Security Image

<?php
	ob_start();
	session_start();
	
	$width = 160;
	$height = 16;
	$fontsize = 3.5;
	
	for($i = 0; $i < 3; $i++)
	{
		unset($numer);
			$number = rand(1, 9);
		
		switch($number)
		{
		    case 1: 
				$written = " One";
					 break;
					 
		    case 2: 
				$written = " Two"; 
					break;
		  
		    case 3: 
				$written = " Three"; 
					break;
		    
			case 4: 
				$written = " Four"; 
					break;
		    
			case 5: 
				$written = " Five"; 
					break;
		   
		    case 6: 
				$written = " Six"; 
					break;
		   
		    case 7: 
				$written = " Seven"; 
					break;
		    
			case 8: 
				$written = " Eight"; 
					break;
		    
			case 9: 
				$written = " Nine"; 
					break;
		}
		
		$totalnumbers .= $number;
		$totalwritten .= $written;
	}
	
	$_SESSION['hash'] = md5($totalnumbers);
		
	$fontwidth = ImageFontWidth($fontsize) * strlen($totalwritten);
	$fontheight = ImageFontHeight($fontsize);	

	$img = ImageCreate($width, $height);
	$background = ImageColorAllocate($img, 97, 96, 78); 
	$textcolor = ImageColorAllocate($img, 0, 0, 0);			
	
	ImageFill($img, 1, 1, $background);
	imagestring($img, $fontsize, rand(3, $width-$fontwidth-3), rand(2, $height-$fontheight-3), $totalwritten, $textcolor);
	
	header('Content-type: image/png');
	ImagePNG($img); 
	ImageDestroy($img); 
?>

<?php
	ob_start();
	session_start();
 
	$width = 160;
	$height = 16;
	$fontsize = 3.5;
 
	for($i = 0; $i < 3; $i++)
	{
		unset($numer);
			$number = rand(1, 9);
 
		switch($number)
		{
		    case 1: 
				$written = " One";
					 break;
 
		    case 2: 
				$written = " Two"; 
					break;
 
		    case 3: 
				$written = " Three"; 
					break;
 
			case 4: 
				$written = " Four"; 
					break;
 
			case 5: 
				$written = " Five"; 
					break;
 
		    case 6: 
				$written = " Six"; 
					break;
 
		    case 7: 
				$written = " Seven"; 
					break;
 
			case 8: 
				$written = " Eight"; 
					break;
 
			case 9: 
				$written = " Nine"; 
					break;
		}
 
		$totalnumbers .= $number;
		$totalwritten .= $written;
	}
 
	$_SESSION['hash'] = md5($totalnumbers);
 
	$fontwidth = ImageFontWidth($fontsize) * strlen($totalwritten);
	$fontheight = ImageFontHeight($fontsize);	
 
	$img = ImageCreate($width, $height);
	$background = ImageColorAllocate($img, 97, 96, 78); 
	$textcolor = ImageColorAllocate($img, 0, 0, 0);			
 
	ImageFill($img, 1, 1, $background);
	imagestring($img, $fontsize, rand(3, $width-$fontwidth-3), rand(2, $height-$fontheight-3), $totalwritten, $textcolor);
 
	header('Content-type: image/png');
	ImagePNG($img); 
	ImageDestroy($img); 
?>