Approximate non-interference

Issue title: Special issue on WITS'02

Guest editors: Joshua Guttman

Article type: Research Article

Authors: Di Pierro, Alessandra^{a; *} | Hankin, Chris^b | Wiklicky, Herbert^b

Affiliations: [a] Dipartimento di Informatica, Università di Pisa, Italy. E-mail: [email protected] | [b] Department of Computing, Imperial College London, UK. E-mail: [email protected], [email protected]

Correspondence: [*] Corresponding author: Alessandra Di Pierro, Dipartimento di Informatica, Università di Pisa, Via F. Buonarroti, 2, 56127 Pisa, Italy. Tel.: +39 05 02212779; Fax: +39 05 02212726; E-mail: [email protected].

Abstract: We address the problem of characterising the security of a program against unauthorised information flows. Classical approaches are based on non-interference models which depend ultimately on the notion of process equivalence. In these models confidentiality is an absolute property stating the absence of any illegal information flow. We present a model in which the notion of non-interference is approximated in the sense that it allows for some exactly quantified leakage of information. This is characterised via a notion of process similarity which replaces the indistinguishability of processes by a quantitative measure of their behavioural difference. Such a quantity is related to the number of statistical tests needed to distinguish two behaviours. We also present two semantics-based analyses of approximate non-interference and we show that one is a correct abstraction of the other.

DOI: 10.3233/JCS-2004-12103

Journal: Journal of Computer Security, vol. 12, no. 1, pp. 37-81, 2004