Recent Progress With Enigma Cryptanalysis

George Lasry

The Enigmas have been the subject of extensive cryptanalytic research by Polish, British, US, and German cryptographers before and during WW II. A series of ingenious techniques were developed, for the recovery of the rotor wiring and of key settings, for various models and operational scenarios. This included attacks against the pre-war so-called 'doubled indicators' and the Turing Bombe, that implements a highly effective known-plaintext attack. While the story about WW II codebreaking of Enigma became public in the 1970s, very little was known about post-war codebreaking efforts against Enigma, until 1995, when Jim Gillogly published a groundbreaking paper with a modern ciphertext-only attack. While not practical for real-life messages, Gillogly's techniques paved the way for further advances and the successful decipherment of original WW II cryptograms. Recently, those ciphertext-only techniques have been further perfected, and the original primarily mathematical Polish methods revisited and significantly improved. Dr. George Lasry will present the evolution of modern cryptanalysis of Enigma, including results from his own research, starting with some technical and historical background. He will cover modern techniques for recovering rotor wiring, improved attacks against double indicators, novel statistical ciphertext-only attacks, as well as software-based enhanced implementations of the original Turing Bombe. Those state-of-the-art techniques are being implemented in the open-source CrypTool 2 platform, and several of them will be demonstrated.