Freenet is a popular peer to peer anonymous content-sharing network, with the objective to provide the anonymity of both content publishers and retrievers. Despite more than a decade of active development and deployment and the adoption of well-established cryptographic algorithms in Freenet, it remains unanswered how well the anonymity objective of the initial Freenet design has been met. In this paper we develop a traceback attack on Freenet, and show that the originating machine of a content request message in Freenet can be identified; that is, the anonymity of a content retriever can be broken, even if a single request message has been issued by the retriever. We present the design of the traceback attack, and perform both experimental and simulation studies to confirm the feasibility and effectiveness of the attack. For example, with randomly chosen content requesters (and random contents stored in the Freenet testbed), Emulab-based experiments show that, for$24$to$43$percent of the content request messages, we can identify their originating machines. We also briefly discuss potential solutions to address the developed traceback attack. Despite being developed specifically on Freenet, the basic principles of the traceback attack and solutions have important security implications for similar anonymous content-sharing systems.

Abstract The emerging smart grid incorporates modern information systems with traditional power delivery systems to achieve better control, efficiency, and reliability. However, it also brings potential cyber security risks into the essential power system. Therefore, we need a large‐scale framework to address the basic security issues such as identity management in the smart grid. While public key infrastructures (PKIs) have been developed for large‐scale distributed information systems, the existing PKI solutions cannot meet the unique requirements of the electrical power grid. In this paper, we first identify those unique requirements and discuss how the existing PKI trust models may be adapted to meet these requirements; we further evaluate the existing certificate revocation models; we then discuss various PKI adaptations for the smart grid. Copyright © 2014 John Wiley & Sons, Ltd.

As privacy becomes an increasingly important issue on today's Internet, attacks on anonymous tools gain more attention. In this paper, we investigated countermeasures to a routing table insertion (RTI) attack on Freenet. We analyzed the key factors supporting the RTI attack, and proposed a simple randomized routing method to mitigate the RTI or similar attacks. We implemented the proposed method on the Freenet Thynix simulator. Our results show that the proposed method works well on small world topologies and thus a feasible choice to deal with the RTI attack on Freenet. We are further investigating more effective countermeasures based on these results.

A traceback attack was recently developed on Freenet, which can identify the originating machine of a content request message, even if a single content request message has been issued by a content retriever. The traceback attack exploited a few fine-grained design and development decisions made in Freenet, including the unique identifier (UID) based mechanism to prevent routing loops of content request messages. In this paper we develop a simple yet effective scheme named dynID to thwart the traceback attack on Freenet. In dynID, the UID associated with a content request message is dynamically changed at the beginning portion of the message forwarding path. As a consequence, an attacker can only trace back a content request message to the node where the UID value is last changed; it cannot uniquely determine the originating machine of the message. Importantly, dynID only has negligible impacts on the performance of Freenet in locating content on the network. For example, our simulation studies based on the original Freenet source code show that, for all content requests, we can successfully locate the corresponding requested content.

Freenet is a popular peer to peer anonymous network, with the objective to provide the anonymity of both content publishers and retrievers. Despite more than a decade of active development and deployment and the adoption of well-established cryptographic algorithms in Freenet, it remains unanswered how well the anonymity objective of the initial Freenet design has been met. In this paper we develop a traceback attack on Freenet, and show that the originating machine of a content request message in Freenet can be identified; that is, the anonymity of a content retriever can be broken, even if a single request message has been issued by the retriever. We present the design of the traceback attack, and perform Emulab-based experiments to confirm the feasibility and effectiveness of the attack. With randomly chosen content requesters (and random contents stored in the Freenet testbed), the experiments show that, for 24% to 43% of the content request messages, we can identify their originating machines. We also briefly discuss potential solutions to address the developed traceback attack. Despite being developed specifically on Freenet, the basic principles of the traceback attack and solutions have important security implications for similar anonymous content sharing systems.