Rémi Watrigant

Resiliency Policies in Access Control Revisited

Resiliency is a relatively new topic in the context of access control. Informally, it refers to the extent to which a multi-user computer system, subject to an authorization policy, is able to continue functioning if a number of authorized users are unavailable. Several interesting problems connected to resiliency were introduced by Li, Wang and Tripunitara [13], many of which were found to be intractable. In this paper, we show that these resiliency problems have unexpected connections with the workflow satisfiability problem (WSP). In particular, we show that an instance of the resiliency checking problem (RCP) may be reduced to an instance of WSP. We then demonstrate that recent advances in our understanding of WSP enable us to develop fixed-parameter tractable algorithms for RCP. Moreover, these algorithms are likely to be useful in practice, given recent experimental work demonstrating the advantages of bespoke algorithms to solve WSP. We also generalize RCP in several different ways, showing in each case how to adapt the reduction to WSP. Li et al also showed that the coexistence of resiliency policies and static separation-of-duty policies gives rise to further interesting questions. We show how our reduction of RCP to WSP may be extended to solve these problems as well and establish that they are also fixed-parameter tractable.

A Multivariate Approach for Checking Resiliency in Access Control

In recent years, several combinatorial problems were introduced in the area of access control. Typically, such problems deal with an authorization policy, seen as a relation

On the Satisfiability of Workflows with Release Points

UR \subseteq U \times R

Parameterized Resiliency Problems via Integer Linear Programming

, where

Complexity Dichotomies for the Minimum \(\mathcal {F}\)-Overlay Problem

(u, r) \in UR

An Approach to Parameterized Resiliency Problems Using Integer Linear Programming.

means that user

The bi-objective workflow satisfiability problem and workflow resiliency 1

u

Complexity Dichotomies for the Minimum F-Overlay Problem

is authorized to access resource

Comparaison de deux clusterings par couplage entre clusters de clusters

r

The Authorization Policy Existence Problem

. Li, Tripunitara and Wang (2009) introduced the Resiliency Checking Problem (RCP), in which we are given an authorization policy, a subset of resources