The key to realizing the smart functionalities envisioned through the Internet of Things (IoT) is to securely and efficiently communicate, store, and make sense of the tremendous data generated by IoT devices. Therefore, integrating IoT with the cloud platform for its computing and big data analysis capabilities becomes increasingly important, since IoT devices are computational units with strict performance and energy constraints. However, when data is transferred among interconnected devices or to the cloud, new security and privacy issues arise.