🚀 go-pugleaf

On Sat, 28 Sep 1996, Scott Earnest wrote:

> > I know of a college who reversed ASCII values for an encryption
> > program. DOES ANYONE KNOW THE CODE TO DO THIS.
>
> Well, depending on what you mean by "reverse", sure.  But why on earth would you
> want to do that if you want encryption?  It's pathetically easy to break.
>
> program this_is_lousy_encryption;
>
> var
>   fi, fo : file of byte;
>   b : byte;
>
> begin
>   assign (fi,'source.dat');
>   assign (fo,'dest.dat');
>   while not eof(fi) do
>     begin
>       read (fi,b);
>       b := 255-b;
>       write (fo,b);
>     end;
>   close (fi);
>   close (fo);
> end.
>
> (Yes, I'm intentionally demoing this in about the slowest way possible.)

I came up with a more interesting <but still useless> XOR routine.  The
program was simple:  The first few bytes of the encrypted file were ENC,
the next two were the major/minor revision, followed by the source file's
original extention.  The rest of the file was the encrypted source.

The encryption was accomplished by asking for a string.  I was in a hurry,
so I just used Readln..  <owch>  Then, I started, byte for byte, reading
the file and XORing it with the next char of the password string.  When
StrOfs > Length (PW) I would reset the offset to 1.


Simple, alomost totally useless, and a perfect A...  hehehehe  The only
thing I DIDN'T do was put in the password checking CRC...  Wow, that would
have increased security and usability, wouldn't it?  <G>

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            V                 KnightBird - knghtbrd@teleport.com