Swiss researchers describe HORNET, an analogue of Tor that works faster

The anonymous cryptographic network of Tor virtual tunnels has a number of advantages. Tor easily changes the connection address, allowing you to enter the normal Internet using the IP of one of the output nodes. You can also host hidden websites on the Tor network that cannot be set to a physical location (at least in theory ). This makes Tor a tool for political activists, drug dealers, journalists, and regular Web users. For all its appeal and security from wiretapping and tracking, Tor has a significant drawback: it runs too slowly. Researchers from the Swiss Higher Technical School of Zurich have created a concept of a toroid-like anonymous network that works faster.

The team named their creation High-speed Onion Routing at the NETwork layer or HORNET. In a paper published last week , they described the principles of the proposed concept, which in theory could be the next generation of Tor. Already in the summary, they promise the speed of traffic transmission through separate nodes up to 93 Gbit / s. Researchers say the ability to quickly add new users to the network.

Like Tor, HORNET uses a multilayer onion network structure. Each of the nodes decrypts the “onion” layer to obtain data on where to transfer the portion of the data. Then the packet is passed to the next node. HORNET uses two versions of the onion protocol to protect anonymity: one for access to the public Internet, and the second uses a modified version of the Tor meeting point protocol to access hidden web sites.

To access the insecure site in the external network uses HORNET torus-protocol onion marshutizatsii Sphinx. The source creates for each node a pair of symmetric keys using the Diffie-Hellman protocol. The keys are used to encrypt the so-called Forwarding Segment (forwarding segment), a fragment that contains information about the transmission status, hopes, information about subsequent data packets, and so on.

To transfer the actual data, forwarding segments are collected from each of the nodes in the chain to what the researchers called anonymous header (AHDR, anonymous header). Each node gains access to its own forwarding segment without disclosing path information, except for data on the past and next nodes. The data is encrypted using keys for each of the nodes; during transmission, cryptographic layers are removed. According to the researchers, the advantage of this scheme is an interesting reduction in the computational load for transmitting each packet and the amount of transmitted service data about the connection. HORNET Package Type Comparison



But Tor also has .onion sites that can only be accessed within an anonymous network. To hide both the client and the site server, a system of meeting points is used, which eliminates the possibility of wiretapping traffic. The hidden site selects the meeting point, then information about the connectivity signed by the cryptographic key is published in the distributed database - the handle of the hidden service. Later, when building the request, the client finds data about the meeting point and from there starts the connection. In HORNET, common methods are similar with slight differences in detail and terminology. For example, a hidden service descriptor here is called AHDR. There are a number of useful improvements. As the meeting points become obsolete, the client and the hidden service can choose a new meeting point, which will give a faster connection. A hidden service, when announcing its own existence, can select several meeting points, and the client will be able to choose one with the best channel for him. The downside to Tor is the doubled header size.

Researchers also tested the ability to embed HORNET hosts in software routers. HORNET code was inserted into Intel software routers using the Data Plane Development Kit (DPDK) version 1.7. The HORNET client was written in Python. According to the researchers, no other anonymous network was written at the router SDK level.

A separate chapter of the report is devoted to safety research. Like Tor, HORNET is vulnerable. If government agencies or any other attackers control more than one node on the data path, they can try to carry out an attack to identify traffic. This will require analysis of timing and traffic paths, packet labels, and other methods that some studies have shown work against Tor. HORNET is not able to protect against such attacks aimed at individual users, the researchers admit.

Based on materials from Ars Technica . arXiv: 1507.05724 [cs.CR]. Photograph of Abispa ephippium , James Nyland, CC BY 2.0.