lithium\template\helper\Security::sign()

public method

Binds the Security helper to the Form helper to create a signature used to secure form fields against tampering.

First FormSignature must be provided with a secret unique to your app. This is best done in the bootstrap process. The secret key should be a random lengthy string.

use lithium\security\validation\FormSignature;
FormSignature::config(['secret' => 'a long secret key']);

In the view call the sign() method before creating the form.

<?php $this->security->sign(); ?>
<?=$this->form->create(...); ?>
    // Form fields...
<?=$this->form->end(); ?>

In the corresponding controller action verify the signature.

if ($this->request->is('post') && !FormSignature::check($this->request)) {
    // The key didn't match, meaning the request has been tampered with.
}

Calling this method before a form is created adds two additional options to the $options parameter in all form inputs:

  • 'locked' boolean: If true, locks the value specified in the field when the field is generated, such that tampering with the value will invalidate the signature. Defaults to true for hidden fields, and false for all other form inputs.

  • 'exclude' boolean: If true, this field and all subfields of the same name will be excluded from the signature calculation. This is useful in situations where fields may be added dynamically on the client side. Defaults to false.

Parameters

  • object $form

    Optional. Allows specifying an instance of the Form helper manually.

Returns

void

Source

	public function sign($form = null) {
		$form = $form ?: $this->_context->form;

		if (isset($state[spl_object_hash($form)])) {
			return;
		}

		Filters::apply($form, 'create', function($params, $next) use ($form) {
			$this->_state[spl_object_hash($form)] = [
				'fields' => [],
				'locked' => [],
				'excluded' => []
			];
			return $next($params);
		});

		Filters::apply($form, 'end', function($params, $next) use ($form) {
			$id = spl_object_hash($form);

			if (!$this->_state[$id]) {
				return $next($params);
			}
			$formSignature = $this->_classes['formSignature'];

			$value = $formSignature::key($this->_state[$id]);
			echo $form->hidden('security.signature', compact('value'));

			$this->_state[$id] = [];
			return $next($params);
		});

		Filters::apply($form, '_defaults', function($params, $next) use ($form) {
			$defaults = [
				'locked' => ($params['method'] === 'hidden' && $params['name'] !== '_method'),
				'exclude' => $params['name'] === '_method'
			];
			$options = $params['options'];

			$options += $defaults;
			$params['options'] = array_diff_key($options, $defaults);
			$result = $next($params);

			if ($params['method'] === 'label') {
				return $result;
			}
			$value = isset($params['options']['value']) ? $params['options']['value'] : "";

			$type = [
				$options['exclude']  => 'excluded',
				!$options['exclude'] => 'fields',
				$options['locked']   => 'locked'
			];
			if (!$name = preg_replace('/(\.\d+)+$/', '', $params['name'] ?? '')) {
				return $result;
			}
			$this->_state[spl_object_hash($form)][$type[true]][$name] = $value;
			return $result;
		});
	}