PRISEC III, a cryptographic framework created to improve security and efficiency in IoT environments with scarce assets, is presented in this article. It has a four-tier encryption model (Guest, Basic, Advanced, and Admin) that uses progressively more complex encryption techniques to balance security and performance. PRISEC III maximizes efficiency while guaranteeing secure key exchange by combining symmetric (AES, ChaCha20, Blowfish) and asymmetric (ECC, RSA) encryption. Higher tiers employ multi-layer encryption for crucial operations, while lower tiers use lightweight encryption to minimize computational overhead. Scalability and resource optimization are further improved by hybrid encryption and edge computing. Performance tests verify that PRISEC Ill can handle IoT constraints while offering scalable, secure data transfer. This study provides an organized method for choosing cryptographic protocols, which helps create effective and flexible security solutions for Internet of Things applications.

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Hybrid encryption techniques,Multi-level encryption,Symmetric and asymmetric encryption,Computational efficiency,Cryptographic algorithms

• Ciências da Computação e da Informação - Ciências Naturais
• Engenharia Eletrotécnica, Eletrónica e Informática - Engenharia e Tecnologia