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SHU-HUI CHANG1, CHUAN-MING LI2 AND TZONELIH HWANG3
1Center of General Education
Southern Taiwan University of Technology
Tainan, 710 Taiwan
2Department of Information Management
Shu-Zen College of Medicine and Management
Kaohsiung, 821 Taiwan
3Department of Computer Science and Information Engineering
National Cheng Kung University
Tainan, 701 Taiwan
This paper presents an identity-based hierarchical designated decryption (IHDD)
scheme which allows a message sender to generate ciphertexts that can be decrypted by
(1) only a specified recipient or (2) a specified recipient and all or some of its ancestor
users in the hierarchy tree. The newly proposed scheme can be considered as a combination
of the hierarchical identity-based encryption (HIBE) and the identity-based
multi-recipient encryption scheme (ID-based MRES). However, the purpose and structure
of the proposed IHDD scheme are different from those of the HIBE and the ID-based
MRES. The proposed IHDD scheme has low computation complexity, in which the decryption
operation needs only one bilinear pairing computation, and constant length private
keys wherein the length of users¡¦ private keys is independent of the hierarchy depth.
The security of the proposed scheme is based on the decision bilinear Diffie-Hellman
inversion assumption without using random oracles.
Received June 20, 2008; revised December 2, 2008 & March 9, 2009; accepted August 13, 2009.
Communicated by Wen-Guey Tzeng.
* This research was supported by the National Science Council of Taiwan, R.O.C., under the Contract No.
NSC 95-2221-E-006-071.