Modelling a Fuzzy Time System

Article type: Research Article

Authors: Trostle, Jonathan T.^{1; 2}

Affiliations: The MITRE Corporation, 202 Burlington Road, Bedford, MA 01730-1420, USA

Correspondence: [2] Correspondence to: J.T. Trostle, 408 Katahdin Drive, Lexington, MA 02173, USA. E-mail: [email protected].

Note: [1] This work was supported by the Rome Air Development Center under Contract F19628-89-C-000l and completed under MITRE Project 4030.

Abstract: We analyze the DEC fuzzy time technique (Hu [HU]) for both a single computer system and a network of hosts. Specifically, we investigate covert channels in a model of a fuzzy time system and in a network model of n fuzzy time hosts and one nonfuzzy time host. The fuzzy time operating system model predicts a covert channel with a datarate of roughly 50 bits per second, given a mean time between upticks of 20 milliseconds as in the VAX security kernel. We suggest several countermeasures including scheduler redesign which will close or reduce the channels that we analyze.

DOI: 10.3233/JCS-1993-2403

Journal: Journal of Computer Security, vol. 2, no. 4, pp. 291-309, 1993