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Security and Communication Networks
Volume 2017, Article ID 1404279, 16 pages
https://doi.org/10.1155/2017/1404279
Research Article

Adaptive Security of Broadcast Encryption, Revisited

Key Laboratory of Cryptologic Technology and Information Security, Ministry of Education, Shandong University, Jinan, China

Correspondence should be addressed to Puwen Wei; nc.ude.uds@iewp and Mingqiang Wang; nc.ude.uds@gnaiqgnimgnaw

Received 21 February 2017; Accepted 27 April 2017; Published 3 July 2017

Academic Editor: Paolo D’Arco

Copyright © 2017 Bingxin Zhu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We provide a strong security notion for broadcast encryption, called adaptive security in the multichallenge setting (MA-security), where the adversary can adaptively have access to the key generation oracle and the encryption oracle many times (multichallenge). The adversary specially can query for the challenge ciphertexts on different target user sets adaptively, which generalizes the attacks against broadcast encryptions in the real world setting. Our general result shows that the reduction of the adaptive secure broadcast encryption will lose a factor of in the MA setting, where is the maximum number of encryption queries. In order to construct tighter MA-secure broadcast encryptions, we investigate Gentry and Water’s transformation and show that their transformation can preserve MA-security at the price of reduction loss on the advantage of the underlying symmetric key encryption. Furthermore, we remove the -type assumption in Gentry and Water’s semistatically secure broadcast encryption by using Hofheinz-Koch-Striecks techniques. The resulting scheme instantiated in a composite order group is MA-secure with constant-size ciphertext header.