Explore the fascinating world of cryptography and its mathematical foundations in this lecture from the 2018 Program for Women and Mathematics. Delve into various encryption techniques, including the Caesar Cipher, Monoalphabetic Substitution, and the Onetime Pad. Learn about frequency analysis and its role in decryption. Discover the concepts of key connections, daily keys, and permutations through practical examples. Gain insights into the historical development and modern applications of cryptographic methods from National Security Agency expert Toni Bluher.