AppController.php

class AppController extends Controller {
	public $components = array(
			'Session',
			'Cookie',
			'Auth' => array(
				'authenticate' => array(
					'Form' => array(
						'userModel' => 'Member',
						'fields' => array('username' => 'pseudo', 'password' => 'password')
					)
				)
			),
			'Security'
		);

	public function beforeFilter() {
		$this->Auth->allow();
	}

login.ctp

<?php echo $this->Session->flash(); ?>
<div class="col-md-4 column">
	<fieldset>
		<legend>Se connecter</legend>
		<?php echo $this->Form->create('Member'); ?>
			<div class="forum-group">
				<?php echo $this->Form->input('pseudo', array('label' => 'Login :', 'class' => 'form-control')); ?>
			</div>	
			<div class="forum-group">
				<?php echo $this->Form->input('password', array('label' => 'Mot de passe :', 'class' => 'form-control')); ?>
			</div>
			<br />
			<div class="group-form">
				<?php echo $this->Form->submit('Me connecter', array('class' => 'btn btn-success')); ?>
			</div>
		<?php echo $this->Form->end(); ?>
	</fieldset>
</div>
	

Members.php(models)

<?php
class Member extends AppModel {

	public $validate = array(
		'pseudo' => array(
			array(
				'rule' => 'alphanumeric',
				'required' => true,
				'allowEmpty' => false,
				'message' => 'Pseudo invalide'
				
			),
			array(
				'rule' => 'isUnique',
				'message' => 'Ce pseudo est déjà pris.'
			)
		),
		'mail' => array(
			array(
				'rule' => 'email',
				'required' => true,
				'allowEmpty' => false,
				'message' => 'Email invalide'
				
			),
			array(
				'rule' => 'isUnique',
				'message' => 'Cet email est déjà pris.'
			)
		),
		'password' => array(
			'rule' => 'notEmpty',
			'allowEmpty' => false,
			'message' => 'Entrez un mot de passe.'
		)
	);
}

MembersConctroller.php

public function login() {
		if($this->request->is('post')) {
			if($this->Auth->login()) {
				$this->Session->setFlash('Connecté', 'success');
			}else{
				$this->Session->setFlash('Pas connecté', 'error');
			}
		}
	}