# CipherTextI.pm
#
# Charles Prichard 6-16-01
#

#
#################################################
package CipherTextI;

use strict;
use integer;
use bytes;
#################################################
#   PUBLIC Subroutine                           #
#################################################
sub new($) {
	
my $class = shift;

	my $self = {};
	
	bless $self, ref $class || $class;


	$self->{xString} = undef;
	$self->{xStr} = undef;

	$self->{R_KEY} = undef;
	$self->{ATT} = undef;
	$self->{S_KEY} = undef;
	$self->{cipher_key} = undef;
	
	$self->{RSORT} = [];
	
	$self->init(@_);
	
	return $self;

}
sub init($){
	
	my $self = shift;
	
	my ($params) = shift;
	
	my @temp1 = split /\;/, $params;
    
    	my %params = ();
    
    	my @temp2=();
    
    	foreach my $x (@temp1){
    
    		@temp2 = split /\=/, $x;
    
    		$self->{$temp2[0]} = $temp2[1];
   	}
	
	$self->{RSORT} = [3,28,7,5,39,62,34,32,56,18,17,6,29,49,63,45,13,13,29,40,2,17,17,9,12,61,56,23,55,37,31,13,27,52,8,23,38,53,9,60,31,30,39,27,37,14,14,34,8,29,58,10,25,3,19,37,11,35,52,39,48,24,22,19];
    
	$self->{S_KEY} = $self->Make_shiftedKeys();
	
	return;
}
#################################################
#   PUBLIC Subroutine                           #
#################################################
sub encipher($) {
	
	my $self = shift;
    	
	my $MSG = shift;;
        
	$MSG = $self->Encode($self->Encode($MSG,$self->{R_KEY}),$self->{S_KEY});	

	return $MSG;     
}
#################################################
#   PUBLIC Subroutine                           #
#################################################
sub decipher {
	
	my $self = shift;
    	
	my $MSG = shift;;
  	 
	$MSG = $self->Decode($self->Decode($MSG,$self->{S_KEY}),$self->{R_KEY});
  	
	return $MSG;     
}
#################################################
#       PRIVATE Subroutine                      #
#################################################
sub Make_shiftedKeys(){
	
	my $self = shift;
	
	my $shift = $self->setAttribute();
	
	$self->{S_KEY} = $self->modifyKeys();

	if (($shift % 2) == 1){$self->{S_KEY} = (substr($self->{S_KEY},1,(length $self->{S_KEY})));}
	
	else {$self->{S_KEY} = (substr($self->{S_KEY},0,(length $self->{S_KEY}) - 1));}

	my $key;
	my $v;
	
	for (my $i=0; $i <= ($shift - 1) % length $self->{S_KEY}; $i++){             
        	
        	my $key = substr($self->{S_KEY},0,1);
        	
        	$v = ord($key) - 32;
        	
        	$self->{S_KEY} = (substr($self->{S_KEY},1,(length $self->{S_KEY}) - 1));

        	$self->{S_KEY} .= chr($v ^ $self->{RSORT}[$v] + 32);
	
        }
        
        return $self->{S_KEY};
}
#################################################
#       PRIVATE Subroutine                      #
#################################################  
sub setAttribute(){
	
	my $self = shift;
	
        $self->{ATT} = 0x00;
        
        for (my $i=0; $i < (length $self->{R_KEY}); $i++){
	
		$self->{ATT} = $self->{ATT} ^ (ord(substr($self->{R_KEY},$i,1)) - 0x20);  
  	} 
        
        return $self->{ATT};
}
#################################################
#       PRIVATE Subroutine                      #
#################################################
sub modifyKeys(){
	
	my $self = shift;
	my S_KEY = "";
	my $i, $x;
    
    For $x = 1 To length($self->{R_KEY})
    
        $i = ord(substr($self->{R_KEY}, $x, 1)) - 32
        
        S_KEY = S_KEY + Chr(($i ^ $self->{RSORT}[$i] ^ $self->{ATT}) + 32)
    
    Next x
	
	return S_KEY;

}
#################################################
#       PRIVATE Subroutine                      #
#################################################
sub Encode($$){
	
	my $self = shift;
    
        $self->{xString} = shift;
    
        $self->{cipher_key} = shift;
    
        $self->cipher();
    
        return $self->{xStr};

}
#################################################
#       PRIVATE Subroutine                      #
#################################################
sub Decode($$){
	
	my $self = shift;
	
	$self->{xString} = shift;
    
        $self->{cipher_key} = shift;
    
        $self->cipher();
    
        return $self->{xStr};

}
#################################################
#       PRIVATE Subroutine                      #
#################################################
sub cipher(){
	
	my $self = shift;

        $self->{xStr} = "";
     
        my $keyval;
     
        my $xch;
     
        my @akeys = split "",$self->{cipher_key};
     
        my $keylen = length $self->{cipher_key};
     
        my $i = (length $self->{xString} % $keylen); # DATA DEPENDENT SHIFT 
    
        for(my $x=0; $x < length ($self->{xString}); $x++){
        	
      		$keyval = ord($akeys[$i]) - 0x20;
      	    
      		$xch = ord(substr($self->{xString},$x,1));
      		
      		if ($xch > 0x7f){ $xch = $xch - 0x21;}
      	    
        	if ($xch > 0x1f){
            	

         		$xch = ($keyval ^ ($xch - 0x20)) + 0x20; # Apply cipher
         	  
         		
      		}
         	
         	if ($xch > 0x7f){ $xch = $xch + 0x21;}
		
		$self->{xStr} .= chr($xch);                           
     
        	$i++;
     
        	if ($i == $keylen){$i = 0;}
     
        }         

        return;
}

1;