Magento 2 - What's the purpose of Formkey Validator?

Question

I want to know what does the formkey validator do : Magento\Framework\Data\Form\FormKey\Validator

Answer 1

Simply and in order :

1. Magento/Framework/Data/Form/FormKey::getFormKey() : generate a formkey.

2. Magento/Framework/Data/Form/FormKey/Validator::validate() validate that formkey.

Exemple : vendor/magento/module-customer/Controller/Account::LoginPost.php

public function execute()
{
    if ($this->session->isLoggedIn() || !$this->formKeyValidator->validate($this->getRequest())) {
        ...
        return $resultRedirect;
    }

Here magento check : if a user is already logged in $this->session->isLoggedIn() or a formkey request is not valide !$this->formKeyValidator->validate($this->getRequest()), it returns and redirects to the previous page.