HORNET: High-speed Onion Routing at the Network Layer (1507.05724v3)

Abstract: We present HORNET, a system that enables high-speed end-to-end anonymous channels by leveraging next generation network architectures. HORNET is designed as a low-latency onion routing system that operates at the network layer thus enabling a wide range of applications. Our system uses only symmetric cryptography for data forwarding yet requires no per-flow state on intermediate nodes. This design enables HORNET nodes to process anonymous traffic at over 93 Gb/s. HORNET can also scale as required, adding minimal processing overhead per additional anonymous channel. We discuss design and implementation details, as well as a performance and security evaluation.

• The paper presents HORNET, a novel system that eliminates per-flow state by integrating onion routing at the network layer.
• It achieves over 93 Gb/s throughput on commodity hardware while robustly defending against passive and active de-anonymization attacks.
• The design embeds session state within packet headers using a Sphinx-based setup to ensure efficient and scalable anonymous data forwarding.

Analysis of HORNET: High-speed Onion Routing at the Network Layer

The paper under discussion presents HORNET, an anonymity system that pioneers the integration of onion routing at the network layer, leveraging next-generation Internet architecture. As a low-latency mechanism, HORNET is distinguished by its adoption of symmetric cryptography for data forwarding, eliminating the need for per-flow state on intermediate routers. This design choice permits a staggering processing capability of over 93 Gb/s on generic hardware.

HORNET stands out due to its scalability and minimal processing overhead per anonymous channel, contrary to traditional systems like Tor that suffer from performance bottlenecks due to their overlay architecture and requirement for maintaining per-connection state. The choice of network-layer integration offers the additional benefit of allowing the use of symmetric keys to protect payloads, thereby securing the data from multiple network vantage points, which is significant for defending against pervasive surveillance programs.

The core of HORNET's architecture includes a setup phase employing Sphinx for session establishment and an innovative header construction that eliminates state storage by embedding per-session state information into packet headers. This approach ensures efficient operation across intermediate nodes by facilitating symmetric operations only on data packets, enhancing throughput significantly compared to existing methods.

The paper outlines several contributions:

1. Implementation and evaluation of HORNET, which integrates source-selected paths and shared keys to support onion routing without maintaining state at network relays.
2. Security analysis demonstrating robust resistance to passive attacks and specific active attacks, showcasing superior security assurances in comparison to existing network-level systems.
3. Performance evaluation revealing anonymous data processing rates up to 93.5 Gb/s, a throughput on par with high-end commodity routers, thereby validating the system's practical deployment potential.

HORNET's problem definition aims at ensuring relationship anonymity under mass surveillance scenarios, with distinct guarantees for sender and sender-receiver anonymity. The adversarial model considers nodes that could compromise parts or the entirety of paths between communicating hosts, but not end hosts concurrently. Further, it specifies desired anonymity properties, including integrity and path secrecy, whereby routing information remains confidential and packet correlation is mitigated effectively.

The structure of HORNET, detailed through path and certificate retrieval, threat models, and its underlying cryptographic modules, emphasizes the importance of distributing path state across packets. By doing so, the proposed design achieves a reduction in the processing burdens associated with state management in traditional network designs.

Security analysis in the paper inspects areas such as passive and active de-anonymization, payload protection, and resilience against denial-of-service (DoS) attacks. The approach ensures that path details remain obscure, which is critical to deflecting topology-based analysis and reduces potential de-anonymization avenues.

HORNET is evaluated in a controlled testbed setting juxtaposed against other schemes, demonstrating efficiencies in data forwarding latency and goodput across various packet payload sizes. The scalability assessment conducted illustrates its capacity to handle vast data flows without degradation in speed, critical for future Internet scale deployment.

In terms of future directions, the paper references the potential integration of HORNET with vehicular architectures and its adaptability with security mechanisms across diverse network layers. The discussed limitations, notably the challenges around targeted confirmation attacks and the trade-off concerning perfect forward secrecy, are constructive critique points guiding future enhancements.

HORNET's innovation contributes both theoretically and practically, redefining possibilities for high-speed, scalable, and secure anonymous communication. Discussions on the potential impact of path knowledge on anonymity sets, together with the examination of network performance, provide a comprehensive foundation for HORNET's applicability in real-world scenarios. This research suggests that integrating anonymity features into network infrastructure poses not only a feasible but a necessary evolution to enhance privacy protection measures in increasingly surveilled environments.