Abstract:
It is well-known that the Allies won the important cryptographic battles in WWII: both the German ENIGMA cipher and many Japanese cryptosystems were systematically compromised by the Allies. However, a certain triumphalism has crept into accounts of the cryptographic war, which obscures both its seesaw nature and the fact that the final Allied success were highly conditional. At the start of the war, the Germans and the Allies were pretty closely matched; and the Germans were not alone in making serious blunders that compromised important cryptosystems. In this talk, I will describe both some German and Allied blunders, and try to account for why Germany lost the cryptographic contest in WWII. I will have to explain some aspects of the relevant cryptosystems to do that, but I will keep the technical aspects to a minimum. I will propose that four basic attitudes and assumptions of the German leaders were largely responsible for their failure to detect Allied penetration of ENIGMA, and for blunting key parts of their cryptanalytic efforts, thus losing the cryptographic war for them. However, most authors agree that this loss may have delayed, but probably did not change, the outcome of the War in general.
An excellent, highly-readable summary of a key struggle over ENIGMA is given in • David Kahn’s book, “Seizing the Enigma: the race to break the German U-boat codes, 1939-1943,” Houghton-Mifflin, Boston, 1999; https://www.amazon.com/Seizing-Enigma-German-U-Boats-1939-1943/dp/0395427398 .
Books that cover the German and Allied crypto-security problems in more detail are:
* R.A. Ratcliff, “Delusions of Intelligence: Enigma, Ultra, and the end of secure ciphers,” Cambridge Univ. Press, Cambridge, UK, c.2006; https://www.amazon.com/Delusions-Intelligence-Enigma-Secure-Ciphers/dp/0521736625.
* Dermot Turing, “Enigma Traitors: The struggle to lose the cipher war,” The History Press, Gloucestireshire, UK, c. 2023; https://www.amazon.com/Enigma-Traitors-Struggle-Lose-Cipher-ebook/dp/B0CLD5GCHJ.
