Cloud cloud server may also fraud the eligible

Cloud computing uses advanced computational power and improved storage capabilities. Cloud computing is a long dreamed vision of computing utility, which enable the sharing of services over the internet. Presently cloud computing technology is mostly used to
store the large amount of data. Within this computing environments, the cloud servers can offer various data services, such as remote data storage and outsourced delegation computation for data storage, the servers also store a large amount of data, which could be accessed by authorized users. For delegation computation, the servers could be used to handle and calculate numerous data according to the users demands. To reduce the cost, the users which have a limited computing power are nevertheless more likely to delegate the mask of the decryption task to the cloud servers.\
The result shows, attribute-based encryption with delegation come out. Still, there are some problems and questions regarding to
previous related works. For example, during the delegation or release, the cloud servers could misrepresent or replace the delegated ciphertext and respond a fake result. As well as for the purpose of cost saving the cloud server may also fraud the eligible users by responding them that they are unworthy. Even, the access policies may not be flexible during the encryption. Since policy for general circuits are used to achieve the strongest form of access control, a construction to design circuit ciphertext-policy attribute-based encryption with timespecified attributes scheme has been developed.In this scheme, every ciphertext is labeled with some attribute and a time interval while private key is associated with a time instant. The ciphertext can only be decrypted if the attributes associated with the ciphertext satisfy the keys access structure.This system is mixed with verifiable computation the data confidentiality, the fine-grained access control as well as the correctness of the delegated computing results are well guaranteed at the same time. Moreover, this scheme achieves feasibility as well as efficiency.