Paper 2016/693

Identity-Based Key Aggregate Cryptosystem from Multilinear Maps

Sikhar Patranabis and Debdeep Mukhopadhyay

Abstract

The key-aggregate cryptosystem~(KAC) proposed by Chu et al. in 2014 offers a solution to the flexible access delegation problem in shared data environments such as the cloud. KAC allows a data owner, owning $N$ classes of encrypted data, to securely grant access to any subset $S$ of these data classes among a subset $\hat{S}$ of data users, via a single low overhead \emph{aggregate key} $K_{\mathcal{S}}$. Existing constructions for KAC are efficient in so far they achieve constant size ciphertexts and aggregate keys. But they resort to a public parameter that has size linear in the number of data classes $N$, and require $O(M'M)$ secure channels for distribution of aggregate keys in a system with $M'$ data owners and $M$ data users. In this paper, we propose three different multilinear-map based KAC constructions that have at most polylogarithmic overhead for both ciphertexts and public parameters, and generate constant size aggregate keys. We further demonstrate how the aggregate keys may be efficiently broadcast among any arbitrary size subset of $M$ data users using only $O(M'+M)$ secure channels, in a system with $M'$ data owners. Our constructions are secure in the generic multilinear group model and are fully collusion resistant against any number of colluding parties. In addition, they naturally give rise to \emph{identity based} secure access delegation schemes.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint. MINOR revision.
Keywords
Key-Aggregate CryptosystemIdentity-basedOnline Data SharingMultilinear MapsCollusion-resistant
Contact author(s)
sikharpatranabis @ gmail com
History
2016-07-13: received
Short URL
https://ia.cr/2016/693
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2016/693,
      author = {Sikhar Patranabis and Debdeep Mukhopadhyay},
      title = {Identity-Based Key Aggregate Cryptosystem from Multilinear Maps},
      howpublished = {Cryptology ePrint Archive, Paper 2016/693},
      year = {2016},
      note = {\url{https://eprint.iacr.org/2016/693}},
      url = {https://eprint.iacr.org/2016/693}
}
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