On the Analysis of the Revocable-Storage Identity-Based Encryption Scheme

Cloud computing can provide a flexible way to effectively share data among multiple users since it can overcome the time and location constraints of computing resource usage. However, the users of cloud computing are still reluctant to share sensitive data to a cloud server since the cloud server should be treated as an untrusted entity. In order to support secure and efficient data sharing in cloud computing environment, Wei et al. recently extended the concept of identity-based encryption (IBE) to support key revocation and ciphertext update functionalities, and proposed a revocable-storage identity-based encryption (RS-IBE) scheme. In this paper, we show that the RS-IBE scheme of Wei et al. does not satisfy the correctness property of RS-IBE. In addition, we propose a method to modify the existing RS-IBE scheme to be a correct and secure scheme.