The document discusses using symmetric encryption to provide confidentiality, noting the need to securely distribute shared keys between parties and alternatives like using a trusted third party. It also covers generating random numbers, which are important in cryptography, and sources of randomness like noise-based hardware generators as well as pseudorandom number generators that can pass tests for randomness. Placement of encryption at different layers in the OSI model and traffic analysis techniques are also summarized.

1. Cryptography and Network Security Third Edition by William Stallings Lecture slides by Lawrie Brown

10. Key Distribution Scenario