More is Less: Perfectly Secure Oblivious Algorithms in the Multi-Server Setting presented at Asiacrypt2018 2018

by Jonathan Katz, Elaine Shi, T-h. hubert Chan, Antigoni Polychroniadou, Kartik Nayak,

Summary : The problem of Oblivious RAM (ORAM) has traditionally been studied in the 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.