A method and apparatus for updating an encryption key for performing encrypted communication over a communications network. The method comprises, within a timestamp distribution node, transmitting a message to at least one timestamp reception node of the communications network containing a timestamp value. The method further comprises, within the at least one timestamp reception node, receiving the message from the timestamp distribution node and extracting the timestamp value. Wherein, within each of the timestamp distribution node and the at least one timestamp reception node, the method comprises generating at least one updated encryption key for performing encrypted communication based at least partly on the extracted timestamp value.