Cakephp JWT implement in API

We will follow 4 steps to implement JWT token in API

1. Install a package to encode and decode JWT token
2. Create a public and a private key to verify and for encode JWT token.
3. Change middleware.
4. Update login function.Install a package to encode and decode JWT tokenWe will use below package
  Link : https://github.com/firebase/php-jwt
  To install this package you have to give below composer command
```
composer require firebase/php-jwt
```
  Create a public and a private key to verify and for encode JWT token.
  
  To generate public and private key in project directory we give below commands
```
# generate private key
openssl genrsa -out config/jwt.key 1024
# generate public key
openssl rsa -in config/jwt.key -outform PEM -pubout -out config/jwt.pem
```

Change middleware

public function getAuthenticationService(ServerRequestInterface $request): AuthenticationServiceInterface

{

$service = newAuthenticationService();

$fields = [

IdentifierInterface::CREDENTIAL_USERNAME => 'email',

IdentifierInterface::CREDENTIAL_PASSWORD => 'password'

];

$service->loadIdentifier('Authentication.Password', [

'returnPayload' => false,

'fields' => $fields,

]);

$service->loadAuthenticator('Authentication.Form', [

    'fields' => $fields,

]);

if($request->getParam('prefix') === 'Api'){

  $service->loadIdentifier('Authentication.JwtSubject');

  $service->loadAuthenticator('Authentication.Jwt', [

     'secretKey' => file_get_contents(CONFIG .'/jwt.pem'),

    'algorithm' => 'RS256',

     'returnPayload' => false

    ]);

}else{

$service->setConfig([

'unauthenticatedRedirect' => Router::url('/login'),

'queryParam' => 'redirect',

]);

$service->loadAuthenticator('Authentication.Session');

}

return$service;

}

Changing login method :

public function login()

{

$result = $this->Authentication->getResult();

if( $result->isValid() )

{

$user = $result->getData();

$privateKey = file_get_contents(CONFIG .'/jwt.key');

$payload = [

'sub' => $user->id,

'exp' => time()+60

];

$user = [

'token' => JWT::encode($payload,$privateKey,'RS256'),

'userEnt' => $user

];

}else{

$this->response = $this->response->withStatus(401);

$user = [

'message' => 'invalid user'

];

}

$this->set('user',$user);

$this->viewBuilder()->setOption('serialize','user');

}

That’s it.