Abstract
Recently, there is an exponential increase in the multimedia and other data over the Internet of Things (IoT). This data is generally send to the cloud for processing and storage. The fog layer in-between readily bridges communication among the IoT devices and the cloud. It delivers services efficiently by computing and analyzing various multimedia information generated by the IoT devices residing on the sensors. However, provision of effective security and energy are critical challenges. The purpose of this work is to enhance the secure transfer of information like multimedia. This scheme uses Message Queue Telemetry Transport (MQTT) protocol over SSL/TLS. Since MQTT is vulnerable to eavesdropping, the Elliptic curve-ElGamal cryptography algorithm is introduced which lends a homomorphic factor thereby mitigating man-in-the-middle attack. The dynamic key change and proportional offloading of data as proposed in the current research work helps to preserve node energy by selectively transferring data to the cloud and the fog according to the data topic. The results depict that the system security and lifetime can be improved in comparison to the existing protocols.