The Internet of Things (IoT) is a transformative technology that has found applications in diverse domains, including automation, logistics, grid, transportation, healthcare, and more. In these domains, IoT systems generate a significant amount of data, which can be stored in a cloud. However, cloud computing may not be practical in certain delay‐sensitive IoT applications with complex operations. To address this, fog and edge computing paradigms have been introduced, but they rely on a reliable internet connection for proper functioning. The dew computing paradigm, a novel concept, allows the execution of various applications in the IoT environment, with or without internet connectivity. However, ensuring data confidentiality and integrity during transmission and storage in such an environment remains a significant challenge. Therefore, a fail‐safe and highly effective security mechanism is yet to be proposed. This study introduces a protocol that utilizes the elliptic curve cryptography and secure hash algorithm to design a secure key agreement and lightweight protocol (SKALP). SKALP security is formally analyzed using BAN (Burrows‐Abadi‐Needham) logic, ROM (Random Oracle Model), RoR (Real‐Or‐Random) model, and ProVerif (Protocol Verifier) simulation while informally discussing it to evaluate its resistance against well‐known attacks. Additionally, the performance analysis of SKALP considers the costs associated with communication and computation. The findings from the comparative analysis indicate that the SKALP demonstrates a higher level of superiority than its competitors.