Modern cryptanalysis of the Truppenschlüssel

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 ci...

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Bibliographic Details
Published inCryptologia Vol. 47; no. 3; pp. 261 - 281
Main Authors Ostwald, Olaf, Weierud, Frode
Format Journal Article
LanguageEnglish
Published West Point Taylor & Francis 04.05.2023
Taylor & Francis Inc
Subjects
Algorithms
Ciphertext-only
cryptanalysis
Cryptography
Doppelkasten
Doppelkastenschlüssel
double boxes
double Playfair
Encryption
field cipher
German Army
Messages
NI cipher
radio message
seriation
trigram statistics
Truppenschlüssel
two-box cipher
two-square cipher
unicity distance
unsolved ciphers
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Summary: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.
ISSN:0161-1194
1558-1586
DOI:10.1080/01611194.2021.1998810