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We consider expansions of the Abadi-Rogaway logic of indistinguishability of formal cryptographic expressions. We expand the logic in order to cover cases when partial information of the encrypted plaintext is revealed. We consider not only computational, but also purely probabilistic, information-theoretic interpretations. We present a general, systematic(More)
In the investigation of the relationship between the formal and the computational view of cryptography, a recent approach, first proposed in [10], uses static equivalence from cryptographic pi calculi as a notion of formal indistinguishability. Previous work [10, 1] has shown that this yields the soundness of natural interpretations of some interesting(More)
We consider the question of the adequacy of symbolic models versus computational models for the verification of security protocols. We neither try to include properties in the symbolic model that reflect the properties of the computational primitives nor add computational requirements that enforce the sound-ness of the symbolic model. We propose in this(More)
In their seminal work, Abadi and Rogaway [2, 3] show that the formal (Dolev-Yao) notion of indistinguishability is sound with respect to the computational model: messages that are indistinguishable in the formal model become indistinguishable messages in the computational model. However, this result leaves two problems unsolved. First, it cannot tolerate(More)
We present a computationally sound first-order system for security-analysis of protocols that places secrecy of nonces and keys in its center. Even trace properties such as agreement and authentication are proven via proving a non-trace property, namely, secrecy first with an induc-tive method. This results a very powerful system, the working of which we(More)
Acknowledgements I would like to thank Andre Scedrov for his tremendous support as a thesis advisor, and also for introducing me to the subject and to the information security and cryptography community. I would also like to thank Pedro Adão from the University of Lisbon for the great hours of research we spent on the subject, and for reading the manuscript(More)
Recently, Bana and Comon-Lundh introduced the notion of computationally complete symbolic attacker to deliver unconditional computational soundness to symbolic protocol verification. First we explain the relationship between their technique and Fitting's embedding of classical logic into S4. Then, based on predicates for "key usability", we provide an(More)
We show that the recent technique of computationally complete symbolic attackers proposed by Bana and Comon-Lundh [6] for computationally sound verification of security protocols is powerful enough to verify actual protocols. In their work, Bana and Comon-Lundh presented only the general framework, but they did not introduce sufficiently many axioms to(More)
We consider the problem of computational indistinguishability of protocols. We design a symbolic model, amenable to automated deduction, such that a successful inconsistency proof implies computational indistinguishability. Conversely, symbolic models of distinguishability provide clues for likely computational attacks. We follow the idea we introduced(More)