<p>The rapid expansion of the Internet of Things (IoT) has created new challenges for secure, efficient, and scalable authentication, particularly in decentralized environments where traditional centralized solutions may face limitations. In response to these challenges, we propose a novel decentralized authentication scheme that integrates Elliptic Curve Cryptography(ECC) with a dynamic difficulty adjustment mechanism based on an adaptive logistic growth model. This scheme aims to provide robust security while maintaining low computational and communication overhead, making it suitable for resource-constrained IoT devices. The proposed scheme is evaluated through a combination of theoretical and practical analyses. A BAN logic proof is provided to establish the correctness of the authentication protocol, and a mathematical security analysis demonstrates resistance to common attacks, such as replay and man-in-the-middle attacks. The scheme is implemented on the Ethereum blockchain using Remix IDE, with an analysis of gas costs for various operations, such as contract deployment and role management, to validate its feasibility in a real-world blockchain environment. Additionally, computation and communication time analyses are conducted to assess the scheme’s efficiency compared to existing solutions. To further validate performance, the scheme is simulated using NS3, demonstrating its scalability and effectiveness in large-scale IoT networks. The results suggest that the proposed authentication scheme enhances security while optimizing performance, offering a promising solution for modern IoT applications. </p>