Secure multimedia data transmission method

1. A secure method of digital data transmission between a sender and a receiver, including the following phases:

receiver authentication by a symmetrical authentication key sharing algorithm with no transmission of the key;

data watermarking by using the authentication key as the watermarking key; and

transmission of the watermarked data,

wherein the authentication phase includes the steps of:

transmission, from the sender to the receiver, at least of a random number and of an identifier of the sender;

calculation of the authentication key by the receiver based at least on the sender identifier and on a secret quantity of the receiver;

transmission, from the receiver to the sender, at least of an identifier of the receiver and of a first quantity representing said random number, encrypted with the authentication key calculated by the receiver; and

calculation of the authentication key by the sender based at least on the identifier of the receiver and on a secret quantity of the sender,

wherein the step of authentication key calculation by the sender is followed by the steps of:

calculation of a second quantity representing said random number, encrypted with the authentication key calculated by the sender; and

identity checking between the first and second encrypted quantities.

2. The method of claim 1 , wherein the watermarking phase includes inserting a message in the data.

3. The method of claim 2 , wherein the watermarking phase includes the steps of:

drawing, at the receiver, a random number and transmission of this number to the sender; and

watermarking the data by the sender by using said random number as a message to be inserted and the authentication key as the watermarking key.

4. The method of claim 3 , including, in receive mode, the steps of:

decoding of the data by using the authentication key to extract a message; and

identity checking between the extracted message and said random number.

5. The method of claim 2 , wherein the watermarking phase includes the step of data watermarking by the sender by using the authentication key and any quantity as a message to be inserted.

6. The method of claim 5 , wherein in receive mode, the receiver decodes the data by using the authentication key, the obtaining or not of a message after this decoding meaning an authentic transmission or not.

7. The method of claim 1 , wherein the digital data are multimedia data.