Cloud storage enables users to remotely store their data and enjoy the on-demand high-quality cloud applications without the burden of local hardware and software management. Though the benefits are clear, such a service is also relinquishing users’ physical possession of their outsourced data, which inevitably poses new security risks towards the correctness of the data in the cloud. In order to address this new problem and further achieve a secure and dependable cloud storage service, we propose in this paper We develop a new cryptosystem for fine-grained sharing of encrypted data that we call Key-Policy Attribute- Based Encryption (KP-ABE). In our cryptosystem, ciphertexts are labeled with sets of attributes and private keys are associated with access structures that control which ciphertexts a user is able to decrypt. Attribute- based encryption (ABE) has been envisioned as a promising cryptographic primitive for realizing secure and flexible access control. HASBE extends the ASBE algorithm with a hierarchical structure to improve scalability and flexibility while at the same time inherits the feature of fine-grained access control of ASBE.