Paper 2026/481

Remise: Authorized Anonymous Communication Systems

Abstract

We present Remise, a two-server authorized anonymous communication system built on Distributed Oblivious RAM (DORAM). Remise supports two modes of opera- tion: (i) an anonymous bulletin board, where messages are publicly revealed at the end of each epoch without linking senders to messages, and (ii) anonymous commu- nication channels, where messages remain secret-shared, and writers selectively grant and revoke read access to chosen readers. In both modes, the two servers execute read and write operations without learning which indices are accessed, which authorization tokens are used, or which relationships exist between writers and readers, assuming at least one honest server. A central contri- bution of Remise is a lightweight and efficient access- control mechanism. Authorization proofs are maintained in secret-shared form across the two servers, enabling oblivious verification while preventing leakage even un- der client–server collusion. Unlike prior DPF-based sys- tems, Remise provides built-in auditing by having the semi-honest servers generate standard-basis vector shares internally, eliminating the need for server-side DPF va- lidity checks. We implement a prototype of Remise and evaluate it under realistic network conditions. Our ex- periments show 80×improvement in online server time when compared to PACL (Spectrum) (IEEE S&P 2023) for databases of size $22^{24}$