Explore advanced cryptographic concepts in this comprehensive lecture on oblivious structures, key-exchange protocols, and group messaging. Delve into topics such as Oblivious RAM, homomorphic secret sharing, and polynomial factoring. Examine the intricacies of group messaging, including round-based communication and symbolic models. Gain insights into Secure Group Messaging and Continuous Group Key Agreement, analyzing their security aspects and previous works. Discover two significant contributions in the field and participate in a thought-provoking discussion on the future of cryptographic protocols for secure communication.