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Unbounded ABE via Bilinear Entropy Expansion, Revisited

Jie Chen 1 Junqing Gong 2, 3 Lucas Kowalczyk 4 Hoeteck Wee 5, 6 
2 ARIC - Arithmetic and Computing
Inria Grenoble - Rhône-Alpes, LIP - Laboratoire de l'Informatique du Parallélisme
5 CASCADE - Construction and Analysis of Systems for Confidentiality and Authenticity of Data and Entities
DI-ENS - Département d'informatique - ENS Paris, CNRS - Centre National de la Recherche Scientifique : UMR 8548, Inria de Paris
Abstract : We present simpler and improved constructions of unbounded attribute-based encryption (ABE) schemes with constant-size public parameters under static assumptions in bilinear groups. Concretely, we obtain: a simple and adaptively secure unbounded ABE scheme in composite-order groups, improving upon a previous construction of Lewko and Waters (Eurocrypt ’11) which only achieves selective security; an improved adaptively secure unbounded ABE scheme based on the k-linear assumption in prime-order groups with shorter ciphertexts and secret keys than those of Okamoto and Takashima (Asiacrypt ’12); the first adaptively secure unbounded ABE scheme for arithmetic branching programs under static assumptions. At the core of all of these constructions is a “bilinear entropy expansion” lemma that allows us to generate any polynomial amount of entropy starting from constant-size public parameters; the entropy can then be used to transform existing adaptively secure “bounded” ABE schemes into unbounded ones.
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Submitted on : Saturday, October 20, 2018 - 1:15:32 AM
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Jie Chen, Junqing Gong, Lucas Kowalczyk, Hoeteck Wee. Unbounded ABE via Bilinear Entropy Expansion, Revisited. EUROCRYPT 2018 - Annual International Conference on the Theory and Applications of Cryptographic Techniques, Apr 2018, Tel Aviv, Israel. pp.503-534, ⟨10.1007/978-3-319-78381-9_19⟩. ⟨hal-01899901⟩



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