Right now, our users are creating "self signed certificates" in order to digitally sign documents using Adobe Acrobat Standard DC. This is not ideal, however, since employees can easily impersonate one another.
Is there a way for us to create, administer, and distribute our own certificates to employees ourselves to increase identity assurance or is using a third party's certificates (ie Entrust) the only way?
Ie is there an in-house solution for us to create our own certificates rather than employees using self-signed certificates?
First of all, how are those signatures used? Just internally in your organization? Or are arbitrary people receiving them? Or something in-between? If only internally, setting up an own PKI is feasible. If arbitrary people are involved and want to verify your signatures, you need to use a commonly trusted PKI. Anything in-between needs to be analyzed.
If you get to the conclusion that an own in-house PKI would suffice, there are numerous PKI products out there you can use, some for free, some not for free.
Considering your question, though, there doesn't seem to be any sufficient expertise in your company (or you don't trust it) in regard to PKIs. So you should ask a security expert to help you build your PKI because for a secure PKI (that prevents misuse) you need more than some software, you have to build secure processes around it to ensure trust.