'
' a text file encryption and decryption routine created with Rapid-Q
' 5/28/00
' Scott aka Sand Dune
'
$include "rapidq.inc"

declare sub do_it           ' the subroutine "do_it" encrypts and decrypts the text

dim lin$        as string   ' this holds each line of text that we will process
dim kar$        as string   ' this holds each character in a line
dim pass$       as string   ' the password is used to scramble each character in the text
dim new_kar$    as string   ' the new character created when scrambling or unscrambling
dim new_line$   as string   ' the new line created when scrambling or unscrambling
dim mode$       as string   ' a flag to determine whether to encrypt (1) or decrypt (0)
dim line_len#   as integer  ' the length of the line to loop through when processing
dim line_loop#  as integer  ' the line counter when looping thru each character in the line
dim kar#        as integer  ' the ascii equivalent of the character being processed
dim scram#      as integer  ' the modulo remainder used when scrambling eggs (or undoing)
dim pass_len#   as integer  ' the length of the password used in the cryptography formula
'----------------------------------------------------------------------------------------
' assign some text and show it, call the encrypt routine, show it, decrypt it, show it
'
  pass$ = "wrialpliidaqm"   ' password containing "william" and "rapidq" every other letter
  pass_len# = len(pass$)    ' the length of the password that was so cleverly designed

  lin$ = "Scott is called Sand Dune because he lives near the Atlantic Ocean" ' text2encrypt
  ?lin$                     ' show the text before doing anything to it

  mode$ = "1"               ' set the flag for encrypting the data (scramble them eggs)
  do_it                     ' call the subroutine to "do it"
  ?new_line$                ' show the encryption results

  lin$ = new_line$          ' assign the encrypted line to be decrypted
  mode$ = "0"               ' set the flag for decrypting the data (unscramble)
  do_it                     ' call the subroutine to "do it"
  ?new_line$                ' show the decryption results

' the end                   ' normal end of program
'----------------------------------------------------------------------------------------
' the little engine that does the work
'
sub do_it                   ' this subroutine encrypts and decrypts text based on "mode$"
'
  line_len# = len(lin$)                             ' get the length of the line to do
  new_line$ = ""                                    ' initialize a new line to create
  for line_loop# = 1 to line_len#                   ' loop thru each character in line
    kar$ = mid$(lin$, line_loop#, 1)                ' extract individual character
    kar# = asc(kar$)                                ' get ascii value of that character
    scram# = line_loop# mod pass_len#               ' get remainder of pos and pass len
    if mode$ = "1" then                             ' if parameter one is a "1"
      kar# = kar# + asc( mid$(pass$, scram#, 1) )   '   encrypt the character
    else                                            ' or else it is a "0" and we should
      kar# = kar# - asc( mid$(pass$, scram#, 1) )   '   decrypt the character
    end if                                          ' end of 'if parameter is "1"
    new_kar$ = chr$(kar#)                           ' assign the new character
    new_line$ = new_line$ + new_kar$                ' append it to the new output line
  next                                              ' end of loop thru each character
'
end sub
'----------------------------------------------------------------------------------------