Understanding Post-Quantum Cryptography
Post-quantum cryptography (PQC) refers to cryptographic systems that remain secure even when attacked by quantum computers. Current encryption standards — RSA, ECDSA, Diffie-Hellman — are all based on mathematical problems that Shor's algorithm can solve efficiently on quantum hardware. PQC replaces these with problems that resist quantum attacks.
Why Current Cryptography Fails
All major encryption used today relies on two mathematical problems: integer factorization (RSA) and discrete logarithms on elliptic curves (ECDSA). Both can be solved in polynomial time by Shor's algorithm on a quantum computer. This means every system using RSA or ECDSA — including Bitcoin, Ethereum, banking systems, and HTTPS — will eventually need to migrate to PQC.
The Five Families of PQC
- Lattice-based: Based on the difficulty of finding short vectors in high-dimensional lattices. Includes CRYSTALS-Kyber and CRYSTALS-Dilithium. This is the most practical and widely adopted family.
- Hash-based: Based on the security of cryptographic hash functions. Includes SPHINCS+ (NIST FIPS 205). Conservative but with larger signatures.
- Code-based: Based on decoding random linear codes. Classic McEliece is the primary candidate. Very large keys but well-studied.
- Multivariate: Based on solving systems of multivariate polynomial equations. Rainbow was a candidate but was broken in 2022.
- Isogeny-based: Based on maps between elliptic curves. SIKE was a promising candidate but was catastrophically broken in 2022 by classical computers.
NIST Standardization
After evaluating 82 candidate algorithms over 8 years, NIST published three standards in August 2024: FIPS 203 (ML-KEM/Kyber), FIPS 204 (ML-DSA/Dilithium), and FIPS 205 (SLH-DSA/SPHINCS+). These are now the global standard for quantum-safe cryptography.
PQC in Cryptocurrency
BMIC is the first cryptocurrency to implement NIST-standard PQC at the protocol level, using CRYSTALS-Kyber for key encapsulation and ERC-4337 for quantum-safe signatures on Ethereum. Most other cryptocurrencies have no PQC implementation plan.