Confidentiality is a major concern for cloud computing users who must ensure that their sensitive data is protected from unauthorized access or exposure, while still allowing for efficient sharing and collaboration among authorized parties. To address this challenge, a variety of encryption and access control techniques have been proposed and deployed, with varying levels of success.One promising approach to ensuring confidentiality in cloud computing is through the use of proxy re-encryption(PRE), which allows for the secure delegation of decryption rights from one party to another without...