Post-Quantum Cryptography (PQC)
Classical cryptography chosen to survive quantum attack: ordinary math no known classical or quantum computer can crack efficiently. No quantum hardware required.
Post-quantum cryptography (PQC) is the defense against Shor's algorithm, and the most common confusion in the field: it involves no quantum technology at all. PQC is ordinary software running ordinary math (lattice problems, hash trees) chosen because neither classical nor quantum computers are known to crack it efficiently.
NIST (the same agency whose Boulder labs build atomic clocks) standardized the first PQC algorithms in 2024, ML-KEM for key exchange, ML-DSA and SLH-DSA for signatures, and federal migration deadlines now stretch through 2035. The driver is 'harvest now, decrypt later': encrypted traffic recorded today becomes readable the day a cryptographically relevant quantum computer exists.
Distinguish PQC from quantum key distribution: PQC is math you can deploy with a software update; QKD is hardware that needs fiber and photons. The market overwhelmingly favors the software update.