| 摘要 |
A method and apparatus for encryption of data between a first device 12 and a second device 30, in which one or more precalculated key pairs 41 are stored in a memory of the first device 12, the or each key pair comprising a session key and an encrypted version of the session key. The encrypted version is passed to the second device 30, which decrypts 42 the session key, this session key being thereafter used to encrypt data communicated from the second device 30 to the first device 12 and/or vice versa. The invention is particularly applicable to a digital television system in which data, notably control word data, is to be communicated in encrypted form between a decoder and an associated portable security module. <IMAGE> |
