# 「Cryptography-MIT6875」: Lecture 6 - Number Theory

**Topics covered:**

- Groups, Order of a group and the Order of an element, Cyclic Groups.
- The Multiplicative Group $\mathbb{Z}_N^*$ and $\mathbb{Z}_P^*$ for a prime $P$.
- Generators of $\mathbb{Z}_P^*$.
- Primes, Primality Testing.
- The Discrete Logarithm (DLOG) problem and a candidate OWF.
- Diffie-Hellman assumptions: DDH and CDH.