ID-Based Authenticated Group Key Agreement Secure against Insider Attacks

Kyu Young CHOI  Jung Yeon HWANG  Dong Hoon LEE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.7   pp.1828-1830
Publication Date: 2008/07/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.7.1828
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Cryptography and Information Security
authenticated group key agreement,  ID-based cryptography,  insider attack,  

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In 2004, Choi et al. proposed an ID-based authenticated group key agreement. Unfortunately, their protocol was found to be vulnerable to the insider attacks by Zhang, Chen and Shim. To prevent insider attacks, Shim presented a modification of Choi et al.'s protocol. In this letter, we first show that Shim's modification is still insecure against insider attacks. We then present a modification of Choi et al.'s protocol that resists insider attacks. The counter-measure uses an ID-based signature on transcripts in order to bind them in a session. This prevents any replay of transcripts. Especially, by applying ID-based batch verification, the proposed one still consists of two rounds and is computationally efficient.