Security analysis of authenticated key exchange protocol based on the q-th root problem

Abstract

Johnston and Gemmell proposed an authenticated key exchange protocol based on the difficulty of the q-th root problem. They showed that it is provably secure against man-in-the-middle attacks. In this paper we show that the protocol is insecure against an unknown key-share attack and does not achieve forward secrecy. © 2007 The Institute of Electronics, Information and Communication Engineers.