Large-scale certificate management on multi-tenant web servers

Abstract

For large-scale certificate management of multi-tenant web servers, preloading numerous certificates for managing numerous hosts under the single server process results in increasing the required memory usage because of the respective page table entry manipulation, which might be a poor resource efficiency and a reduced capacity. To resolve this issue, we propose a method for dynamic loading of certificates bound to the hostnames found during the SSL/TLS handshake sequences without preloading, provided that the Server Name Indication (SNI) extension is available. We implemented the function of choosing the respective certificates with the ngx mruby module, which extends web server functions using mruby with a small memory footprint while maintaining the execution speed. The proposed method was evaluated by a web hosting service employing the authors.