### Unbounded Dynamic Predicate Compositions in ABE from Standard Assumptions

Nuttapong Attrapadung and Junichi Tomida

##### Abstract

At Eurocrypt'19, Attrapadung presented several transformations that dynamically compose a set of attribute-based encryption (ABE) schemes for simpler predicates into a new ABE scheme for more expressive predicates. Due to the powerful unbounded and modular nature of his compositions, many new ABE schemes can be obtained in a systematic manner. However, his approach heavily relies on $q$-type assumptions, which are not standard. Devising such powerful compositions from standard assumptions was left as an important open problem. In this paper, we present a new framework for constructing ABE schemes that allow unbounded and dynamic predicate compositions among them, and show that the adaptive security of these composed ABE will be preserved by relying only on the standard matrix Diffie-Hellman (MDDH) assumption. This thus resolves the open problem posed by Attrapadung. As for applications, we obtain various ABEs that are the first such instantiations of their kinds from standard assumptions.These include the following adaptively secure large-universe ABEs for Boolean formulae under MDDH: - The first completely unbounded monotone key-policy (KP)/ciphertext-policy (CP) ABE. Such ABE was recently proposed, but only for the KP and small-universe flavor (Kowalczyk and Wee, Eurocrypt'19). - The first completely unbounded non-monotone KP/CP-ABE. Especially, our ABEs support a new type of non-monotonicity that subsumes previous two types of non-monotonicity, namely, by Ostrovsky et al. (CCS'07) and by Okamoto and Takashima (CRYPTO'10). - The first (non-monotone) KP and CP-ABE with constant-size ciphertexts and secret keys, respectively. - The first KP and CP-ABE with constant-size secret keys and ciphertexts, respectively. At the core of our framework lies a new partially symmetric design of the core 1-key 1-ciphertext oracle component called Key Encoding Indistinguishability, which exploits the symmetry so as to obtain compositions.

Available format(s)
Category
Public-key cryptography
Publication info
A major revision of an IACR publication in ASIACRYPT 2020
Keywords
Attribute-based encryptionpredicate compositionsstandard assumptionscompletely unbounded ABEnon-monotone ABEsuccinct ABE
Contact author(s)
n attrapadung @ aist go jp
junichi tomida vw @ hco ntt co jp
History
2020-09-18: last of 2 revisions
See all versions
Short URL
https://ia.cr/2020/231

CC BY

BibTeX

@misc{cryptoeprint:2020/231,
author = {Nuttapong Attrapadung and Junichi Tomida},
title = {Unbounded Dynamic Predicate Compositions in ABE from Standard Assumptions},
howpublished = {Cryptology ePrint Archive, Paper 2020/231},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/231}},
url = {https://eprint.iacr.org/2020/231}
}

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