Hello, here is the code.

#/usr/bin/perl -w
# Demo Version -
# AY2012/2013 ST2614 Assignment
# PM to support Personal Password Manager
package ST2614 ;
our $VERSION = 1.0;
sub getAscii {
    # This is a helper function to support encode() and decode()
    #
      #input a normal string    
      # convert each char of the string to its corresponding ascii cod
+e
      # return the list of the ascii codes
    # in one , delimited string
      my $plaintext= shift;
    my @asciilist = (); 
    my @tmplist = split('', $plaintext);
    foreach $ch (@tmplist) {
        push (@asciilist, ord($ch)); # use ord to get ascii code
    }
    return join(",",@asciilist);
}
sub encode {
  # simple xor encoding
  # Argument 1 - A string in plain text - to be encoded
  # Argument 2 - A string in plain text, represent the key
  # return the xor result in ascii form 
  my ($text , $key) = @_;
  $text = getAscii($text);
  $key = getAscii($key);
  my @textlist = split(',',$text);
  my @keyblk = split(',',$key);
  my $index = 0;
  my $max = @keyblk;
  my @encodedlist = ();
   foreach $chcode (@textlist) {
    # simple xor encoding
    # must use int() to force a numeric xor operation
        my $secret =  int($chcode) ^ int($keyblk[$index]);
        push(@encodedlist,$secret); # store the result 
        # recycle the key block
        $index = ($index+1) % $max; 
   }
    return join(",",@encodedlist);
}
sub decode {
  # simple xor decoding
  # Argument 1 - encoded string in ascii list form 
  # Argument 2 - A string in plain text, represent the key
  # return the xor result in plain text string  form
   my ($secret , $key) = @_;
   $key = getAscii($key);
   # break the line into array and xor with the keyblock
   my @secretlist = split(',',$secret);
   my @keyblk = split(',',$key);

   my $index = 0;
   my $max = @keyblk;
   my $orgText = "";
   foreach $chcode (@secretlist) {
        my $org =  int($chcode) ^ int($keyblk[$index++]);
        # convert numeric ascii value back to character form
        # and append it to $orgText
        $orgText .= chr($org);
        $index = $index % $max; 
   }
   return $orgText;

}
1; # required to return 1 at the end of a pm file
[download]

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