Modern low-latency anonymity systems, no matter whether constructed as an overlay or implemented at the network layer, offer limited security guarantees against traffic analysis. On the other hand, high-latency anonymity systems offer strong security guarantees at the cost of computational overhead and long delays, which are excessive for interactive applications. We propose TARANET, an anonymity system that implements protection against traffic analysis at the network layer, and limits the incurred latency and overhead. In TARANET's setup phase, traffic analysis is thwarted by mixing. In the data transmission phase, end hosts and ASes coordinate to shape traffic into constant-rate transmission using packet splitting. Our prototype implementation shows that TARANET can forward anonymous traffic at over 50 Gbps using commodity hardware.
Recent research @cite_50 @cite_43 @cite_70 proposes that incorporate anonymous communication as a service of network infrastructures in the Internet and next generation network architectures @cite_39 @cite_55 @cite_69 . The basic assumption of a network-layer anonymity system is that Autonomous Systems (AS) can conduct efficient cryptographic operations when forwarding packets to conceal forwarding information. Additionally, a network-layer anonymity system uses direct forwarding paths rather than reroute packets through overlay networks as in Tor @cite_14 . This processing would be done on (software) routers, for instance, but more abstractedly the term is used to refer to the device or set of devices dedicated to the anonymity system within an AS.
@cite_69 @cite_14 @cite_70 @cite_55 @cite_39 @cite_43 @cite_50
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Popular anonymous communication systems often require sending packets through a sequence of relays on dilated paths for strong anonymity protection. As a result, increased end-to-end latency renders such systems inadequate for the majority of Internet users who seek an intermediate level of anonymity protection while using latency-sensitive applications, such as Web applications. This paper serves to bridge the gap between communication systems that provide strong anonymity protection but with intolerable latency and non-anonymous communication systems by considering a new design space for the setting. More specifically, we explore how to achieve near-optimal latency while achieving an intermediate level of anonymity with a weaker yet practical adversary model (i.e., protecting an end-host's identity and location from servers) such that users can choose between the level of anonymity and usability. We propose Lightweight Anonymity and Privacy (LAP), an efficient network-based solution featuring lightweight path establishment and stateless communication, by concealing an end-host's topological location to enhance anonymity against remote tracking. To show practicality, we demonstrate that LAP can work on top of the current Internet and proposed future Internet architectures. As more of our daily activities are carried out online, it becomes important to develop technologies to protect our online privacy. Anonymity is a key privacy technology, since it serves to hide patterns of communication that can often be as revealing as their contents. This motivates our study of the use of large scale peer-to-peer systems for building anonymous systems. We first develop a novel methodology for studying the anonymity of peer-to-peer systems, based on an information-theoretic anonymity metric and simulation. We use simulations to sample a probability distribution modeling attacker knowledge under conservative assumptions and estimate the entropy-based anonymity metric using the sampled distribution. We then validate this approach against an analytic method for computing entropy. The use of sampling introduces some error, but it can be accurately bounded and therefore we can make rigorous statements about the success of an entire class of attacks. We next apply our methodology to perform the first rigorous analysis of Freenet, a peer-to-peer anonymous publishing system, and identify a number of weaknesses in its design. We show that a targeted attack on high-degree nodes can be very effective at reducing anonymity. We also consider a next generation routing algorithm proposed by the Freenet authors to improve performance and show that it has a significant negative impact on anonymity. Finally, even in the best case scenario, the anonymity levels provided by Freenet are highly variable and, in many cases, little or no anonymity is achieved. To provide more uniform anonymity protection, we propose a new design for peer-to-peer anonymous systems based on structured overlays. We use random walks along the overlay to provide anonymity. We compare the mixing times of random walks on different graph structures and find that de Bruijn graphs are superior to other structures such as the hypercube or butterfly. Using our simulation methodology, we analyze the anonymity achieved by our design running on top of Koorde, a structured overlay based on de Bruijn graphs. We show that it provides anonymity competitive with Freenet in the average case, while ensuring that worst-case anonymity remains at an acceptable level. We also maintain logarithmic guarantees on routing performance. Peer-to-peer approaches to anonymous communication promise to eliminate the scalability concerns and central vulnerability points of current networks such as Tor. However, the P2P setting introduces many new opportunities for attack, and previous designs do not provide an adequate level of anonymity. We propose ShadowWalker: a new low-latency P2P anonymous communication system, based on a random walk over a redundant structured topology. We base our design on shadows that redundantly check and certify neighbor information; these certifications enable nodes to perform random walks over the structured topology while avoiding route capture and other attacks. We analytically calculate the anonymity provided by ShadowWalker and show that it performs well for moderate levels of attackers, and is much better than the state of the art. We also design an extension that improves forwarding performance at a slight anonymity cost, while at the same time protecting against selective DoS attacks. We show that our system has manageable overhead and can handle moderate churn, making it an attractive new design for P2P anonymous communication. The ability to locate random relays is a key challenge for peer-to-peer (P2P) anonymous communication systems. Earlier attempts like Salsa and AP3 used distributes hash table lookups to locate relays, but the lack of anonymity in their lookup mechanisms enables an adversary to infer the path structure and compromise used anonymity. NISAN and Torsk are state-of-the-art systems for P2P anonymous communication. Their designs include mechanisms that are specifically tailored to mitigate information leak attacks. NISAN proposes to add anonymity into the lookup mechanism itself, while Torsk proposes the use of secret buddy nodes to anonymize the lookup initiator. In this paper, we attack the key mechanisms that hide the relationship between a lookup initiator and its selected relays in NISAN and Torsk. We present passive attacks on the NISAN lookup and show that it is not as anonymous as previously thought. We analyze three circuit construction mechanisms for anonymous communication using the NISAN lookup, and show that the information leaks in the NISAN lookup lead to a significant reduction in user anonymity. We also propose active attacks on Torsk that defeat its secret buddy mechanism and consequently compromise user anonymity. Our results are backed up by probabilistic modeling and extensive simulations. Our study motivates the search for a DHT lookup mechanism that is both secure and anonymous.