One of crucial disadvantages of key predistribution schemes for ad hoc networks is that if devices A and B use a shared key K to determine their session keys, then any adversarial device that holds K can impersonate A against B (or vice versa). Also, the adversary can eavesdrop communication between A and B for the lifetime of the system.#R##N##R##N#We develop a dynamic scheme where a system provider periodically broadcasts random temporal keys (e.g. via a GSM network) encrypted with keys from the main predistribution pool. Shared temporal keys (and not the keys from the main pool) are used to establish session keys. The trick is that the scheme broadcast is organized in such a way that with a high probability two devices share much more temporal keys than the keys from the main pool of keys. It is a kind of paradox, but this makes it possible not only to protect communication against an adversary that has collected a large fraction of keys from the main pool, but also makes the system well suited for authentication purposes.
['Jacek Cichoń', 'Zbigniew Gołębiewski', 'Mirosław Kutyłowski']
From key predistribution to key redistribution