Read or count pages of a digital signed pdf document using php or javascript

I am trying to read a pdf which is digitally signed. I tried using different php libraries and also js libraries, each of them works well with a normal pdf document but if the document is digitally signed then it cant read it. Tried libraries mpdf, setassign/fpdi etc. I even tried to remove the digital signature and make a copy of it and then count the pages of the document using ghostscript but not working, but it can’t remove the sign, Is there any way around to do it ? any idea would be appreciated.