Dennis M. Volpano

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Ensuring secure information ow within programs in the context of multiple sensitivity levels has been widely studied. Especially noteworthy is Denning's work in secure ow analysis and the lattice model [6][7]. Until now, however, the soundness of Denning's analysis has not been established satisfactorily. We formulate Denning's approach as a type system and(More)
Previously, we developed a type system to ensure secure information flow in a sequential, imperative programming language [VSI96]. Program variables are classified as either high or low security; intuitively, we wish to prevent information from flowing from high variables to low variables. Here, we extend the analysis to deal with a multithreaded language.(More)
In previous work [16], we give a type system that guarantees that well-typed multithreaded programs are possibilistically noninterfering. If thread scheduling is probabilistic, however, then well-typed programs may have probabilistic timing channels. We describe how they can be eliminated without making the type system more restrictive. We show that(More)
This paper presents a type system which guarantees that well-typed programs in a procedural programming language satisfy a noninterference security property. With all program inputs and outputs classified at various security levels, the property basically states that a program output, classified at some level, can never change as a result of modifying only(More)
Systems that authenticate a user based on a shared secret (such as a password or PIN) normally allow anyone to query whether the secret is a given value. For example, an ATM machine allows one to ask whether a string is the secret PIN of a (lost or stolen) ATM card. Yet such queries are prohibited in any model whose programs satisfy an information-flow(More)
Conditions are given under which a one-way function can be used safely in a programming language. The security proof involves showing that secrets cannot be leaked easily by any program meeting the conditions unless breaking the one-way function is easy. The result is applied to a password system where passwords are stored in a public file as images under a(More)