Human Factors and missed solutions to Enigma design weaknesses

The German World War II Enigma suffered from design weaknesses that facilitated its large-scale decryption by the British throughout the war. We show that the main technical weaknesses (self-coding and reciprocal coding) could have been completely avoided using simple contemporary technology, and therefore the true cause of the weaknesses is not technological but must be sought elsewhere. Specifically, Human Factors issues resulted in the persistent failure to seek out more effective designs. Similar blindspots persist in the Enigma literature, which misunderstands the weaknesses and therefore inhibits broader thinking about design, and realising the critical role of Human Factors for cryptography.
Harold Thimbleby is professor of computer science at Swansea University, Wales. His passion is designing dependable systems to accommodate human error, especially in healthcare.

Harold wrote the book Press On, which won the American Publishers' Association best book award in computer science.

Harold is an Honorary Fellow of the Royal College of Physicians, a Fellow of the Royal College of Physicians, Edinburgh, the Institute of Engineering Technology, the Learned Society of Wales, and an Honorary Fellow of the Royal Society of Arts. Harold has been a Royal Society Wolfson Research Merit award holder and a Royal Society Leverhulme Trust Senior Research Fellow. He is Emeritus Gresham Professor of Geometry.