function trylogin() {
    var loginForm = document.getElementById("loginForm");
    if (loginForm.username.value == "") {
         alert("Please enter your user name.");
         return false;
    }
    if (loginForm.password.value == "") {
        alert("Please enter your password.");
        return false;
    }
    var submitform = document.getElementById("submitform");
    submitform.username.value = loginForm.username.value;
    submitform.response.value =
    	hex_md5(loginForm.challenge.value+loginForm.password.value);
    submitform.submit();
}