The 1944 Bletchley Park Cryptographic Dictionary
Codes and Ciphers
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BOOK KRAC :
BOOLEAN ADDITION :
BOX, n :
2. A cage in transposition systems.
3. (in Enigma). A cipher alphabet so arranged and if necessary so divided into compartments that when one of the components is slid on one position (cyclically in each compartment) a second cipher alphabet is produced.
BOX, v :
2. To establish the plain language equivalents of the groups of (a code-book).
3. (machine ciphers). To decipher simultaneously (two or more messages known to be in depth) by finding, usually by trial and error, key-letters which make reasonable sense of both or all the messages; to read (a depth).
4. To resolve (a length of key obtained by the above means) into its basic, short-period, components by analysis; to establish thus the essential structure and method of operation of (a cipher machine).
5. To reduce (any type of cipher) to plain language; to reconstruct (any cipher system).
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