A Mutual Authentication Scheme Based On Elgamal Digital Signature Algorithm

With the continuous development of the network technology and the rapid popularization of Internet, Internet is faced with various security threats. How to effectively protect crucial data transmitted on the network and how to improve the security of Internet have become an important problem needed to be solved completely. For these reasons, the thesis aims to study in depth the relevant problems about the ElGamal digital signature algorithm and mutual identity authentication technique.In the respect of the ElGamal digital signature algorithm, since ElGamal digital signature algorithm can not resist the identical signature key attack and the isomorphic attack, the author makes use of the idea based on double privacy keys to improve ElGamal digital signature algorithm. Thus, the above two types of attacks can be avoided in the improved ElGamal algorithm.In the respect of the research related on the mutual identity authentication, a mutual identity authentication based on Harn signature algorithm is studied in this thesis, which can thwart the replay attack and the man-in-the-middle attack. But since Harn digital signature algorithm is not secure, it leads some flaws exist in the mutual identity authentication protocol based on it. Therefore, the thesis replaces Harn digital signature algorithm with improved ElGamal digital signature algorithm, and a new mutual identity authentication protocol based on improved ElGamal algorithm is obtained. The new mutual identity authentication protocol not only can resist the replay attack and the man-in-the-middle attack, but also eliminates the flaws existed in the original one. Finally, after strict formal analysis with BAN logic, it is proved that the new mutual identity authentication protocol is secure.