$WEB_SERVER        = "http://your.server.com";
$ABS_PATH          = '/var/www/htdocs';
$FONT_DIRECTORY    = '/usr/share/fonts/default/TrueType';
$HTTP_SECURITY_IMAGE_DIR = $WEB_SERVER . '/images/security';
$ABS_SECURITY_IMAGE_DIR  = $ABS_PATH   . '/images/security';

sub get_secret_word {
    # best way to set up allowed char array dropping i l o I O 0 1 chars
    # these chars look very similar
    my @chars = ( 'a'..'h', 'j', 'k', 'm', 'n', 'p'..'z', 'A'..'H', 'J'..'N', 'P'..'Z', 2..9 );
    my $secret_word = $chars[rand @chars];
    $secret_word .= $chars[rand @chars] for 1..4;
    # generate hash of secret word
    my $secret_word_hash = generate_MD5_hash(lc($secret_word));
    return $secret_word, $secret_word_hash;
}

sub generate_MD5_hash {
    my ( $plain_text ) = @_;
    $plain_text = '' unless defined $plain_text;
    require Digest::MD5;
  return Digest::MD5->new->add( $plain_text . 'Secret=GNUisnotunix' )->hexdigest;
}

sub write_secret_word_image {
    my ( $word, $hash ) = @_;
    # make the dir from the script, silent failure if it already exists
    mkdir $ABS_SECURITY_IMAGE_DIR;
    require GD;
    # add the text string
    $word = join ' ', split //, $word;
    my $font = select_font();

    my $temp_im = new GD::Image();
    my $temp_green = $temp_im->colorAllocate(0,255,0);

    # get bounds
    my @bounds = GD::Image->stringFT( $temp_green, $font, 20.0, 0.0, 0, 0, $word );
    my $x_bound = $bounds[4];
    my $y_bound = abs($bounds[5]);

    my $i_x = $x_bound + 20;
    my $i_y = $y_bound + 20;

    # create a new image
    my $im = new GD::Image($i_x, $i_y);
    my $green = $im->colorAllocate(0,255,0);
    my $black = $im->colorAllocate(0,0,0);

    @bounds = $im->stringFT( $black, $font, 20.0, 0.0, 10, $i_y - 10, $word  );

    open IMG, ">$ABS_SECURITY_IMAGE_DIR/$hash.png" or ui_system_error( "Can't write security image $!\n" );
    # make sure we are writing to a binary stream
    binmode STDOUT;
    binmode IMG;
    # Convert the image to PNG and print it on standard output
    print IMG $im->png;
    close IMG;
    return "$HTTP_SECURITY_IMAGE_DIR/$hash.png", $i_x, $i_y, $x_bound, $y_bound;
}


sub select_font {
    my @fonts =  <$FONT_DIRECTORY/*.ttf>;
    die "No fonts in directory $FONT_DIRECTORY" unless @fonts;
    my @fontlist;
    for my $font (@fonts) {
        push @fontlist, $font unless $font =~ m/star/;
    }
    return $fontlist[rand @fontlist];
}

__END__

cd freetype-2.1.4
./configure
make
make install

cd ../gd-2.0.15
./configure
make
make install

cd GD-x.x
perl Makefile.PL && make && make test && make install