Seamless communication with WSN devices has facilitated the development of various Internet of Thing (IoT) applications. The information communication technologies being developed for this purpose are currently centered around an adaptation layer, specifically IPv6 over Low Power Wireless Personal Area Networks (6LoWPAN), and are constrained by the Constrained Application Protocol (CoAP). A significant challenge in CoAP communications with internetintegrated wireless sensor networks is ensuring end-to-end security, particularly due to the high computational costs associated with elliptic curve cryptography (ECC) on resource-limited wireless sensing devices. Additional concerns include the incompatibility of end-to-end security with CoAP proxies and the limitations of wireless sensor nodes. The mechanism proposed in this research tackles these challenges effectively. It utilizes a DTLS-based security protocol that facilitates a transparent DTLS handshake with mutual authentication, aimed at reducing the computational load on constrained sensor nodes while offloading intensive ECC computations to more powerful devices. The implementation employs pre-shared key authentication for sensor nodes, along with a security protocol that guarantees both mutual authentication and confidentiality within the wireless sensor network (WSN) environment during end-to-end communications. The outcomes of this research have positively impacted both power consumption and memory usage in WSN devices. The proposed approach can be seamlessly integrated into applications running on internet clients (CoAP clients), and sensors node (CoAP servers). Overall, this system enhances end-to-end security for IoT applications while conserving resources in WSN nodes. Keywords: DTLS, CoAP, ECC, IoT, 6LoWPAN, and WSN.