Rewrite a snippet of code from PHP to NodeJS

I've been trying to rewrite a gateway bank plugin from PHP to NodeJS. This is the PHP code :

$processor = new RSAProcessor("certificate.xml",RSAKeyType::XMLFile);
$data   = "Some input gateway, like amount, merchantID ... ";
$data =  $processor->sign($data);

Exactly my problem is sign RSAKey to $data in NodeJS.

Any help would be much appreciated.

via Mohammad Goldast