A method of storage of digital data on a physical medium equipped with calculation circuitry, by ciphering the data using a symmetrical algorithm with a ciphering key independent from the recorder, and by transferring the ciphering key onto the medium or its calculation by an asymmetrical algorithm and a read method in which, on first reading from the physical medium, a user key is transferred to the calculation circuitry by an asymmetrical ciphering process, a ciphered key of the data ciphering key is calculated in the calculation circuitry of the medium and by a symmetrical algorithm with the user key, and the asymmetrical ciphering portion of the calculation circuitry are deactivated.