| | |
Summary: On the Extension of Non-interference with Probabilities
Alessandro Aldini
Universita di Bologna, Dipartimento di Scienze dell'Informazione
Mura Anteo Zamboni 7, 40127 Bologna, Italy, e-mail: aldini@cs.unibo.it
Abstract
We present a probabilistic extension of the classi cation of security properties for the information
ow analysis of computer systems. In particular, by employing a process algebraic approach we show
that the classical results known from the non-interference theory based on nondeterminism (like e.g. the
inclusion relationship among the di erent properties) are preserved when passing to the probabilistic
setting. Moreover, we show the consistency of our approach by proving that systems which satisfy a
probabilistic security property continue to be secure with respect to the same property de ned in the
nondeterministic setting.
1 Introduction
The use of process algebras for the formalization of non-interference in information
ow analysis [10] is a
well established approach employed for the veri cation of the non-occurrence of unauthorized disclosure of
con dential information [12, 18, 6, 17, 19]. As an example, the authors of [6] introduce an extension of
CCS [16] where the events are partitioned into two di erent levels of con dentiality (low level and high
level), and they propose a classi cation of a set of properties capturing the idea of non-interference together
with an analysis of the kind of information
ow from high level to low level that each property can reveal.
The security properties for nondeterministic processes de ned in the works cited above are often more
|
