CRYPT.100     Documentation
===========================

c1987 by Jon Diercks [73327,2353]

CRYPT.100 is a machine language text file encoder/decoder for the Model 100.

* It scrambles 7-bit ASCII text based on a keyword of any length.

* It modifies the text file in place in the M100 menu, without creating a
second file.  This theoretically allows for coding of RAM files of up to
almost 32K!

* It ignores all spaces, carriage returns, control characters and 8-bit
data, including any spaces or CR's added after encryption.  <This facilitates
EasyPlex transmission of encrypted files.>

* Best of all, it's FAST.  No more waiting for a slow BASIC coder to putz
along and crank out the correct file.  For most small files, you won't know
what hit you - coding seems almost instantaneous.


INSTRUCTIONS:

Loading:  Download CRYPT.LDR from this DL and load it into BASIC.  CRYPT.LDR
is a relocating loader <created with BASBLD.PW3 in DL8> so if you want to
put CRYPT under another ML program, figure out where you want it.
Otherwise, CLEAR 256,MAXRAM and run CRYPT.LDR.  Just hit <enter> for the
end address prompt and CRYPT will be loaded just below maxram.  CRYPT.CO
will appear in the menu.

Running:  As long as memory is clear, CRYPT.CO can be executed from the menu
or RUNMed.  The files will be listed, and you will be prompted for the file
to work on.  You must include the .DO extension.  Next, type the keyword you
wish to use to scramble or unscramble your text.  The keyword must all be
alpha characters - CRYPT ignores whether they are upper or lower case.
Finally, you must select <E>ncrypt or <D>ecrypt mode.  As soon as CRYPT is
done, you are returned to the M100 Menu <or BASIC, if that's where CRYPT was
called from>.  Simplicity itself!

Tips:  For total security, here's a few practices to follow.

* Don't use special "cute" things in your file, like lines of dashes or
equal signs or an asterisk at the beginning of each paragraph - they make
it easy to find a pattern.  Keep the amount of text to a minimum.  Long
files are easier to crack than short ones.

* Spaces make it easier to decipher a coded file, soifyouwantyoucantakeallthe
spacesoutlikethis, orjust takeso meofthe spaces outandmove themaround.

* If you want to get really complicated, encode the file *twice* with two
keywords of _different_ lengths.  It doesn't matter what order, i.e. if you
encode first with 'abc' then with 'wxyz', you can decode with either
'abc' or 'wxyz' first, as long as you do both.  The effect is as if you encoded
with a very long keyword, making it hard to detect a pattern.

* _DON'T_ use keywords like 'abc' or anything less than three letters.

* _DON'T_ insert or delete any *codeable* characters to the file after it's
been coded.  CRYPT will ignore spaces, CR's and control characters, but any
letters or numbers will screw up the code.

One final note:  There is a bug somewhere in one of the ROM routines
that causes an error with certain filenames <Seems to happen most when
filename is part of another filename in the menu, i.e., CRYPT may not accept
FILEA.DO if there is another file called FILE.DO in the menu at the same time>.
If CRYPT rejects a filename, rename the file and try again.  If anyone figures
out what causes this bug, please let me know.

I hope you make good use of all this.

EasyPlex any questions, comments, suggestions, etc. etc. to:

Jon Diercks [73327,2353]