200 research outputs found
Proof Theory, Transformations, and Logic Programming for Debugging Security Protocols
We define a sequent calculus to formally specify, simulate, debug and verify security protocols. In our sequents we distinguish between the current knowledge of principals and the current global state of the session. Hereby, we can describe the operational semantics of principals and of an intruder in a simple and modular way. Furthermore, using proof theoretic tools like the analysis of permutability of rules, we are able to find efficient proof strategies that we prove complete for special classes of security protocols including Needham-Schroeder. Based on the results of this preliminary analysis, we have implemented a Prolog meta-interpreter which allows for rapid prototyping and for checking safety properties of security protocols, and we have applied it for finding error traces and proving correctness of practical examples
Integration of analysis techniques in security and fault-tolerance
This thesis focuses on the study of integration of formal methodologies in security protocol analysis and fault-tolerance analysis. The research is developed in two different directions: interdisciplinary and intra-disciplinary. In the former, we look for a beneficial interaction between strategies of analysis in security protocols and fault-tolerance; in the latter, we search for connections among different approaches of analysis within the security area. In the following we summarize the main results of the research
Relating process languages for security and communication correctness (extended abstract)
Process calculi are expressive specification languages for concurrency. They have been very successful in two research strands: (a) the analysis of security protocols and (b) the enforcement of correct message-passing programs. Despite their shared foundations, languages and reasoning techniques for (a) and (b) have been separately developed. Here we connect two representative calculi from (a) and (b): we encode a (high-level) Ļ-calculus for multiparty sessions into a (low-level) applied Ļ-calculus for security protocols. We establish the correctness of our encoding, and we show how it enables the integrated analysis of security properties and communication correctness by re-using existing tools
Relating Multiset Rewriting and Process Algebras for Security Protocol Analysis
When formalizing security protocols, different specification languages support very different reasoning methodologies, whose results are not directly or easily comparable. Therefore, establishing clear mappings among different frameworks is highly desirable, as it permits various methodologies to cooperate by interpreting theoretical and practical results of one system into another. In this paper, we examine the relationship between two general verification frameworks: multiset rewriting (MSR) and a process algebra (PA) inspired to CCS and the -calculus. Although defining a simple and general bi-jection between MSR and PA appears difficult, we show that the sublanguages needed to specify cryptographic protocols admit an effective translation that is not only trace-preserving, but also induces a correspondence relation between the two languages. In particular, the correspondence sketched in this paper permits transferring several important trace-based properties such as secrecy and many forms of authentication
Security Theorems via Model Theory
A model-theoretic approach can establish security theorems for cryptographic
protocols. Formulas expressing authentication and non-disclosure properties of
protocols have a special form. They are quantified implications for all xs .
(phi implies for some ys . psi). Models (interpretations) for these formulas
are *skeletons*, partially ordered structures consisting of a number of local
protocol behaviors. Realized skeletons contain enough local sessions to explain
all the behavior, when combined with some possible adversary behaviors. We show
two results. (1) If phi is the antecedent of a security goal, then there is a
skeleton A_phi such that, for every skeleton B, phi is satisfied in B iff there
is a homomorphism from A_phi to B. (2) A protocol enforces for all xs . (phi
implies for some ys . psi) iff every realized homomorphic image of A_phi
satisfies psi. Hence, to verify a security goal, one can use the Cryptographic
Protocol Shapes Analyzer CPSA (TACAS, 2007) to identify minimal realized
skeletons, or "shapes," that are homomorphic images of A_phi. If psi holds in
each of these shapes, then the goal holds
Towards the Correctness of Security Protocols
AbstractIn [19], the authors presented a type-theoretic approach to the verification of security protocols. In this approach, a universal type system is proposed to capture in a finite way all the possible computations (internal actions or protocol instrumentations) that could be performed by a smart malicious intruder. This reduces the verification of cryptographic protocols to a typing problem where types are attack scenarios. In this paper, we recall this type system and we prove its completeness i.e. if the intruder can learn a message from a given protocol instrumentation, then this message could be infered from the type system. A significant result of this paper is the presentation of a new transformation that allows us to abstract a non-terminating type inference system into a terminating deductive proof system. We demonstrate how these results could be used to establish the security of cryptographic protocols from the secrecy standpoint. Finally, the usefulness and the efficiency of the whole approach is illustrated by proving the correctness of a new version of the Needham-Shoreder protocol with respect to the secrecy property
A Multiset Rewriting Model for Specifying and Verifying Timing Aspects of Security Protocols
Catherine Meadows has played an important role in the advancement of formal methods for protocol security verification. Her insights on the use of, for example, narrowing and rewriting logic has made possible the automated discovery of new attacks and the shaping of new protocols. Meadows has also investigated other security aspects, such as, distance-bounding protocols and denial of service attacks. We have been greatly inspired by her work. This paper describes the use of Multiset Rewriting for the specification and verification of timing aspects of protocols, such as network delays, timeouts, timed intruder models and distance-bounding properties. We detail these timed features with a number of examples and describe decidable fragments of related verification problems
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