Drupal 8 - Cannot open source device in random_bytes() + core/lib/Drupal/Component/Utility/Crypt.php

I've problem to install Drupal 8.1.3 in my Mac OSX El captain :

My development environment :

PHP v7.0.9, 
Zend Server

Problem :

The website encountered an unexpected error. Please try again later. Exception: Cannot open source device in random_bytes() (line 31 of core/lib/Drupal/Component/Utility/Crypt.php).

It would be highly appreciated if someone can point me in the right direction.