| 摘要 |
PURPOSE: Process for managing a symmetric key in a communication network and devices for the implementation of the process are provided, which relates to a process of symmetric key management in a communication network comprising a device of a first type furnished with a source of data to be broadcast over the network and at least one device of a second type intended to receive thee data. CONSTITUTION: The source device creates and then stores the "short-term" symmetric key Kc(step 4.2), which key serves to encrypt the control words CW. This symmetric key is, according to the present exemplary embodiment, chosen randomly and preferably possesses a length of 128 bits. The key Kc is encrypted with the aid of the public key PUB2 by way of an asymmetric encryption algorithm E1, then transmitted in encrypted form E1{PUB2}(Kc) to the receiver device(step 4.4). The latter decrypts the key Kc with the aid of its private key PRIV2, encrypts it again according to a symmetric encryption algorithm E2 with the aid of the symmetric network key Kn(step 4.5) and sends Kc thus encrypted(i.e. E2{Kn}(Kc)) back to the source device(step 4.6), which stores the information item(step 4.7).
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