Security Analysis of Joint Group Key Agreement Protocol

Chik-How TAN  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.9   pp.1876-1878
Publication Date: 2007/09/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.9.1876
Print ISSN: 0916-8508
Type of Manuscript: Special Section LETTER (Special Section on Information Theory and Its Applications)
group key agreement,  backward secrecy,  

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In a secure group communication, a group key agreement is to provide a secret key exchange among a group of users. When a new user joins the group, a new group key will be established. In this paper, we analyse Horng's joint protocol and show that this protocol does not provide backward secrecy. This means that a new joining user is able to discover the previous group key used by the previous group member.