Dynamic and Efficient Key Management for Access Hierarchies

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Marina Blanton - Purdue University

Mar 08, 2006

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Abstract

Hierarchies arise in the context of access control whenever the set of users
can be modeled as a set of partially ordered classes (i.e., represented as a
directed graph). In such systems, a user that belongs to a particular class
inherits privileges of all of its descendant classes. The problem of key
management for an access hierarchy then consists in assigning a key to each
class in the hierarchy so that keys for descendant classes can be obtained
via an efficient key derivation process.

We propose an efficient solution to this problem with a number of important
properties, some of which are: a single key per class, local handling of
changes to the hierachy, and provable security against collusion. Whereas
many previous schemes had some of these properties, ours is the first that
satisfies all of them. In addition, we give techniques to exponentially
lower key derivation time for trees with only a contant increase in the
space to store the hierarchy.

About the Speaker

Marina Blanton is a PhD candidate at Purdue University. She received her MS
in CS from Purdue University in 2004 and MS in EECS from Ohio University in
2002. Her research interests lie in the areas of access control, applied
cryptography, and privacy. More information is available at
http://www.cs.purdue.edu/homes/mbykova.

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