Demystifying the Enigma Machine - a Functional Journey by Isaac Abraham

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. Isaac Abraham I'm the founder of Compositional IT, a software consultancy specialising in functional-first, cloud-ready solutions. My background is technical - I've been using the .NET platform since its initial release, along with several years experience on Microsoft Azure. I have a background spanning both public and private sector clients in a variety of industries. I am particularly interested in functional and distributed programming, and its application through F# on the .NET platform; a regular speaker and contributor to the F# community, I have been a Microsoft F# MVP since 2014 - one of just a handful worldwide. I have also worked as CTO and director of one of the UK's leading Azure consultancies, particularly with regards to data-driven workloads. https://www.linkedin.com/in/isaacabraham/ Venue sponsor - Kivra https://kivra.se/ Video sponsor – Ada Beat https://adabeat.com Merch If you want to spread functional programming and support the channel, buy something from the shop: https://funcprogsweden.myspreadshop.net/ Chapters: 00:00 Intro by Magnus Sedlacek 02:28 Welcome Isaac Abraham 04:12 Demystifying the Enigma Machine - a Functional Journey by Isaac Abraham 05:44 Why Enigma? 06:23 Agenda 06:54 The Enigma machine 07:25 Basic function of Enigma 08:14 Core components 09:05 Why was it revolutionary 09:54 Origins of the Enigma 10:29 Military adoption 11:13 Scale of use in WW2 11:50 Perceived security 12:19 The hidden secret 13:06 Encryption principals 13:51 The rotors – engineering the cipher 14:41 The reflector 15:27 The plugboard 15:58 Complete signal path 17:00 Daily key procedures 18:51 Demo 1 23:07 Breaking the unbreakable – The Polish 24:06 Bletchley Park 25:38 Life of Alan Turing 27:19 The Turing test: Can machines think? 28:11 Turing and the Bombe 29:50 Mathematical weakness 30:31 Operational weakness 31:52 Impact of breaking Enigma 32:52 Modelling the Enigma in code 33:11 A word of warning 34:28 Look ma no objects 35:56 Modelling components as functions 36:32 Signal path as function composition 38:06 Handling state changes 39:10 Demo 2 55:46 Functional model benefits 56:36 Testing 58:56 Testing demo 01:02:53 The lost legacy 01:04:43 Lessons for modern security 01:05:13 Functional programming takeaways 01:07:13 Q&A #funcprogsweden