Multicopy provable data possession scheme supporting data dynamics for cloud-based Electronic Medical Record system

In the era of big data, there are several insuperable research challenges in establishing Electronic Medical Record (EMR) for updating massive data with traditional methods. It is an attractive option to create the cloud-based EMR system, since cloud provides elastic and affordable data storage and management services. However, once the medical records are uploaded into the cloud, the owner will lose the control over the data, and sensitive contents might be accessed or modified by unauthorized entities. To address this issue, we propose a multicopy provable data possession for cloud-based EMR systems, which ensures the integrity and privacy of EMR data. In particular, to achieve data updates, we design a novel dynamic structure that improves the Merkle Hash Tree for multicopy storage, which achieves full dynamics efficiently and safely. Moreover, a random masking technique is employed in our proposal to generate distinguishable replica blocks of one block. Our construction prevents a verifier from obtaining medical records from challenge responses, but also eliminates exposing the content to unauthorized entities. Our security analysis shows that our scheme is provably secure. Evaluation experiments demonstrate that the proposal has lower communication and computation costs in comparison with the existing schemes.