Symptoms
We are concerned about getting our SSL environment working over the course of a weekend. One of the things that we are currently concerned about is whether or not we'll be able to get K2 working with SSL in a timely manner. If K2 for SharePoint works insecure in an SSL SharePoint 2013 site, it would allow us to tackle that issue on another date. Please let us know if this configuration would work, at least temporarily
Diagnoses
The support matrix is included an attachment. SharePoint HTTPS supports K2 HTTPS
Resolution
The document answers the question:
http://help.k2.com/onlinehelp/k2forsharepoint/ICG/current/default.htm_Install_Topics/Before/SecurityAuth.htm