I am also following what this guy's asking storage of client credential on OAuth2 server about oauth2-server-php-docs. Although it answered one thing for the client secret, I wanna ask about the users credentials. Check the following code sample from oauth2-server-php-docs:
// create some users in memory
$users = array('bshaffer' => array('password' => 'brent123', 'first_name' => 'Brent', 'last_name' => 'Shaffer'));
// create a storage object
$storage = new OAuth2\Storage\Memory(array('user_credentials' => $users));
// create the grant type
$grantType = new OAuth2\GrantType\UserCredentials($storage);
// add the grant type to your OAuth server
$server->addGrantType($grantType);
It says that the user credentials will be stored in memory and that it doesn't say anything about password encryption. This is my use case -- I already have user credentials stored in MySQL with password encrypted using PHP password_hash(). So how can I match or use the line $storage = new OAuth2\Storage\Memory() if the $user['bshaffer']['password'] is just a plain text?