Modern cryptanalysis of the Truppenschlüssel. Issue 3 (4th May 2023)

• Record Type: Journal Article
• Authors: Ostwald, Olaf; Weierud, Frode
• Is Part Of: Cryptologia. Volume 47:Issue 3(2023)
• Page Start: 261
• Page End: 281
• Publication Date: 2023-05-04
• Subjects: Ciphertext-only -- cryptanalysis -- Doppelkasten -- Doppelkastenschlüssel -- double boxes -- double Playfair -- field cipher -- German Army -- NI cipher -- radio message -- seriation -- trigram statistics -- Truppenschlüssel -- two-box cipher -- two-square cipher -- unicity distance -- unsolved ciphers; Cryptography -- Periodicals; 652.8
• DOI: 10.1080/01611194.2021.1998810
• Languages: English
• ISSNs: 0161-1194

Abstract

Abstract: Truppenschlüssel (troop cipher) was a manual cipher used by the German Army during World War II. Based on more than a hundred authentic messages that survived the war, a cryptanalysis is performed. The exact encryption procedure is investigated via two plaintext-ciphertext compromises. A specific ciphertext-only breaking tool is developed, utilizing the hill climbing technique. This leads to successful breaks of most of the messages.