The Bletchley Park 1944 Cryptographic Dictionary formatted by Tony ...

The Bletchley Park 1944 Cryptographic Dictionary formatted by Tony Sale (c) 2001
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ANAGRAM. v :
1. To rearrange the letters of a transposition cipher (usually by trial
and error) so as to restore the original plain language.
2. (misused for). To decipher any part of a Playfair cipher,
either by utilizing bigram frequencies and a knowledge of the
probable plain text, or by using a previously reconstructed
Playfair square or squares.
3. (misused for). To break any part of a letter-subtractor, esp.
machine-cipher, depth of two or more messages by differencing and
stencil-search or virtual stencil-search.
ANAGRAM KEY :
The natural numbers (i.e. from 1 upwards) of the letters of a
transposition cipher rearranged into the order which these letters
have in the clear text, thus showing how the cipher letters are
anagramed to restore the original plain language. cf. encipher
key.
ANALYSIS :
1. Systematic examination of cipher messages with a view to
discovering e.g. indicators, limitations, or other characteristics
of the system employed which may provide a point of attack or
suggest a method of solution.
2. Systematic examination of a portion of key, esp. of a machine
cipher, aimed at resolving it into its basic components.
3. (in Met.). A message containing a general description of
the weather situation over a large area, e.g. Western Europe,
at a particular time.
ANTI-CRIB, a :
(applied to regulations or methods). Designed to avoid giving
cryptographic cribs.
APERIODIC :
(esp. of machine ciphers and keys). Showing no evidence of
periodic repetition within the length of one message (owing
usually to great length of key period).
ARBITRARY :
(of code-groups, indicators, etc.). Having had a provisional
subtractor taken off; reduced to provisional, not true, figures
or letters. cf. base