Tor Hidden Services: A Systematic Literature Review

Anonymous communications networks were created to protect the privacy of communications, preventing censorship and traffic analysis. The most famous anonymous communication network is Tor. This anonymous communication network provides some interesting features. Among them, we can mention that Tor can hide a user’s IP address when accessing to a service such as the Web, and it also supports Tor hidden services (THS) (now named onion services) as a mechanism to conceal the server’s IP address, used mainly to provide anonymity to websites. THS is an important research field in Tor. However, there is a lack of reviews that sum up the main findings and research challenges. In this article, we present a systematic literature review that aims to offer a comprehensive overview of the research made on THS by presenting the state-of-the-art and the different research challenges to be addressed. This review has been developed from a selection of 57 articles and presents main findings and advances regarding Tor hidden services, limitations found, and future issues to be investigated.

Tor Hidden Services: A Systematic Literature Review

Anonymous communications networks were born to protect the privacy of our communications, preventing censorship and traffic analysis. The most famous anonymous communication network is Tor. This anonymous communication network provides some interesting features, among them, we can mention user’s IP location or Tor Hidden Services (THS) as a mechanism to conceal the location of servers, mainly, web servers. THS is an important research field in Tor. However, there is a lack of reviews that sump up main findings and research challenges. In this article we present a systematic literature review that aims to offer a comprehensive view on the research made on Tor Hidden services presenting the state of the art and the different research challenges to be addressed. This review has been developed from a selection of 57 articles and present main findings and advances regarding Tor Hidden Services, limitations found, and future issues to be investigated.

A Privacy-Preserving Routing Protocol Using Mix Networks in Opportunistic Networks

This paper focuses on the problem of providing anonymous communications in opportunistic networks. To that end, we propose an approach using Mix networks that enables a relatively simple solution. Opportunistic networks present some constraints that make the deployment of typical network anonymity solutions difficult or infeasible. We show, utilizing simulations on the basis of real mobility traces, that the proposed solution is feasible for some scenarios by introducing a tolerable penalty in terms of message delay and delivery. To investigate the impact of routing strategies, we offer two different methods to select Mix nodes. From the experiment results, we show the trade-off between network performance and security.

ConsenSGX: Scaling Anonymous Communications Networks with Trusted Execution Environments

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.