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Citation - WoS: 22
Anonymity and One-Way Authentication in Key Exchange Protocols
(Springer Verlag, 2013) Goldberg, Ian; Stebila, Douglas; Ustaoğlu, Berkant
Key establishment is a crucial cryptographic primitive for building secure communication channels between two parties in a network. It has been studied extensively in theory and widely deployed in practice. In the research literature a typical protocol in the public-key setting aims for key secrecy and mutual authentication. However, there are many important practical scenarios where mutual authentication is undesirable, such as in anonymity networks like Tor, or is difficult to achieve due to insufficient public-key infrastructure at the user level, as is the case on the Internet today. In this work we are concerned with the scenario where two parties establish a private shared session key, but only one party authenticates to the other; in fact, the unauthenticated party may wish to have strong anonymity guarantees. We present a desirable set of security, authentication, and anonymity goals for this setting and develop a model which captures these properties. Our approach allows for clients to choose among different levels of authentication. We also describe an attack on a previous protocol of Øverlier and Syverson, and present a new, efficient key exchange protocol that provides one-way authentication and anonymity. © 2012 Springer Science+Business Media, LLC.
Citation - WoS: 22
Multi-Party Off-The Messaging
(Association for Computing Machinery (ACM), 2009) Goldberg, Ian; Ustaoğlu, Berkant; Van Gundy, Matthew D.; Chen, Hao
Most cryptographic algorithms provide a means for secret and authentic communication. However, under many circumstances, the ability to repudiate messages or deny a conversation is no less important than secrecy and authenticity. For whistleblowers, informants, political dissidents and journalists - to name a few - it is most important to have means for deniable conversation, where electronic communication must mimic face-to-face private meetings. Off-the-Record Messaging, proposed in 2004 by Borisov, Goldberg and Brewer, and its subsequent improvements, simulate private two-party meetings. Despite some attempts, the multi-party scenario remains unresolved. In this paper, we first identify the properties of multi-party private meetings. We illustrate the differences not only between the physical and electronic medium but also between two- and multi-party scenarios, which have important implications for the design of private chatrooms. We then propose a solution to multi-party off-the-record instant messaging that satisfies the above properties. Our solution is also composable with extensions that provide other properties, such as anonymity. Copyright 2009 ACM.

Mathematics / Matematik

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