Communication system for portable appliances

摘要

A portable device 12 is capable of communicating with a host device 10 remotely, via a communications network 22 which may be prone to interception, and directly (e.g. via an I.R. Link 24, 40), when the devices are in close physical proximity and when the risk of interception is minimal. The host device 10 and the portable device 12 update a shared security key or the like when they communicate directly and this key is used to authenticate the portable device 12 and/or encrypt the communication when the portable device 12 attempts to communicate remotely.