File: vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/config/security.xml

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <parameters>
        <parameter key="security.secure_random.class">Symfony\Component\Security\Core\Util\SecureRandom</parameter>
    </parameters>

    <services>
        <!-- Pseudo-Random Number Generator -->
        <service id="security.secure_random" class="%security.secure_random.class%">
            <tag name="monolog.logger" channel="security" />
            <argument>%kernel.cache_dir%/secure_random.seed</argument>
            <argument type="service" id="logger" on-invalid="ignore" />
            <deprecated>The "%service_id%" service is deprecated since Symfony 2.8 and will be removed in 3.0. Use the random_bytes() function instead.</deprecated>
        </service>
    </services>
</container>