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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

We consider a calculus for multiparty sessions with delegation, enriched with security levels for session participants and data. We propose a type system that guarantees both session safety and a form of access control. Moreover, this type system ensures secure information flow, including controlled forms of declassification. In particular, it prevents information leaks due to the specific control constructs of the calculus, such as session opening, selection, branching and delegation. We illustrate the use of our type system with a number of examples, which reveal an interesting interplay between the constraints of security type systems and those used in session types to ensure properties like communication safety and session fidelity.

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Abstract.We introduce an algebra of labelled event structures whose operations are sequential composition, sum, and parallel composition. A transition relation is defined on these objects, where at each step a process performs a labelled poser. It is claimed that the bisimulation relative to such transition systems brings out a clean distinction between concurrency and sequential non-determinism.