Abstract: Cloud computing is most Prominent Solution for large data storage and data sharing, which has lot of benefits for industry and individuals. However, there exists a natural problem for directly outsource and share the data in the cloud server since the they contain valuable information so it requires the high-level security. It is necessary to provide the highly cryptographically access control Mechanism for data sharing. Therefore, in this project we use Identity-based encryption, which is a promising cryptography technique for building a practical data sharing system. Since access, control is not a static mechanism. When some userís authorization is expired, there should be a mechanism that can remove him/her from the system. In addition, we need to check the revoked user cannot access both the previously and subsequently shared data. So has to make this system to be implement we propose revocable-storage identity-based encryption, which can provide the forward/backward security of cipher text by introducing the functionalities of user revocation and cipher text update simultaneously. The proposed RS-IBE scheme has advantages in terms of functionality and efficiency, and thus is feasible for a practical and cost-effective data-sharing system. Finally, we provide implementation results of the proposed scheme to demonstrate its practicability.

Keywords: Revocation, Encryption, Key Exchange, Private key generator, cipher text.