With the rapid development of cloud storage, an increasing number of data owners prefer to store their large-scale data on the remote cloud for greatly reducing the burden of maintaining the data by themselves. Since different cloud storage service providers offer distinct quality of data storage services, secure outsourced data migration becomes a fundamental requirement for data owners to change their cloud storage service providers. As a result, how to guarantee the correctness and integrity of the outsourced data blocks when they are being migrated from one semi-trusted cloud host to another becomes a primary concern of data owners. To solve this problem, we propose a blockchain-based publicly verifiable data migration scheme supporting efficient data integrity checking for cloud storage in this paper. Specifically, the data owner can dynamically change the cloud storage service providers and securely migrate the outsourced data from one cloud host to another, without retrieving the transferred data from the original cloud host, and checking the transferred data integrity in the target cloud host. By making use of blockchain, our proposed scheme can simultaneously achieve data migration and integrity checking without interacting with a third party auditor, thus avoiding the problems of service interruption and privacy leakage caused by the single-point-of-failure of the third party auditor, which is much better than the previous schemes. Meanwhile, our proposed scheme is provable secure in the random oracle model. Finally, we also develop a prototype implementation of our proposed scheme and compare the efficiency with some existing schemes. The experimental result demonstrates that our proposed scheme is more efficient and practical.

随着云存储的快速发展，越来越多的数据拥有者更愿意将自己的海量数据存储在异地云端，大大减轻了自己维护数据的负担。由于不同的云存储服务提供商提供不同质量的数据存储服务，安全的外包数据迁移成为数据所有者更换云存储服务提供商的基本要求。因此，如何保证外包数据块在从一台半可信云主机迁移到另一台云主机时的正确性和完整性，成为数据所有者关心的首要问题。为了解决这个问题，我们在本文中提出了一种基于区块链的可公开验证的数据迁移方案，支持对云存储进行高效的数据完整性检查。具体来说，数据拥有者可以动态更换云存储服务商，安全地将外包数据从一台云主机迁移到另一台云主机，无需从原始云主机取回传输数据，也无需检查目标云主机中传输数据的完整性。通过利用区块链，我们提出的方案可以在不与第三方审计师交互的情况下同时实现数据迁移和完整性检查，从而避免了第三方审计师单点故障导致的服务中断和隐私泄露问题，这比以前的方案要好得多。同时，我们提出的方案在随机预言机模型中是可证明安全的。最后，我们还开发了我们提出的方案的原型实现，并将效率与一些现有方案进行了比较。