Certificateless Public Verification for Data Storage and Sharing in the Cloud

By advances in cloud computing, users are allowed to remotely store their data in the cloud, manage the stored data without limitation of time and place, and give rights to visitors that want to access to their data. As may no longer possess data physically, the data owner has to ensure the integrity of the data with the public key given by Public key infrastructure (PKI). However, there are many security risks of the traditional PKI and the certificate management is complex. We utilize elliptic curve group to propose a certificateless signature to solve the above problem. To check the integrity of files stored in the cloud, we design a certificateless public verification mechanism based on the signature and further extend it to support batch auditing tasks. Meanwhile, an efficient key updating method is proposed to provide visitors a friendly data success environment. The security analysis proves that the proposed scheme is secure under the discrete logarithm assumption. Extensive theoretical analyses and experimental results show the effectiveness of the proposed scheme.