It actually is really easy to add the Virtru SDK to your project, as I’ll demonstrate through the construction of a “Protect & Share” Google Docs add-on.

I’m not familiar with Virtru but in this post from Trevor Foskett (Senior Solutions Engineer at Virtru) shows how their product can easily be integrated into Google Docs as an add-on. You’ll hopefully find this post useful to find out about Virtru as well as how client side and server side processing can be handled using Google Apps Script.

Source: Use Google Apps Script to Securely Share Google Docs