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Syverson P.,Center for High Assurance Computer Systems
ACM International Conference Proceeding Series | Year: 2011

Onion routing was invented more than fifteen years ago to separate identification from routing in network communication. Since that time there has been much design, analysis, and deployment of onion routing systems. This has been accompanied by much confusion about what these systems do, what security they provide, how they work, who built them, and even what they are called. Here I give an overview of onion routing from its earliest conception to some of the latest research, including the design and use of Tor, a global onion routing network with about a half million users on any given day. Source


Moskowitz I.S.,Center for High Assurance Computer Systems | Ahmed F.,Johns Hopkins University | Lafferty P.A.,Catholic University of America
International Journal of Computers and Applications | Year: 2010

Using information theory, we show that meaningful amounts of information hidden in the spatial bits surprisingly may survive JPEG compression. We prove these results by showing that information hidden in the lower order bits may be modelled as a noisy communication channel, and show that the channel has non-trivial capacity. Source


Goldschlag D.M.,Trust Digital Inc. | Stubblebine S.G.,Stubblebine Consulting LLC | Syverson P.F.,Center for High Assurance Computer Systems
International Journal of Information Security | Year: 2010

This paper describes various types of commitment functions that maintain a secret for a predictable time delay or until a moderate and predictable amount of computation has occurred. The properties we set out for such functions are based on their usefulness for various applications, such as publicly verifiable lotteries, rather than for cryptologic investigation of the functions. In these lotteries, winners are chosen fairly using only internal information. Since all this information may be published (even before the lottery closes), anyone can do the calculation and therefore verify that the winner was chosen correctly. Since the calculation uses a delaying or similar function, neither ticket purchasers nor the lottery organizer can take advantage of this information. We describe several such lotteries and the security requirements they satisfy, assuming that functions with the properties we state are used. © Springer-Verlag 2009. Source


Paxton N.,Center for High Assurance Computer Systems | Mathews J.,Center for High Assurance Computer Systems
CollaborateCom 2014 - Proceedings of the 10th IEEE International Conference on Collaborative Computing: Networking, Applications and Worksharing | Year: 2015

A translational boundary is any computer network system which performs network address translation in order to act as an intermediary between client requests and server responses. Since boundaries essentially hide networks from the world by acting on their behalf, a sensor monitoring traffic for malicious activity outside of a boundary would attribute the boundary itself as the target of an attack rather than the actual host affected behind the boundary. This challenge is exacerbated inside of tiered network architectures and drives the need for a capability to track network communications across boundaries. While several attempts have been made at addressing this problem space, existing approaches are often difficult to implement or fundamentally problematic. We propose a novel method for tracking communications across boundaries based on the fact that the message being transmitted must remain constant and intact in order for it to be successfully interpreted by a server. The proposed method leverages cryptographic hashing techniques applied towards the application layer payload of network packets from two different perspectives on the network, enabling correlation before and after the packet headers are modified by the boundary. The technique can be implemented atop open source technology on commodity hardware, and provides a stable foundation for building tiered enterprise network architectures with an inherent capability for pinpointing malicious activity. © 2014 ICST. Source


Gorantla S.K.,Urbana University | Kadloor S.,Urbana University | Kiyavash N.,Urbana University | Coleman T.P.,Urbana University | And 2 more authors.
IEEE Transactions on Information Forensics and Security | Year: 2012

The Naval Research Laboratory (NRL) Network Pump, or Pump, is a standard for mitigating covert channels that arise in a multilevel secure (MLS) system when a high user (HU) sends acknowledgements to a low user (LU). The issue here is that HU can encode information in the timings of the acknowledgements. The Pump aims at mitigating the covert timing channel by introducing buffering between HU and LU, as well as adding noise to the acknowledgment timings. We model the working of the Pump in certain situations, as a communication system with feedback and use then this perspective to derive an upper bound on the capacity of the covert channel between HU and LU in the Pump. This upper bound is presented in terms of a directed information flow over the dynamics of the system. We also present an achievable scheme that can transmit information over this channel. When the support of the noise added by Pump to acknowledgment timings is finite, the achievable rate is nonzero, i.e., infinite number of bits can be reliably communicated. If the support of the noise is infinite, the achievable rate is zero and hence a finite number of bits can be communicated. © 2011 IEEE. Source

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