Action This Day edited by Michael Smith and Ralph Erskine, Bantam, 拢25,
ISBN 0593049101
WHAT made Hitler鈥檚 lieutenants so certain the Enigma codes were unbreakable?
Despite suspicious submarine and shipping losses that pointed to a breach of the
message enciphering system, the Nazis carried on regardless. To anyone who has
ever wondered why鈥攁nd it is surely one of the most baffling episodes in
cryptographic history鈥攐ne essay in this compelling compilation finally
offers up some answers.
In Action This Day (named after the label on Winston Churchill鈥檚
memo that gave Alan Turing and colleagues all possible resources) the editors
have assembled 22 essays that chronicle the journey from the initial breaking of
Enigma by the Polish Cipher Bureau to the birth at Bletchley Park of the
electronic codebreaking computers that ran the world鈥檚 first hard-wired (rather
than stored) programs. Bletchley veterans and historians describe
cryptanalytical breakthroughs, peppered with priceless anecdotal and technical
detail.
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But it鈥檚 the essay on what the Germans knew about Enigma鈥檚 dodgy security
that astonished me. Erskine shows that plenty of German officers were worried
that Enigma was being read routinely. Even Admiral D枚nitz, commander of the
U-boat fleet, wondered how British subs managed to ambush U-boats in remote
parts of obscure coasts鈥攗nless someone was able to read their ciphers.
Erskine relates how the German investigations were scuppered by people who
simply could not countenance a breach of Enigma. It seems bizarre when you
consider that they knew the Poles had broken it well before the Second World
War. Fascinating stuff.