Achieving Secure and Fine-Grained Data Authentication in Cloud Computing Using Attribute Based Proxy Signature

Cloud computing has brought much convenience to human life, however, how to realize secure and fine-grained authentication of the data stored in the cloud is an urgent issue. In this paper, we center on the data authentication in cloud computing and propose a key insulated attribute based signature scheme (KI-ABPS) to provide secure and fine-grained data authentication in the cloud. Our scheme allows cloud server to generate a valid signature on behalf of the original signer. During the proxy process, the cloud server cannot obtain the private key of the signer, thus protecting the privacy of the signer. Furthermore, the lifespan of the system is divided into several discrete time slices. When time slice evolves, signer's private key will be updated. A proxy-sign key from past time slices is unable to generate a valid signature for the current time slice. This can guarantee both backward and forward security when key exposure or privilege revocation happens. By security analysis, our scheme has the essential unforgeability under chosen message attack.