function hash_password(form, element_name, challenge_string) {
    var password_box = form.elements[element_name];
    var password     = password_box.value;

    password_box.value = calcMD5(challenge_string + ":" + password);
}

function display_password_box(name, value, class_name) {
    document.write('<input type="password" name="' + name + '" value="' + value + '"');
    if (class_name.length) {
        document.write(' class="' + class_name + '"');
    }
    document.write('>');
}