1,721,077 research outputs found
Classification of Security Properties (Part I: Information Flow)
No full textIn the recent years, many formalizations of security properties have been proposed, most of which are based on different underlying models and are consequently difficult to compare. A classification of security properties is thus of interest for understanding the relationships among different definitions and for evaluating the relative merits. In this paper, many non-interference-like properties proposed for computer security are classified and compared in a unifying framework. The resulting taxonomy is evaluated through some case studies of access control in computer systems. The approach has been mechanized, resulting in the tool CoSeC. Various extensions (e.g., the application to cryptographic protocol analysis) and open problems are discussed
Distributed Logic Programming
No full textWe present a model for distributed logic programming based on ANDparallelism and on explicit message-passing primitives. The communication mechanism is inspired by Milner's CCS [31]. First, a simple calculus of communicating sequential logic processes is defined to formally introduce this notion of communication in a logic programming setting. Then, the definition of the language is completed by extending the calculus with an alternative command, as well as with mechanisms for the dynamic creation of AND-parallel processes. The resulting language is a variant of Distributed Logic defined by Monteiro [33].
The second part of the paper focuses on the study of the semantics of the language. We define a model-theoretic semantics by providing the various goal composition operators and the communication primitives with a clear logical meaning. On the other hand, an operational semantics is given in terms of the distributed model of Petri nets. The latter characterization is shown to provide several insights on the programming language, such as the ability of capturing fairness and liveness properties.
The study of the semantics terminates with the proof of the equivalence (soundness and completeness) between the model-theoretic and the operational semantics
A Study About Trade-off Between Performance and Security in an Internet Audio Mechanism
No full textWe study the nature of the relationship between performance measures and privacy guarantees in the case study of an adaptive protocol for the secure transmission of real-time audio over the Internet. The analysis is conducted on a process-algebraic description of the audio mechanism by following a methodology that allows the modeler to (i) employ the noninterference approach to information flow theory for the analysis of security requirements, and (ii) derive performance measures obtained through markovian analysis techniques. The main result we present is that the analysis of performance properties helps to estimate the effectiveness (and to find a related countermove) of an attack that is captured by the security analysis
On Intransitive Non-interference in Some Models of Concurrency
No full textIntransitive non-interference (INI for short) is a behavioural property extensively studied by Rushby over deterministic automata with outputs associated to transitions (Mealy machines) in order to discuss the security of systems where declassification of secret information is allowed.
In this paper, we first propose a natural transposition of Rushby's definition on deterministic labelled transition systems, we call INI as well, and then an alternative, yet more easily checkable, formulation of INI, called {em NI with downgraders} (NID for short). We show how NID can be naturally extended to the case of nondeterministic automata by using a variation of it based on bisimulation equivalence (BNID).
The most novel contribution of this paper is the extension of this theory on the class of Petri nets called elementary net systems: we propose a semi-static technique, called PBNID and based on the inspection of the net structure, that is shown to be equivalent to BNID
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