- Ensure you have an SSL certificate for the K2 site. Your options are either an SSL certificate from public CA (costs money and desirable/required when K2 site is accessed from internet/outside of your corporate network) or an internal CA. In a worst case scenario / for testing you can use a self-signed certificate (which can be easily generated using PowerShell, but you need to ensure that it will be trusted on the client side - this can be done using AD DS group policies or manually on each machine). This is something to be handled by your IT infrastructure team, and not a K2 specific thing, hence it is not documented in K2 product documentation.
- Next you need to add HTTPS bindings for the K2 site (and preferably remove the HTTP one, if there is no explicit need/requirement to keep it) and then reconfigure K2 using Setup Manager ensuring you've selected the new HTTPS binding and made it the default.
- When you change your SharePoint to HTTPS, changing K2 to HTTPS is not an optional nice to have thing - it is a requirement. K2 requires schema match for K2/SharePoint - they both must be on HTTP or on HTTPS.
See more details here: K2 Five Installation and Configuration Guide - Security and Authentication (On-Prem and Online), look under SSL Requirements for K2 Site.
- K2 does not provide documentation on how you should change SharePoint to use HTTPS (you should look for documentation from Microsoft).
- After changing K2 to use HTTPS you will need to re-run the K2 App Registration Wizard as your K2 URL has changed from HTTP to HTTPS.