ABSTRACT:In public cloud storage system protecting the data and controlling the dataaccess is a challenging issue. Cipher text Policy Attribute-Based Encryption(CP-ABE) has been adopted as a promising technique to provide flexible,fine-grained and secure data access control for cloud storage withhonest-but-curious cloud servers. However numerous works have been proposedusing CP-ABE scheme, in which the single attribute authority must execute thetime-consuming user legitimacy verification and secret key distribution andhence it results in a single-point performance bottleneck when a CP-ABE schemeis adopted in a large-scale cloud storage system. Clients may be stuck in thewaiting line for a long stretch to get their mystery keys, which results inlow-efficiency of the framework. Even though the multi authority access controlplans have been proposed, these plans still cannot conquer the disadvantages ofsingle-point bottleneck and low efficiency; because of the way that each of theauthority still autonomously deals with a disjoint characteristic set. In thiswork, it has been proposed a novel heterogeneous framework to remove theproblem of single point performance bottleneck and provide a more efficientaccess control scheme with an auditing mechanism. This framework employsmultiple attribute authorities to share the load of user legitimacyverification. Meanwhile, in this scheme, a CA (Central Authority) is introducedto generate secret keys for legitimacy verified users and each of theauthorities in our scheme manages the whole attribute set individually. Thissystem makes performance improvement in key generation and also guaranteessecurity requirement.
KEYWORDS: Cloudstorage, Access control, Auditing, CPABE.