Persistent Stochastic Non-Interference

In this paper, we study an information flow security property for systems specified as terms of a quantitative Markovian process algebra, namely the Performance Evaluation Process Algebra (PEPA). We propose extension Non-Interference used to secure from functional point view by assuming that observers are able measure also timing properties system, e.g., response time certain actions or its throughput. introduce notion Persistent Stochastic (PSNI) based on idea every state reachable satisfies basic (SNI) property. The structural operational semantics PEPA allows us give two characterizations PSNI: one bisimulation-like equivalence relation inducing lumping underlying Markov chain, and another unwinding conditions which demand individual actions. These different naturally lead efficient methods verification construction systems. A decision algorithm PSNI is presented application queueing system discussed.