EHAP-ORAM: Efficient Hardware-Assisted Persistent ORAM System for Non-volatile Memory

Oblivious RAM (ORAM) protected access pattern is essential for secure NVM. In the ORAM system, data and PosMap metadata are maps in pairs to perform secure access. Therefore, we focus on the problem of crash consistency in the ORAM system. Unfortunately, using traditional software-based support for ORAM system crash consistency is not only expensive, it can also lead to information leaks. At present, there is no relevant research on the specific crash consistency mechanism supporting the ORAM system. To support crash consistency without damaging ORAM system security and compromising the performance, we propose EHAP-ORAM. Firstly, we analyze the access steps of basic ORAM to obtain the basic requirements to support the ORAM system crash consistency. Secondly, improve the ORAM controller. Thirdly, for the improved hardware system, we propose several persistence protocols supporting the ORAM system crash consistency. Finally, we compared our persistent ORAM with the system without crash consistency support, non-recursive and recursive EHAP-ORAM only incurs 3.36% and 3.65% performance overhead. The results show that EHAP-ORAM not only supports effective crash consistency with minimal performance and hardware overhead but also is friendly to NVM lifetime