Hierarchical Identity-Based Access Control System

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By Jyh-haw yeh Department of Computer Science Boise State University

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Access ControlControlling data accesses within a networked enterprise, based on security needs. Define access control policy User authentication Policy enforcement mechanisms Data transmission through networks

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Identity-Based Access Control (IBAC)Authentication is based on user’s identity, rather than network connection port. User identity/job duty, time and location of connection – define a set of security groups Different groups have different access privileges on objects. Each object has an access control list (ACL) as an enforcing mechanism.

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Deficiency Observation of IBACSecurity groups have no relationship among them – require duplicate administrative work (See Figure 1) Use different keys for authentication (master key) and authorization (session key). Require a new session key for each access session. Session key generation and distribution may slow down performance.

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Administrative WorkFigure 1: HIBAC versus IBAC (a) Privilege assignment (b) User assignment (c) ACL for an Object IBAC HIBACG1G2G3G1G2G3G1G2G3G3G1G2

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Hierarchical Identity-Based Access Control (HIBAC)Define Security groups to have a hierarchical privilege-inheritance relationship. A group A inherits privileges from a group B if A is located higher than B in the hierarchy. A single mechanism, hierarchical key assignment, for authentication and authorization.

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HIBAC, continue…Why hierarchical? Reduce administrative work. Simplify authentication and authorization logics – single hierarchical key V.S. master & session keys The hierarchical key can also be used for data encryption during transmission.

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A Walk through ExampleA xyz company defines 6 security groups, based on job duty, time and location of network connection. CEO, Finance (FIN), Human Resource (HR), Employee (E), Employee Restricted (ER) and Guest (G). Table 1 specifies the access right assignment. Form a hierarchical policy (See Figure 2).

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A Walk through ExampleTable 1: Access right assignment in a xyz company

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A Walk through ExampleFigure 2: Hierarchical policy and it’s hierarchical key assignment CEO: K1 / \ FIN: K2 HR: K3 \ / E: K4 | ER: K5 | G: K6

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A Walk through ExampleAuthentication: Alice has it’s own hierarchical key, say K2. Alice login networks through an authentication (AE) server. Challenge-and-response between Alice’s machine and AE server. Alice uses K2 (or K5, if public location) to encrypt response to server – prove the security group FIN (or ER) she belongs to.

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A Walk through ExampleAuthentication: After authentication, AE server create a signed proof P to Alice and authorization (AO) server. The proof P may contain

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A Walk through ExampleAuthorization: Alice makes an access request to AO server, with P attached. AO server verifies P and thus authenticate Alice. Based on P, AO server either grants or denies the access.

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A Walk through ExampleData transmission: If AO server grants access to Alice, AO server can use either K2 or K5 to encrypt data and transmits it to Alice. Upon receiving data, Alice uses either K2 or K5 to decrypt data.

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Research ChallengesDesign issues:  Guidelines for defining a hierarchical policy  session key vs. hierarchical key  Minimum contents of P  Prevent the re-use of P – freshness data, revocation of P Figure 1 shows the advantage of reducing administrative work in HIBAC – need quantitative measurement.

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Research ChallengesThe walk through example show the simple logic for authentication and authorization processes in HIBAC – need an event-driven simulation to measure the system performance, in terms of increased control messages and storage. Investigate any unnoticed security vulnerability of the new system.

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Last Updated: 8th March 2018

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