With the rapid adoption of cloud computing, data security remains a critical concern, especially with the need for fine-grained access control mechanisms. Attribute-based encryption (ABE) has emerged as a promising solution, allowing the enforcement of access policies based on attributes associated with users. However, existing ABE schemes face challenges regarding revocation and management of multiple authorities, leading to inefficiencies in practical cloud environments. In this paper, we propose an efficient revocable multi-authority attribute-based encryption (MABE) scheme tailored for cloud systems, named Efficient Revocable Multi-Authority Attribute-Based Encryption for Cloud Storm (ERM-ABE).Our scheme enhances security and efficiency by allowing multiple authorities to manage different sets of attributes independently while maintaining a central encryption system. ERM-ABE addresses the issue of user revocation, ensuring that revoked users no longer have access to sensitive cloud data without requiring costly re-encryption or overhauling the entire system. We introduce a new revocation mechanism based on a combination of attribute updates and efficient ciphertext updates that minimize the computational overhead. Furthermore, the scheme incorporates hierarchical access control policies to enable fine-grained, scalable management of access rights in a multi-authority setting. The ERM-ABE scheme achieves optimal performance through reduced key and ciphertext sizes, significantly lowering the computational load compared to traditional approaches. The security of the scheme is proven under standard cryptographic assumptions, ensuring robustness against potential attacks. Finally, we demonstrate the practical  applicability of ERM-ABE by evaluating its performance in real-world cloud scenarios, showing a significant improvement in both efficiency and scalability. Our work provides a robust foundation for secure and manageable cloud-based encryption, advancing the state of access control in multi-authority cloud environments.

KEYWORDS: Attribute-Based Encryption (ABE), Multi-Authority, Revocation, Cloud Security, Access Control, Fine-Grained Access, Cloud Computing, Scalability, Ciphertext Size Reduction, Data Privacy, Efficient Encryption