A method is presented for distributing cryptographic keys in a hierarchized network including at least one device in charge of a higher group of devices, wherein at least one of the devices of the higher group of devices is also in charge of a lower group of devices. The method includes the steps of: a) storing a set of identifiers particular to the higher group, an identifier particular to the device in charge, an identifier per device in charge of a lower group, each identifier being unique; storing a root cryptographic key; c) providing a root cryptographic key to each device in charge of a lower group using a first non-reversible cryptographic function; d) providing at least one transport cryptographic key to each member of said higher group of devices using a second non-reversible cryptographic function.