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Citation - WoS: 25
Citation - Scopus: 26
Quantum Key Distribution in the Classical Authenticated Key Exchange Framework
(Springer, 2013) Mosca, Michele; Stebila, Douglas; Ustaoğlu, Berkant
Key establishment is a crucial primitive for building secure channels in a multi-party setting. Without quantum mechanics, key establishment can only be done under the assumption that some computational problem is hard. Since digital communication can be easily eavesdropped and recorded, it is important to consider the secrecy of information anticipating future algorithmic and computational discoveries which could break the secrecy of past keys, violating the secrecy of the confidential channel. Quantum key distribution (QKD) can be used generate secret keys that are secure against any future algorithmic or computational improvements. QKD protocols still require authentication of classical communication, although existing security proofs of QKD typically assume idealized authentication. It is generally considered folklore that QKD when used with computationally secure authentication is still secure against an unbounded adversary, provided the adversary did not break the authentication during the run of the protocol. We describe a security model for quantum key distribution extending classical authenticated key exchange (AKE) security models. Using our model, we characterize the long-term security of the BB84 QKD protocol with computationally secure authentication against an eventually unbounded adversary. By basing our model on traditional AKE models, we can more readily compare the relative merits of various forms of QKD and existing classical AKE protocols. This comparison illustrates in which types of adversarial environments different quantum and classical key agreement protocols can be secure. © 2013 Springer-Verlag.
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: 4
Reusing Static Keys in Key Agreement Protocols
(Springer Verlag, 2009) Chatterjee, Sanjit; Menezes, Alfred; Ustaoğlu, Berkant
Contrary to conventional cryptographic wisdom, the NIST SP 800-56A standard explicitly allows the use of a static key pair in more than one of the key establishment protocols described in the standard. In this paper, we give examples of key establishment protocols that are individually secure, but which are insecure when static key pairs are reused in two of the protocols. We also propose an enhancement of the extended Canetti-Krawczyk security model and definition for the situation where static public keys are reused in two or more key agreement protocols. © 2009 Springer-Verlag.
Citation - WoS: 19
Comparing the Pre- and Post-Specified Peer Models for Key Agreement
(Springer Verlag, 2008) Menezes, Alfred; Ustaoğlu, Berkant
In the pre-specified peer model for key agreement, it is assumed that a party knows the identifier of its intended communicating peer when it commences a protocol run. On the other hand, a party in the post-specified peer model for key agreement does not know the identifier of its communicating peer at the outset, but learns the identifier during the protocol run. In this paper we compare the security assurances provided by the Canetti-Krawczyk security definitions for key agreement in the pre- and post-specified peer models. We give examples of protocols that are secure in one model but insecure in the other. We also enhance the Canetti-Krawczyk security models and definitions to encompass a class of protocols that are executable and secure in both the pre- and post-specified peer models. © 2008 Springer-Verlag Berlin Heidelberg.

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