Improved identity-based proxy-oriented outsourcing with public auditing for secure cloud storage

With the advent of cloud computing, it is an important problem to verify the integrity of data stored on cloud service providers by proxy while ensuring proxy's credibility. In 2019, Zhang proposed an identity-based proxy-oriented outsourcing with public auditing in cloud-based medical cyber-physical systems that outsourced medical data to cloud storage. Meanwhile the proxy is added for improving the speed of data processing. Unfortunately, some flaws are found in their approach in this paper. The signature generated by the agent can be forged to modify the original data. We have made some improvements based on the original protocol to improve the shortcomings of the original scheme. Finally, the security analysis shows that the security of the new protocol is enhanced.