From mozilla.dev.security.policy : – the relevant extension coding techniques in Mozilla are: * Use the observer-service to register a « http-on-examine-response » observer. * When you observe this event, use channel.QueryInterface(Ci.nsIHTTPChannel) to get the HTTP channel from it * Pull the securityInfo attribute of that channel * Use QueryInterface(nsISSLStatusProvider) on the securityInfo to access the SSL data […]