Ciphertext-Policy Attribute-Based Encryption

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Ciphertext-Policy Attribute-Based EncryptionJohn BethencourtCarnegie Mellon Sahai Waters SRI several distributed systems a user should only beable to access data if a user posses a certain set of cre-dentials or attributes. Currently, the only method forenforcing such policies is to employ a trusted server tostore the data and mediate access control. However, ifany server storing the data is compromised, then theconfidentiality of the data will be compromised. In thispaper we present a system for realizing complex accesscontrol on encrypted data that we call ciphertext -PolicyAttribute- based Encryption . By using our techniquesencrypted data can be kept confidential even if the stor-age server is untrusted; moreover, our methods aresecure against collusion attacks.

tonic “access tree”, where nodes of the access struc-ture are composed of threshold gates and the leaves describe attributes. We note that AND gates can be constructed as n-of-nthreshold gates and OR gates as 1-of-nthreshold gates. Furthermore, we can handle more complex access controls such as numeric ranges

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