A Hierarchical Key Management Scheme for Efficient Outsourced Computation in Cloud Storage Services

This study addresses the high computational overhead associated with updating encryption keys and authentication information by delegating these tasks to cloud storage services. This approach reduces the burden on data owners and facilitates the establishment of a robust cloud storage ecosystem. Our evaluation focuses on three critical performance metrics for cloud security mechanisms: 1. Computational Complexity: The processing time and frequency required for encryption, decryption, and verification. 2. Communication Complexity: The volume and length of message exchanges. 3. Storage Overhead: The space required to maintain a comprehensive cloud storage system. We propose a hierarchical key management scheme that enables data owners to update file encryption keys efficiently without impacting other users within the Cloud Storage Service (CSS) environment. By eliminating the need for owners to store all keys in a hierarchical tree, our scheme minimizes the computational cost of key updates. Ultimately, this approach enhances efficiency for both data owners and receivers, making it particularly suitable for resource-constrained mobile devices.