Structural non-interference in elementary and trace nets

  • Authors:
  • Nadia Busi;Roberto Gorrieri

  • Affiliations:
  • Università di bologna, dipartimento di scienze dell'informazione, mura anteo zamboni 7, 40127 bologna, italy email: gorrieri@cs.unibo.it;Università di bologna, dipartimento di scienze dell'informazione, mura anteo zamboni 7, 40127 bologna, italy email: gorrieri@cs.unibo.it

  • Venue:
  • Mathematical Structures in Computer Science
  • Year:
  • 2009

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Abstract

Several notions of non-interference have been proposed in the literature for studying the problem of confidentiality in concurrent systems. The common feature of these non-interference properties is that they are all defined as extensional properties based on some notion of behavioural equivalence on systems. Here, instead, we address the problem of defining non-interference by looking at the structure of the systems under investigation. We use a simple class of Petri nets, namely, contact-free elementary net systems, as the system model and define structural non-interference properties based on the absence of particular places in the net: such places show that a suitable causality or conflict relation is present between a high-level transition and a low-level one. We characterise one structural property, called PBNI+, which we show to be equivalent to the well-known behavioural property SBNDC. It essentially captures all the positive information flows (that is, a low-level user can deduce that some high-level action has occurred). We start by providing a characterisation of PBNI+ on contact-free elementary net systems, then extend the definition to cope with the richer class of trace nets.