Information Flow in Credential Systems
- Mo Becker
23rd IEEE Computer Security Foundations Symposium (CSF) |
Published by IEEE
This paper proposes a systematic study of information flow in credential-based declarative authorization policies. It argues that a treatment in terms of information flow is needed to adequately describe, analyze and mitigate a class of probing attacks which allow an adversary to infer any confidential fact within a policy. Two information flow properties that have been studied in the context of state transition systems, non-interference and opacity, are reformulated in the current context of policy languages. A comparison between these properties reveals that opacity is the more useful, and more general of the two; indeed, it is shown that non-interference can be stated in terms of opacity. The paper then presents an inference system for non-opacity, or detectability, in Datalog-based policies. Finally, a pragmatic method is presented, based on a mild modification of the mechanics of delegation, for preventing a particularly dangerous kind of probing attack that abuses delegation of authority.
© 2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.http://www.ieee.org/