A robust ElGamal-based password-authentication protocol using smart card for client-server communication

Smart card-based client-server authentication protocol is well popular for secure data exchange over insecure and hostile networks. Recently, Lee et al. put forward an authentication protocol by utilizing ElGamal cryptosystem and proved that it can withstand known security threats. This article evinces that the protocol of Lee et al. is unwilling to protect various important security vulnerabilities such as forgery attack and off-line password-guessing attack. To vanquish these loopholes, this article presents a robust authentication protocol for client-server communication over any insecure networks. The security explanation of our protocol has done through the formal and informal mechanism and its outcome makes sure that the designed protocol is strong enough to resist the known vulnerabilities. In addition, we have simulated our protocol using ProVerif online software and its results certify that our protocol is safe against private information of the client and server. This paper also has made performance estimation of the presented protocol and others, and the outcome favors the presented protocol.