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POwhats wrong with this php script? (captcha)
 

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  1. POwhats wrong with this php script? (captcha)
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    <p>I am trying to add a simple captcha to an hml form. Code is originally from <a href="http://www.encaps.net/software/php-captcha/" rel="nofollow">here</a></p> <p>here is the PHP script that generates the image and stores the captcha variable:</p> <pre><code>&lt;?php session_start(); header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); header("Cache-Control: no-store, no-cache, must-revalidate"); header("Cache-Control: post-check=0, pre-check=0", false); header("Pragma: no-cache"); function _generateRandom($length=6) { $_rand_src = array( array(48,57) //digits , array(97,122) //lowercase chars // , array(65,90) //uppercase chars ); srand ((double) microtime() * 1000000); $random_string = ""; for($i=0;$i&lt;$length;$i++){ $i1=rand(0,sizeof($_rand_src)-1); $random_string .= chr(rand($_rand_src[$i1][0],$_rand_src[$i1][1])); } return $random_string; } $im = @imagecreatefromjpeg("captcha.jpg"); $rand = _generateRandom(3); $_SESSION['captcha'] = $rand; ImageString($im, 5, 2, 2, $rand[0]." ".$rand[1]." ".$rand[2]." ", ImageColorAllocate ($im, 0, 0, 0)); $rand = _generateRandom(3); ImageString($im, 5, 2, 2, " ".$rand[0]." ".$rand[1]." ".$rand[2], ImageColorAllocate ($im, 255, 0, 0)); Header ('Content-type: image/jpeg'); imagejpeg($im,NULL,100); ImageDestroy($im); ?&gt; </code></pre> <p>here is the script that validates the entered captcha:</p> <pre><code>&lt;?php if($_SESSION["captcha"]==$_POST["captcha"]) { //CAPTHCA is valid; proceed the message: save to database, send by e-mail ... echo 'CAPTHCA is valid; proceed the message'; } else { echo 'CAPTHCA is not valid; ignore submission'; } ?&gt; </code></pre> <p>Problem is that the session seems to be storing only 3 chars, so the values never match - since the generated image has 6 chars.</p> <p>The code above is a bit strange (I must admit I am not used the image library API). But I dont know why we call _generateRandom() with arg value of 3, and also, why imagestring is being called twice ???</p>
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    1. USoompahloompah
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    1. COSkimming quickly you should use `_generateRandom();` once. Don't provide arguments if you want the length to be 6 because that is already standard argument. It seems like you are doing a bunch of double function calls.
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      1. POwhats wrong with this php script? (captcha)
      1. USAlfred
    2. COI think I may have spotted the problem. The value being stored is incorrect. The displayed value in the image is a combination of the chars returned from generateRandom(). It is this combined value that needs to be stored in the session variable. I am investigating further to see if there is some random selection of chars...
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      1. USoompahloompah
    3. COWhy do you have alternate blank lines?
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      1. USLightness Races in Orbit
 

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