Abstract: A method is disclosed for conditional access to a digital data stream encrypted with at least one first control word and broadcasted via an emitter of a broadcasting network to at least one mobile equipment. The latter also is connected via a mobile communication network to a management center. The stream contains control messages encrypted with a transmission key and includes a second control word obtained by the encryption of the first control word with a local key. The method includes reception by the mobile equipment of at least one cryptogram via the mobile network, determination of at least one local key from the received cryptogram, and reception of a control message via the broadcasting network, decryption of the message and obtaining the second control word.