Conference article

The Typex Scare of 1943: How Well Did the British React to a Cypher-Security Scare?

Dermot Turing
Kellogg College, 62 Banbury Road, Oxford OX2 6PN, UK

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Published in: Proceedings of the 2nd International Conference on Historical Cryptology, HistoCrypt 2019, June 23-26, 2019, Mons, Belgium

Linköping Electronic Conference Proceedings 158:4, p. 31-39

NEALT Proceedings Series 37:4, p. 31-39

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Published: 2019-06-12

ISBN: 978-91-7685-087-9

ISSN: 1650-3686 (print), 1650-3740 (online)


The response of German Naval Intelligence, at various points in World War Two, to suspicions that the Enigma cipher had been broken is well known. In 1943 the British were faced with evidence about the possible compromise of the Typex machine, the highest-level communications device in use across their armed forces. This paper compares the response of the British to the Typex scare to the German investigations concerning Enigma.

Reconstructing the story, it seems that the Germans had, in fact, read some Typex messages. Although Allied codebreaking during the war operated on a higher plane than Germany’s, it was inappropriate to assume that the Germans could not do so. Various similarities between the German and British responses emerge: the British were ill-adapted to investigating their own security; they were reluctant to chase down the truth, using arguments to justify their desire to be reassured that all was safe.


Typex German cryptanalysis Security response TICOM


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