Unlocking the Secrets of the Enigma Machine: A Deep Dive by Isaac Abraham at NDC Copenhagen 2025 🕵️‍♂️

This talk was recorded at NDC Copenhagen in Copenhagen, Denmark. #ndccopenhagen #ndcconferences #developer #softwaredeveloper

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This presentation explores the infamous Enigma encryption device through the lens of functional programming. Starting with the historical context of the Enigma machine in World War II, we'll examine its design, operational mechanics, and the critical vulnerabilities that ultimately enabled Allied cryptanalysts to break what was once considered unbreakable.

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.