This work presents FDTLS, a security framework that combines storage and network/communication-level security for resource limited Internet of Things (IoT) devices using Datagram Transport Layer Security (DTLS). While coalescing storage and networking security scheme can reduce redundent and unnecessary operations, we identify security- and system-level challenges that can occur when applying DTLS. FDTLS addresses these challenges by employing asymmetric key generation, a virtual peer, and header reduction-based storage optimization. Our results obtained using a Contiki-based implementation on OpenMote platforms show that compared to using storage and networking security separately, FDTLS can reduce the latency of packet transmission responses and also contribute to saving energy. © 2019 Copyright held by the owner/author(s).