Captcha Operation

All CAPTCHA adapters implement Zend\Captcha\AdapterInterface, which looks like the following:

namespace Zend\Captcha;

use Zend\Validator\ValidatorInterface;

interface AdapterInterface extends ValidatorInterface
{
    public function generate();

    public function setName($name);

    public function getName();

    // Get helper name used for rendering this captcha type
    public function getHelperName();
}

The name setter and getter are used to specify and retrieve the CAPTCHA identifier. The most interesting methods are generate() and render(). generate() is used to create the CAPTCHA token. This process typically will store the token in the session so that you may compare against it in subsequent requests. render() is used to render the information that represents the CAPTCHA, be it an image, a figlet, a logic problem, or some other CAPTCHA.

A simple use case might look like the following:

// Originating request:
$captcha = new Zend\Captcha\Figlet(array(
    'name' => 'foo',
    'wordLen' => 6,
    'timeout' => 300,
));

$id = $captcha->generate();

//this will output a Figlet string
echo $captcha->getFiglet()->render($captcha->getWord());


// On a subsequent request:
// Assume a captcha setup as before, with corresponding form fields, the value of $_POST['foo']
// would be key/value array: id => captcha ID, input => captcha value
if ($captcha->isValid($_POST['foo'], $_POST)) {
    // Validated!
}

Note

Under most circumstances, you probably prefer the use of Zend\Captcha functionality combined with the power of the Zend\Form component. For an example on how to use Zend\Form\Element\Captcha, have a look at the Zend\Form Quick Start.