Our organisation wants to purchase a digital signature certificate for signing financial PDF documents. We want to automate this process, so we'll be having Java code do the signing work. For that the only way, supposedly, is to keep the certificate as a file on the server.
I've contacted many digital certificate vendors and with none it was possible to get a basic certificate file. All were issuing a hardware token such as pen drive, USB dongle etc. which contain certificate file in non-extractable format. None give the option to download.
Why is that? Is there some regulation that digital signature certificate can only be given in form of hardware token for security reasons? If not, then which vendors allow to download certificates on system?
Any suggestion or reference is appreciated.