I am working on an IoT project where we are using ATMega Micro Controllers as end devices. These devices need to communicate with REST services and post some sensitive data. The REST services are implemented using WebAPI 2 and transport layer is secured using TLS. We are using ESP8266 as the WiFi interface in the project. Making HTTP calls is not a problem.
How can we call to an HTTPS REST service using an IoT device such as Arduino or ATMega MCs? Where and how can we save the client certificates?