Method and device for the protected storage of data from message traffic

Method and processor (12) for:a. setting up a telecommunication link between various communication appliances (1, 2, 3, 7, 8, 9);b. setting up a monitoring link (13) between the telecommunication link and the processor (12);c. the storage in enciphered form of a first identity of either a first user of a first communication appliance (1, 2, 3) or of the first communication appliance (1, 2, 3) and a second identity of either a second user of a second communication appliance (7, 8, 9) or of the second communication appliance (7, 8, 9);d. the storage of the data despatched via the telecommunication link, which data have been enciphered prior to the storage using a symmetrical conversation key;e. the storage of the conversation key enciphered using public keys of the users;f. the signing of the data stored using the symmetrical conversation key and also of the first and second identities stored in enciphered form.