\title{A Notion of Non-Interference for Timed Automata}

\author{Roberto Barbuti \and Nicoletta De Francesco \and Antonella
Santone \and Luca Tesei}

\begin{abstract} 
The non-interference property of concurrent systems is a security
property concerning the flow of information among different levels of
security of the system.  If we suppose that the behavior of the system
is divided into a high security behavior and low security behavior, we
say that the system respects the non-interference property if the
low-level behavior is not affected by the high-level one.  In this
paper we discuss a notion of non-interference for real-time systems,
where the time is a crucial parameter.  We represent these systems by
timed automata.  The non-interference notion we define depends on a
number $n$ representing a minimum delay between high-level actions
such that the system meets the above desired behavior. Thus our
non-interference notion is parametric with respect to time delays
between high-level actions.  
\end{abstract}