Secure Key-Updating for Lazy Revocation

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Secure Key-Updating for Lazy Revocation
Abstract. We consider the problem of efficient key management and user revocation in cryptographic file systems that allow shared access to files. A performanceefficient solution to user revocation in such systems is lazy revocation, a method that delays the re-encryption of a file until the next write to that file. We formalize the notion of key-updating schemes for lazy revocation, an abstraction to manage cryptographic keys in file systems with lazy revocation, and give a security definition for such schemes. We give two composition methods that combine two secure key-updating schemes into a new secure scheme that permits a larger number of user revocations. We prove the security of two slightly modified existing constructions and propose a novel binary tree construction that is also provably secure in our model. Finally, we give a systematic analysis of the computational and communication complexity of the three constructions and show that the novel construction improves the previo...
Michael Backes, Christian Cachin, Alina Oprea
Added 22 Aug 2010
Updated 22 Aug 2010
Type Conference
Year 2006
Authors Michael Backes, Christian Cachin, Alina Oprea
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