This blog post describes the post-quantum cryptography (PQC) system Kyber, which is a finalist in NIST’s PQC competition. In the first section I’ll introduce post-quantum crypto and give some background on Kyber. Then I’ll describe the concrete system by looking at a minified version. The last section will cover remaining technical details and security claims. Kyber and Post-Quantum Crypto Already in the early 2000s cryptographers got increasingly worried about potential advances in quantum computing. Since Peter Shor published his famous Shor’s Algorithm we know that a large enough quantum computer would break all widely used public key systems.