EnclavePoSt: A Practical Proof of Storage-Time in Cloud via Intel SGX

Abstract

Data integrity is one of the most critical security concerns for users when using the cloud storage service. However, it is difficult for users to always stay online and frequently interact with storage service providers to ensure continuous data integrity in practice. The existing Proof of Storage-time schemes, enabling verifiable continuous data integrity checking at cost of performance, fail to provide flexible storage period, reliable measurement of storage time, and resistance to the outsourcing attack. In this paper, we propose EnclavePoSt, the first practical Proof of Storage-time via Intel SGX, where the data integrity checking can be automatically executed in a hardware-driven Trusted Execution Environment (TEE), i.e., the enclave, when users are offline. The checking results can be aggregated and efficiently verified by users. Besides, the elapsed time during isolated data integrity checking can be precisely measured, and the storage period is allowed to flexibly change. Lastly, our EnclavePoSt is resistant to the outsourcing attack. The security analysis and evaluations justify that the EnclavePoSt is more practical than previous works.