- 12 -
(continued)
As the shape is completely determined by the key-length and the
number of letters in the message the recipient, knowing the key, can
reconstruct the cage, and the cryptographer, knowing only the
number of letters, can make tentative cages for different assumed
key-lengths.
2. A Playfair square.
CALL SIGN :
A group usually of three or more letters and/or figures, sent
either in clear or in cipher, either in the preamble or in the
body of a message, and serving to identify the sender and/or the
recipient; a code name.
CARRY :
1. To represent or convey.
2. (in addition, etc: see carrying)
CARRYING :
Belonging to or obtained in conformity with the rules of normal
adding and subtracting (whereby 9 + 7 = 16, 33 - 18 = 15), as
opposed to normal cryptographic addition and subtracting (whereby
9 + 7 = 6, 33 - 18 = 25), which is non-carrying.
CATALOGUE :
(especially). A tabulated record of all the immediately relevant
consequences or implications of each of a complete set of
hypotheses in a consultable form.
CENTIBAN :
A scoring unit for probabilities equal to one-hundredth of the true
scoring unit, enabling decimal fractions to be expressed more
conveniently as whole numbers. The true score (i.e. the logarithm
of the probability of a particular occurrence) multiplied by one
hundred is the score expressed in centibans, cf. deciban.
CHAIN :
1. (in double Playfair). A series of non-reversible bigram
equations such that the clear bigram of one equation is the
reverse of the cipher bigram in the previous. From such a
series it can be inferred that the letters forming every second
bigram (either of the clear bigrams or of the cipher) occur in
the same line in their respective squares, and are evenly
spaced along that line.
2. (especially in Enigma). A connected series of constatations
forming a menu or part of a menu; also, a set of consequences
obtained from one stecker assumption.
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