Secure data migration from fair contract signing and efficient data integrity auditing in cloud storage

With the rapid development of cloud storage, a growing number of data owners prefer to outsource their large-scale data to the remote cloud data centers, thus effectively avoiding the heavy burden of storing the massive data by themselves in local. Due to the promising market prospect, plenty of companies invest cloud storage and offer data storage services, which equipped with different access speed, using price, security, storage capacity, etc. For enjoying more suitable services, data owners might dynamically change cloud service providers and migrate the outsourced data blocks from a cloud data center to another one. However, the data integrity cannot be guaranteed during the migration process. In this paper, we study the challenge of secure outsourced data migration supporting fair contract signing and efficient data integrity auditing. Subsequently, we propose an efficient and practical solution to address this problem. Specifically, we adopt public blockchain to design a fair three-party contract signing protocol for outsourced data migration, which can effectively prevent data owners and cloud data centers from slandering each other maliciously. Meanwhile, we combine public blockchain and multicopy Merkle hash tree (M2HT) to design a secure data migration protocol with efficient data integrity auditing, which can guarantee the data integrity during the migration process. Next, we provide the formal security analysis, which demonstrates that our scheme can satisfy all of the expected security requirements without trusted third party. Finally, we also develop a prototype implementation and provide the performance evaluation, which can show the high-efficiency and practicality of our scheme.