Patent ID: 8509447

Claim:
A method for distribution of cryptographic keys in a hierarchized network comprising at least one device responsible for a first group of devices as a higher group, one or more devices of the first group of devices also being responsible for a second group of devices lower than the first group of devices, the method comprising the steps, at the at least one device responsible for the higher group, of: a. storing a set of identifiers specific to the first group of devices, an identifier specific to the responsible device of the first group of devices, an identifier for each device responsible for the second group of devices, each identifier being unique inside the hierarchized network, b. storing a root cryptographic key, c. supplying the root cryptographic key to the each device responsible for the second group of devices by derivation from the root cryptographic key and from the identifier for each device responsible for the second group of devices by a first, nonreversible cryptographic function, and d. supplying one or more transport cryptographic keys to each member of the first group of devices by derivation from the root cryptographic key and from an identifier belonging to the set of identifiers specific to the first group of devices by a second, nonreversible cryptographic function.