This article explains more and essentially, Google doesn't provide the encrypted keyword and we wouldn't be able to get it to show.
What does "Unknown keywords (SSL)" mean?
In September 2013, Google made a change that encrypts the search results for its users. As a result, web analytics packages, such as HubSpot, cannot identify the keywords that generate organic search traffic from websites.
Visits originating from most Google searches are now bucketed under Unknown keywords (SSL) within the Sources tab.
For the Paid Search (PPC) category, if the visit originates from Google's HTTPS address (e.g., from users logged into their Chrome browser or other Google apps), you will see Unknown keywords (SSL) listed in the PPC category.