PROCESS FOR MANAGING A SYMMETRIC KEY IN A COMMUNICATION NETWORK AND DEVICES FOR THE IMPLEMENTATION OF THIS PROCESS

摘要

Process for managing a symmetric key in a communication network and devices for the implementation of this process The communication network comprises a device of a first type (1) furnished with a source of data to be broadcast over the network and at leas t one device of a second type (2) intended to receive the said data. The symmetric key management process comprises the following steps: - the source device (1) determines a first symmetric key (Kc) and transmits it securely (E1{PUB2}(Kc)) to at least one receiver device (2); - a receiver device (2) receives the first symmetric key (Kc), encrypts it (E2) with the aid of a second symmetric key (Kn), known to the receiver devices (2) of the network and transmits it to the source device; - the source device (1) recovers the encryption (E2{Kn}(Kc)) of the first symmetric key (Kc) and stores it. Before transmitting the data (CW) to at least one reception device (2), the source device (1) encrypts (E3) these data with the aid of the firs t symmetric key (Kc), then it transmits these encrypted data (E3{Kc}(CW)), accompanied by the first encrypted symmetric key (E2{Kn}(Kc)), to at least o ne receiver device (2). The receiver device (2) decrypts the first symmetric key (Kc) with the aid of the second key (Kn) which it possesses, then it decrypts the encrypte d data with the aid of the first symmetric key thus recovered. The invention also pertains to devices for implementing the process.