What Is Post-Quantum Cryptography?
Post-quantum cryptography (PQC) is the field of cryptographic algorithms designed to be secure against attacks by both classical and quantum computers. NIST standardized the first three PQC algorithms in August 2024: CRYSTALS-Kyber (FIPS 203), CRYSTALS-Dilithium (FIPS 204), and SPHINCS+ (FIPS 205). PQC differs from quantum cryptography (QKD). PQC runs on classical hardware and resists quantum attacks via mathematical problems (lattices, hashes, codes, multivariate polynomials, isogenies) with no known quantum polynomial-time solution. NIST began standardization in 2017 with 82 submissions; finalized FIPS 203/204/205 on August 13, 2024.
TL;DR: Post-quantum cryptography (PQC) is the field of cryptographic algorithms designed to be secure against attacks by both classical and quantum computers. NIST standardized the first three PQC algorithms in August 2024: CRYSTALS-Kyber (FIPS 203), CRYSTALS-Dilithium (FIPS 204), and SPHINCS+ (FIPS 205). For full context including dates, sources, and the BMIC implication, see below.
- Is PQC the same as quantum cryptography? No. PQC runs on classical hardware. Quantum cryptography (QKD) requires quantum hardware.
- When did NIST finalize PQC? August 13, 2024 — FIPS 203, 204, 205.
- Has any PQC been broken? Rainbow (2022) and SIKE (2022) were broken. The NIST winners (Kyber, Dilithium, SPHINCS+) remain secure.
- How is BMIC related to PQC? BMIC implements CRYSTALS-Kyber per FIPS 203 at the Layer 1 protocol level.
- Will PQC replace AES? No. AES-256 with doubled key length (Grover defense) remains secure. PQC replaces RSA/ECDSA.
Full Answer
PQC is necessary because Shor's algorithm (1994) breaks RSA, DSA, and ECDSA on a sufficiently large quantum computer. Grover's algorithm halves the effective key length of symmetric ciphers (AES-256 becomes effectively AES-128).
Five families of PQC: lattice-based (Kyber, Dilithium, NTRU), hash-based (SPHINCS+, XMSS), code-based (Classic McEliece), multivariate (Rainbow — broken in 2022), isogeny-based (SIKE — broken in 2022).
NIST winners (Aug 2024): Kyber for KEM, Dilithium for signatures, SPHINCS+ for stateless hash-based signatures. Falcon (FIPS 206) is in final draft.
Adoption: Cloudflare TLS, Chrome, iMessage, Signal, AWS KMS, Open Quantum Safe (OQS) library. BMIC implements Kyber at the Layer 1 protocol level.