The paper introduces a lightweight, secure authentication and key management scheme for IoT devices to address critical security issues in weak environments. The proposed design principles are said to be crafted based on a comprehensive study of security threats and requirements for the IoT device, with efficiency, security, ease of use, and scalability as the goals. An encouraging authentication protocol design in the lightweight Elliptic Curve Cryptography (ECC)-based approach and key management scheme is applied. From the experimental and simulation results, it was indicated that the scheme is still reasonably secure and operates under fundamental length changes and data packet size. It ensures that authentication time and computation overhead stay within an acceptable range. Therefore, this dynamic key updating mechanism defeats possible threats of key leakage and theft, thereby enhancing system security. As a result, there is an effective and dependable solution for secure authentication with IoT hardware key management. The solution can be widely applied in practice and promotion.