XMLSecurityDSig::processRefNode PHP Method

    public function processRefNode($refNode)
    {
        $dataObject = null;
        /*
         * Depending on the URI, we may not want to include comments in the result
         * See: http://www.w3.org/TR/xmldsig-core/#sec-ReferenceProcessingModel
         */
        $includeCommentNodes = true;
        if ($uri = $refNode->getAttribute("URI")) {
            $arUrl = parse_url($uri);
            if (empty($arUrl['path'])) {
                if ($identifier = $arUrl['fragment']) {
                    /* This reference identifies a node with the given id by using
                     * a URI on the form "#identifier". This should not include comments.
                     */
                    $includeCommentNodes = false;
                    $xPath = new DOMXPath($refNode->ownerDocument);
                    if ($this->idNS && is_array($this->idNS)) {
                        foreach ($this->idNS as $nspf => $ns) {
                            $xPath->registerNamespace($nspf, $ns);
                        }
                    }
                    $iDlist = '@Id="' . $identifier . '"';
                    if (is_array($this->idKeys)) {
                        foreach ($this->idKeys as $idKey) {
                            $iDlist .= " or @{$idKey}='{$identifier}'";
                        }
                    }
                    $query = '//*[' . $iDlist . ']';
                    $dataObject = $xPath->query($query)->item(0);
                } else {
                    $dataObject = $refNode->ownerDocument;
                }
            } else {
                $dataObject = file_get_contents($arUrl);
            }
        } else {
            /* This reference identifies the root node with an empty URI. This should
             * not include comments.
             */
            $includeCommentNodes = false;
            $dataObject = $refNode->ownerDocument;
        }
        $data = $this->processTransforms($refNode, $dataObject, $includeCommentNodes);
        if (!$this->validateDigest($refNode, $data)) {
            return false;
        }
        if ($dataObject instanceof DOMNode) {
            /* Add this node to the list of validated nodes. */
            if (!empty($identifier)) {
                $this->validatedNodes[$identifier] = $dataObject;
            } else {
                $this->validatedNodes[] = $dataObject;
            }
        }
        return true;
    }