Continuing our theme of learning about foundations of modern crypto algorithms, Robert introduced us to lattices. Specifically we covered:

  • What is a lattice
  • Shortest vector and closest vector problems (SVP, CVP)
  • The LLL algorithm for finding approximate solutions to the SVP
  • Learning with errors (LWE)
  • Reduction LWE to CVP
  • How hard is LWE in the grand scheme of things
  • How to use LWE for encryption
  • How do people actually use it for encryption: CRYSTALS Kyber

In the future we might also cover Dilithium signatures and fully homomorphic encryption, but this talk was already at the high end of information to give CTF players late in the evening.

The slides can be found here. The talk was held on the 23rd of February 2023.