A method of securing an industrial control system includes operating the industrial control system in an open mode, wherein communications between a plurality of devices of the industrial control system are unencrypted when the industrial control system is in the open mode. The method includes exchanging security tokens between the plurality of devices of the industrial control system. The method further includes ceasing operating the industrial control system in the open mode and instead operating the industrial control system in a secure mode, wherein the communications between the plurality of devices of the industrial control system are encrypted using the security tokens when the industrial control system is operating in the secure mode.