Remote Server Certificates
From SOPWiki
About Certificates
The remote admin application uses SSL to encrypt all transmission between client and server. To do this, the server needs to have a private key and certificate installed. A default key and certificate are provided, but you may wish to make your own for added security.
Generating a Certificate
Follow the instructions on this external page for instructions on how to make a self-signed SSL certificate: How to create a self-signed SSL Certificate
Installing Your Certificate
After following the instructions in the link above, copy the server.crt file to {gamedir}\addons\SourceOP\remote.crt and the server.key file to {gamedir}\addons\SourceOP\remote.key. These are the certificate and private key files respectively.