Prepping for post-quantum: a beginner’s guide to lattice cryptography

This post introduces lattice cryptography as a foundational element for post-quantum (PQ) cryptography, explaining its application in key exchange protocols like ML-KEM. It details the mathematical concepts of matrices, modular arithmetic, matrix transpose, matrix multiplication, and matrix addition as they apply to lattice-based cryptography. The post provides a simplified Python implementation using NumPy to illustrate how these operations can be used to establish a shared secret, analogous to Diffie-Hellman key exchange, while highlighting the significantly larger communication overhead of lattice-based schemes compared to current elliptic-curve cryptography.