[Cryptography] On improving the performance of the classical Playfair cipher
mok-kong shen
mok-kong.shen at t-online.de
Thu Apr 7 07:04:47 EDT 2016
[Addendum:] We note incidentally that, since Playfair is a substitution,
it is generally profitable, if desired, to combine the
scheme with transpositions, e.g. the common columnar transposition or
preferrably its variant of the RS44-type, as pre-prosessing and/or
post-processing.
(An RS44-type of transposition can be conveniently specified either via
the matrix of a certain crossword puzzle in a newspaper or journal or
via filling a matrix with a certain natural language sentence and
choosing to have the locations of certain alphabetical characters as
black squares such that there would roughly be a certain desired
percentage of rather randomly distributed squares of the matrix that
are black.)
M. K. Shen
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