Cryptology ePrint Archive: Report 2018/330

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

Joseph K. Liu and Tsz Hon Yuen and 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).

Category / Keywords: public-key cryptography / Revocable Attribute-Based Encryption

Original Publication (with major differences): ACNS 2018

Date: received 9 Apr 2018

Contact author: joseph liu at monash edu

Available format(s): PDF | BibTeX Citation

Version: 20180410:020234 (All versions of this report)

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