Unlinkability through Access Control: Respecting User-Privacy in Distributed Systems

Kapadia, Apu C.; Naldurg, Prasad G.; Campbell, Roy H.

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https://hdl.handle.net/2142/11086 Copy

Description

Title

Unlinkability through Access Control: Respecting User-Privacy in Distributed Systems

Author(s)

• Kapadia, Apu C.
• Naldurg, Prasad G.
• Campbell, Roy H.

Issue Date

2005-08

Keyword(s)

• computer science
• distributed systems

Abstract

We propose a policy-based framework using RBAC (Role Based Access Control) to address the unlinkability problem in the context of correlating audit records generated from access to distributed services. We explore this problem in an environment where the enforcement of access control policies is decentralized and ensuring policy consistency as the protection state of the system evolves becomes important. We introduce the notion of an audit flow associated with a user's access transactions, which represents the flow of information through audit logs within an administrative domain. Users of our system can present a set of audit flows to a decision engine that uses global access rules to detect potential linkability conflicts. Users can use this information to specify discretionary unlinkability requirements, depending on whether these accesses can expose sensitive attributes. We present an algorithm that can generate policy constraints based on these discretionary requirements. We also show how these policy constraints can be attached to individual audit log records to enforce unlinkability in a distributed manner. We prove that our proposed algorithm generates constraints that are secure and precise under strong tranquility assumptions with respect to the system's protection state. When we relax these assumptions, we show how versioning can cope with evolving protection state, trading off precision to maintain the security of deployed policies.

Type of Resource

text

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http://hdl.handle.net/2142/11086

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