Know your target for accessing OPEN_ID Login Server / Rest URL.
Typically it’s like .
Check developer documentation for more details:
Test it with a "REST Client in browser" (for example, YARC! Extentions in Chrome) or open URL in Browser.
Output of this URL should be a JSON Document which contains all needed OpenID Specification information.
The picture below shows an example.
Download the certificate from OKTA-Server for HTTPS communication.
Select the Certificate on top.
Click View Certificate.
Click Copy to file.
Follow the Wizard to download the certificate as BASE-64 encoded X.509 (.CER) to your server.