| 摘要 |
The invention relates to a method of establishing a session key (KS) between a unit for descrambling scrambled multimedia signals and a removable cryptographic unit. According to the invention, one of the units sends (166, 184) the other unit a message containing a received random number, a term (a) and a signature for the random number and/or the term (a), which is produced with a private key (K3pr) and, subsequently, the other unit checks (168, 192) the signature using a public key (K3pu) corresponding to the private key (K3pr) and compares (174, 198) the received random number with that sent. If the signature is incorrect or if the received random number does not correspond to that sent, the subsequent steps for establishing the session key are not performed. |
