The core of this talk demonstrates how the Enigma's complex encryption system can be elegantly modelled using functional programming principles in F#. We'll illustrate how the machine's components—rotors, reflector, and plugboard—naturally map to a pipeline of pure functions, with machine state threaded through using fold/reduce patterns. This approach not only simplifies the conceptual understanding of the Enigma but also highlights the expressive power of F# for modelling complex systems.

Finally, we'll explore comprehensive testing strategies for our implementation, including property-based testing to verify encryption/decryption symmetry and unit testing to validate the behavior of individual components. Through this journey, attendees will gain insights into both historical cryptography and modern functional programming techniques that remain relevant in today's software engineering practices.