Efficient and Secure Cloud Data Sharing Using CP-ABE Supporting Dynamic Attributes

Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is a cryptographic primitive that provides confidentiality and fine-grained access control for data sharing in untrusted cloud environments. It allows data owners to set access policies based on attributes, ensuring only users who meet the criteria can decrypt and access the data. However, existing CP-ABE systems are inherently designed for static attributes and lack efficient support for dynamic user attributes, often necessitating frequent key updates and complex revocation processes. To address these challenges, we propose an enhanced CP-ABE cryptosystem that allows for the dynamic generation of additional key components, which can be efficiently integrated with the user's existing key. The user private key is assigned attribute-level expiration tags, facilitating instant revocation. Additionally, our scheme facilitates the secure offloading of partial decryption of ciphertext to the cloud server using a transformed private key, thus reducing the computational overhead on resource-constrained user devices. Our proposed cryptosystem provides a secure and scalable approach for managing dynamic attributes in cloud environments with rapidly evolving access requirements.