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

## TL;DR

This paper critically analyzes a revocable-storage identity-based encryption scheme for cloud data sharing, identifies correctness issues, and proposes modifications to ensure security and proper functionality.

## Contribution

It reveals correctness flaws in Wei et al.'s RS-IBE scheme and introduces a corrected, secure version of the scheme.

## Key findings

- Wei et al.'s RS-IBE scheme is incorrect in its original form.
- A modified scheme achieves correctness and security.
- The corrected scheme is suitable for secure cloud data sharing.

## Abstract

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.