More is Less: Perfectly Secure Oblivious Algorithms in the Multi-Server Setting
This work addresses the security and efficiency challenges in data privacy for cloud storage systems, showing a provable advantage in the multi-server setting.
The paper tackles the problem of whether multi-server Oblivious RAM (ORAM) can offer stronger security or better efficiency than single-server ORAM, and constructs a perfectly secure 3-server ORAM scheme that outperforms the best known single-server scheme by a logarithmic factor.
The problem of Oblivious RAM (ORAM) has traditionally been studied in a single-server setting, but more recently the multi-server setting has also been considered. Yet it is still unclear whether the multi-server setting has any inherent advantages, e.g., whether the multi-server setting can be used to achieve stronger security goals or provably better efficiency than is possible in the single-server case. In this work, we construct a perfectly secure 3-server ORAM scheme that outperforms the best known single-server scheme by a logarithmic factor. In the process, we also show, for the first time, that there exist specific algorithms for which multiple servers can overcome known lower bounds in the single-server setting.