ApiAuthenticator.php

<?php

namespace App\Authentication\Authenticator;

use ArrayAccess;
use Authentication\Authenticator\FormAuthenticator;
use Authentication\Authenticator\Result;
use Authentication\Identifier\IdentifierInterface;
use Cake\Utility\Security;
use Firebase\JWT\JWT;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use RuntimeException;

/**
 * Class ApiAuthenticator
 * @package App\Authentication\Authenticator
 */
class ApiAuthenticator extends FormAuthenticator
{
    protected $_defaultConfig = [
        'loginUrl' => null,
        'urlChecker' => 'Authentication.Default',
        'fields' => [
            IdentifierInterface::CREDENTIAL_USERNAME => 'username',
            IdentifierInterface::CREDENTIAL_PASSWORD => 'password'
        ],
        'algorithm' => 'HS256',
        'secretKey' => null,
    ];

    /**
     * JsonAuthenticator constructor.
     * @param IdentifierInterface $identifier
     * @param array $config
     */
    public function __construct(IdentifierInterface $identifier, array $config = [])
    {
        parent::__construct($identifier, $config);

        if (empty($this->_config['secretKey'])) {
            if (!class_exists(Security::class)) {
                throw new RuntimeException('You must set the `secretKey` config key for API authentication.');
            }
            $this->setConfig('secretKey', Security::getSalt());
        }
    }

    public function authenticate(ServerRequestInterface $request, ResponseInterface $response)
    {
        $result = parent::authenticate($request, $response);
        return $result->isValid()
            ? new Result($this->buildData($result->getData()), Result::SUCCESS)
            : $result;
    }

    /**
     * @param null|array|ArrayAccess $data The identity data
     * @return array
     */
    protected function buildData($data)
    {
        $jwt = $this->buildJwt($data);

        return [
            'jwt' => $jwt,
            'id' => $data->id
        ];
    }

    /**
     * @param null|array|ArrayAccess $data The identity data
     * @return string
     */
    protected function buildJwt($data)
    {
        return JWT::encode([
            'sub' => $data->id,
        ],
            $this->getConfig('secretKey'),
            $this->getConfig('algorithm')
        );
    }
}