ConsenSGX: Scaling Anonymous Communications Networks with Trusted Execution Environments

Abstract

Anonymous communications networks enable individuals to maintain their privacy online. The most popular such network is Tor, with about two million daily users; however, Tor is reaching limits of its scalability. One of the main scalability bottlenecks of Tor and similar network designs originates from the requirement of distributing a global view of the servers in the network to all network clients. This requirement is in place to avoid epistemic attacks, in which adversaries who know which parts of the network certain clients do and do not know about can rule in or out those clients from being responsible for particular network traffic. In this work, we introduce a novel solution to this scalability problem by leveraging oblivious RAM constructions and trusted execution environments in order to enable clients to fetch only the parts of the network view they require, without the directory servers learning which parts are being fetched. We compare the performance of our design with the current Tor mechanism and other related works to show one to two orders of magnitude better performance from an end-to-end perspective. We analyse the requirements to actually deploy such a scheme today and conclude that it would only require a small fraction (<2.5%) of the relays to have the required hardware support; moreover, these relays can perform their roles with minimal network bandwidth requirements.

WhisperChord: Scalable and Secure Node Discovery for Overlay Networks

“…While PIR-Tor considerably reduces the network load due to the decreased amount of node discovery data transmitted, it creates an additional computational overhead on the DAs and DCs caused by the operation mode of the applied PIR methods. Sasy and Goldberg [16] apply Oblivious RAMs with trusted execution environments to improve the scalability of Tor. Komlo et al [7] have recently proposed a set of protocols and algorithms that reduce the amount of node information Tor users should maintain for creating paths.…”

Weaving a Faster Tor: A Multi-Threaded Relay Architecture for Improved Throughput

“…Much like PIR-Tor, ConsenSGX [SG19] allows clients to request relay information from directory servers in a privacy-preserving manner. Rather than using PIR, ConsenSGX combines oblivious RAM (ORAM) [GO96] and trusted execution environments to provide more-efficient directory servers.…”

Metadata-Private Resource Allocation in Edge Computing Withstands Semi-Malicious Edge Nodes

“…Unprotected metadata will expose the end device's private information; e.g., a malicious adversary can launch a side-channel attack by observing how the gateway performs the resource allocation to obtain the user's privacy information [10]. Some research has shown that it is possible to get a detailed and private picture of a person's contacts and interests just by analyzing metadata, and it is technically much more accessible to search massive amounts of metadata than to listen in on millions of phone calls [11]. In recent years, some researchers have focused on the metadata privacy in secure messaging [12,13], however, in the area of edge computing, we still face the challenge of lower computation resources on the end devices and lower bandwidth requirements.…”