A method of authenticating a device's access to a communications node is disclosed. The method of operation includes the communications node generating a first value for use in the derivation of a first encryption key, the first encryption key being at least partially used to authenticate the device's access to the communications node in a first communications exchange. The method of operation includes the communications node modifying the first value, independent of the device, to create a second value. The method includes the communications node using the second value in authenticating the device's access to the communications node in a second communications exchange. Embodiments of the present invention include but are not limited to communications nodes and devices, subsystems, and systems equipped to operate in the above-described manner.