CRYPTAID
                         A CRYPTANALYSIS HELPER
                                  by
                            David Lovelock

    This program is designed to aid in the decoding of simple substitution
aristocrat ciphers, i.e. each letter in the original message is replaced
throughout by a unique cipher letter code, while punctuation and spaces are
unchanged.  An excellent introduction to cryptanalysis in general and
aristocrats in particular, can be found in CRYPTANALYSIS FOR MICROCOMPUTERS
by Caxton C. Foster, (Hayden Book Co., 1982, Chapters 7 and 8, about $15).

    The programs supplied here are as follows:

CRYPTAID.EXE  - the main program.
02N.DCT and 02P.DCT  \
03N.DCT and 03P.DCT   \
            ...       /   - dictionary files.
18N.DCT and 18P.DCT  /

    They should all be on the same floppy, or all in the same sub-directory on
a hard drive.  Obviously everything runs faster if a hard drive is available.

    Before using the program CRYPTAID, enter the message to be decoded in a
standard, unformatted, ASCII text file and  save it in the same directory as
CRYPTAID and all its supporting programs.  Let's assume you have saved the file
under the name "MESSAGE".  To invoke the deciphering aid, type

CRYPTAID MESSAGE

    CRYPTAID will now load and display a title screen while it reads and
analyses the file MESSAGE.  While reading, CRYPTAID does a number of
things.
It counts the number of occurrences of each letter of the alphabet in the
entire text.
It counts the number of occurrences of each letter of the alphabet which
starts a word.
It counts the number of occurrences of each letter of the alphabet which
ends a word.
It counts the number of occurrences of each letter of the alphabet as a
single letter word.
It does a consonant line analysis, suggesting which letters might be
vowels, and which consonants.

    When it has read the entire text the main screen appears, divided into four
sections.

    The top section initially contains the upper case alphabet corresponding to
the CIPHER text, with a blank line corresponding to the PLAIN text translation
table below it.  Below that there is a lower case alphabet corresponding to the
PLAIN text, followed by a blank line for the CIPHER code table.  When a guess
is made these blank lines will automatically display the translation table.
Displaying the two way translation table is particularly useful if the
code-maker has used a keyword as the basis of the cipher.  The convention
adopted here, upper case for CIPHER text, and lower case for PLAIN text (the
translation) is used throughout.

    The second section displays up to six lines, 468 characters, of the file
MESSAGE, in upper case.  Below each line is another line of characters,
initially blank, which holds the translation of the letter directly above
it.  It will be in lower case.  Word wrap is in effect, so a word will not be
split between two lines.

    The third section gives the title of the cipher file and the choice of
commands, while the fourth is the message area, which initially awaits you
command.

    Although this is designed to help solve aristocrats, it can also be used
to create them.  Enter the plain text as though it were a cipher, and the
encode it by selecting the translation, finally saving the encoded message in
the SOLUTION.SLN file.