### Time-Based Direct Revocable Ciphertext-Policy Attribute-Based Encryption with Short Revocation List

Joseph K. Liu, Tsz Hon Yuen, Peng Zhang, and Kaitai Liang

##### Abstract

In this paper, we propose an efficient revocable Ciphertext-Policy Attribute-Based Encryption (CP-ABE) scheme. We base on the direct revocation approach, by embedding the revocation list into ciphertext. However, since the revocation list will grow longer as time goes by, we further leverage this by proposing a secret key time validation technique so that users will have their keys expired on a date and the revocation list only needs to include those user keys revoked before their intended expired date (e.g. those user keys which have been stolen before expiry). These keys can be removed from the revocation list after their expiry date in order to keep the revocation list short, as these keys can no longer be used to decrypt ciphertext generated after their expiry time. This technique is derived from Hierarchical Identity-based Encryption (HIBE) mechanism and thus time periods are in hierarchical structure: year, month, day. Users with validity of the whole year can decrypt any ciphertext associated with time period of any month or any day within the year. By using this technique, the size of public parameters and user secret key can be greatly reduced. A bonus advantage of this technique is the support of discontinuity of user validity (e.g. taking no-paid leave).

Available format(s)
Category
Public-key cryptography
Publication info
Published elsewhere. MAJOR revision.ACNS 2018
Keywords
Revocable Attribute-Based Encryption
Contact author(s)
joseph liu @ monash edu
History
Short URL
https://ia.cr/2018/330

CC BY

BibTeX

@misc{cryptoeprint:2018/330,
author = {Joseph K.  Liu and Tsz Hon Yuen and Peng Zhang and Kaitai Liang},
title = {Time-Based Direct Revocable Ciphertext-Policy Attribute-Based Encryption  with  Short Revocation List},
howpublished = {Cryptology ePrint Archive, Paper 2018/330},
year = {2018},
note = {\url{https://eprint.iacr.org/2018/330}},
url = {https://eprint.iacr.org/2018/330}
}

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