Dealing with cookies from outside Prestashop within controllers

[Mounowicz]

In our Prestashop 1.6 module, we need to access a cookie that comes from an external tracking code, i.e., a cookie not created inside Prestashop. If I access it through the standard PHP global $_COOKIE, everything works fine; however, such a code does not pass through the Prestashop validator.
If I am trying to retrieve the cookie using $this->context->cookie->get, I don't get anything, because Prestashop encrypts cookies internally.
Is there any valid solution, how to get to external cookie data?
Thanks.