Unbounded ABE via Bilinear Entropy Expansion, Revisited

Jie Chen; Junqing Gong; Lucas Kowalczyk; Hoeteck Wee

Paper 2018/116

Unbounded ABE via Bilinear Entropy Expansion, Revisited

Jie Chen, Junqing Gong, Lucas Kowalczyk, and Hoeteck Wee

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.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: A major revision of an IACR publication in EUROCRYPT 2018
Keywords: attribute-based encryption
Contact author(s): junqing gong @ ens-lyon fr
History: 2018-01-31: received
Short URL: https://ia.cr/2018/116
License: CC BY

BibTeX

@misc{cryptoeprint:2018/116,
      author = {Jie Chen and Junqing Gong and Lucas Kowalczyk and Hoeteck Wee},
      title = {Unbounded {ABE} via Bilinear Entropy Expansion, Revisited},
      howpublished = {Cryptology {ePrint} Archive, Paper 2018/116},
      year = {2018},
      url = {https://eprint.iacr.org/2018/116}
}