2024. The primary algorithms are:
- ML-KEM (formerly CRYSTALS-Kyber): a key encapsulation mechanism based on lattice problems.
- ML-DSA (formerly CRYSTALS-Dilithium): a digital signature scheme based on lattice problems.
- SLH-DSA (formerly SPHINCS+): a hash-based digital signature scheme.
These algorithms can run in software, firmware, or dedicated hardware such as post-quantum TPMs and secure enclaves.
Why it matters
A sufficiently powerful quantum computer does not exist yet, but the threat is real for two reasons. First, adversaries can collect encrypted traffic today and decrypt it later once quantum hardware matures. This is called a "harvest now, decrypt later" attack. Second, migrating cryptographic infrastructure takes years. Organizations that handle long-lived secrets, classified data, or regulated records need to start migration planning now.
Sectors with the highest urgency include government, defense, financial services, healthcare, and critical infrastructure.
How tools address it
Products in the Quantum Security category address PQC in several ways:
- replace classical key exchange and signature algorithms with NIST-standardized PQC algorithms in existing applications.