Text_CAPTCHA_Numeral

Implementation of mathematic operation CAPTCHAs (Completely Automated Public Turing tests to tell Computers and Humans Apart).

Introduction

This package provides the functionality to create Numeral CAPTCHAs (Completely Automated Public Turing tests to tell Computers and Humans Apart). Features include:

The package creates numeral CAPTCHAs; due to the stateless nature of the HTTP protocol, the logic to secure a webpage using the package must be specifically implemented. See the usage example for detailled information.

Currently

Example

The following example implements the standard use of a CAPTCHA: Submitted form data is only evaluated when a CAPTCHA has been solved correctly.

Example 60-3. Creating a Numeral CAPTCHA

This example is just to show you how to generate a simple mathematic operation with Text_CAPTCHA_Numeral.

require_once 'Text/CAPTCHA/Numeral.php';
$num       = new Text_CAPTCHA_Numeral;
$operation = $num->getOperation();

/**
 * This will print the mathematical operation
 * that has been generated by the package.
 */
print $operation;

Example 60-4. Securing a form with a Numeral CAPTCHA

This example will show you how to secure a form using the numeral captcha. It takes generates an operation and store it's result into a session variable

require_once 'Text/CAPTCHA/Numeral.php';
$numcap = new Text_CAPTCHA_Numeral;

if (isset($_POST['captcha']) && isset($_SESSION['answer'])) {
    if ($_POST['captcha'] == $_SESSION['answer']) {
        $errors[] = 'Ok.. YOu might be human..';
    } else {
        $errors[] = 'You are or not human or dumb';
    }
}
    if (!empty($errors)) {
        foreach ($errors as $error) {
            print "<h1><font color='red'>$error</font></h1><br />";
        }
    }


    print '
        <form name="capter" action="index.php?page=liveExample" method="post">
         <table>
          <tr>
           <th>What is this result pilgrim?: '.$numcap->getOperation().'</th>
           <td><input type="text" value="" name="captcha" /></td>
          </tr>
          <tr>
           <th/>
           <td><input type="submit" value="Let me prove you that I am human!" /></td>
          </tr>
        </form>
    ';
    $_SESSION['answer'] = $numcap->getAnswer();