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Security and Communication Networks
Volume 2017 (2017), Article ID 2508693, 11 pages
Research Article

Revocable Key-Aggregate Cryptosystem for Data Sharing in Cloud

Department of Computer Science, Jinan University, Guangzhou 510632, China

Correspondence should be addressed to Xiaoming Wang

Received 19 October 2016; Revised 7 February 2017; Accepted 20 February 2017; Published 12 March 2017

Academic Editor: Bruce M. Kapron

Copyright © 2017 Qingqing Gan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


With the rapid development of network and storage technology, cloud storage has become a new service mode, while data sharing and user revocation are important functions in the cloud storage. Therefore, according to the characteristics of cloud storage, a revocable key-aggregate encryption scheme is put forward based on subset-cover framework. The proposed scheme not only has the key-aggregate characteristics, which greatly simplifies the user’s key management, but also can revoke user access permissions, realizing the flexible and effective access control. When user revocation occurs, it allows cloud server to update the ciphertext so that revoked users can not have access to the new ciphertext, while nonrevoked users do not need to update their private keys. In addition, a verification mechanism is provided in the proposed scheme, which can verify the updated ciphertext and ensure that the user revocation is performed correctly. Compared with the existing schemes, this scheme can not only reduce the cost of key management and storage, but also realize user revocation and achieve user’s access control efficiently. Finally, the proposed scheme can be proved to be selective chosen-plaintext security in the standard model.