app/code/community/Nexcessnet/Turpentine/Model/Core/Session.php
public function getFormKey()
    {
        if (Mage::registry('replace_form_key') &&
                ! Mage::app()->getRequest()->getParam('form_key', false)) {
            // flag request for ESI processing
            Mage::register('turpentine_esi_flag', true, true);
            return '{{form_key_esi_placeholder}}';
        } else {
            return parent::getFormKey();
        }
    }
public function getFormKey()
    {
        if (Mage::registry('replace_form_key') &&
                ! Mage::app()->getRequest()->getParam('form_key', false)) {
            // flag request for ESI processing
            Mage::register('turpentine_esi_flag', true, true);
            return '{{form_key_esi_placeholder}}';
        } else {
            return parent::getFormKey();
        }
    }
public function getFormKey ( ) { if ( Mage :: registry ( 'replace_form_key' ) && ! Mage :: app ( ) -> getRequest ( ) -> getParam ( 'form_key' , false ) ) { // flag request for ESI processing Mage :: register ( 'turpentine_esi_flag' , true , true ) ; return '{{form_key_esi_placeholder}}' ; } else { return parent :: getFormKey ( ) ; } }
Retrieve Session Form Key

@return string A 16 bit unique key for forms
Retrieve Session Form Key