The aim of this study is to make sure that the requested confidential digital object is authenticated and hence no tampering can be performed upon it particularly at the client-side. Thus a novel web client authentication system using smart card has been developed, called Dynamic HMAC Validation System (DHVS). The DHVS is based on HMAC technology where the ciphering key is dynamically generated every time the client sends a request. This solution is implemented as a prototype. Such prototype consists of two parts: the DHVS at the client-side, and DHVS at the server-side. The evaluation results show that the DHVS provides a higher level of client authentication for different kinds of e-systems and indeed this is an ultimate security requirement.