Explore the fascinating world of cryptography in this public lecture by Cris Moore at the Santa Fe Institute. Delve into the evolution of secret communication methods, from ancient techniques like invisible ink to modern e-commerce encryption based on prime numbers. Discover how cryptosystems function, tracing their development from Caesar and the Kama Sutra to contemporary digital security. Gain insights into the potential impact of quantum computers on current encryption methods and learn about emerging cryptographic techniques that may withstand quantum computing challenges. Understand complex concepts through accessible explanations, requiring only high school-level mathematics. Journey through topics such as frequency analysis, modular arithmetic, factoring, quantum mechanics, error-correcting codes, and group representation theory. Explore the implications of these advancements for privacy and security in a rapidly evolving technological landscape.