Rahul Ilango, of the Institute for Advanced Study, lays out a complexity-theoretic approach to constructing cryptographic primitives that have long eluded researchers. He explains how circuit obfuscators, tools that scramble a program's implementation while preserving its function, can be used to carry statements from complexity theory directly into cryptographic constructions. The talk traces how this method has already yielded public-key encryption with what Ilango calls optimal security, work done jointly with Alex Lombardi. Delivered as part of the IAS Computer Science and Discrete Mathematics seminar series, the lecture assumes no background in cryptography and builds the ideas from basic principles, framing fifty years of cryptographic progress and the gaps that remain. It runs just over two hours, giving room for the technical argument to unfold along with audience questions.