Abstract: Method for checking the signature of a message. The message, signature, and a certificate are sent by a signer having a public key to a recipient having a message storage device. The certificate is checked by a protected device connected to the message storage device and a checking result data element is sent for checking to a display device connected to the protected device. When the certificate is verified, a reduction of the message is calculated in the protected device and the message is recopied onto the display device. The signature is decrypted using the public key in the protected device, and the decrypted signature is compared with the reduction carried out. According to the comparison, a message is sent from the protected device to the display device indicating whether the signature conforms or does not conform to the message or to the public key of the signer put forward.

Abstract: The invention concerns a protected optical disk for storing data. It also concerns a method for protecting said disk. The invention is characterized in that said disk firstly comprises a portable object comprising a memory including at least one secret key, and secondly data exchange means, said key making it possible to decrypt the data of said disk whilst remaining in said portable object, said exchange means making it possible to exchange said data between said portable object and said disk. The invention can be applied in particular to CD-ROMs.

Abstract: Method for checking the signature of a message, the message, signature, and a certificate having been sent by a signer having a public key to a recipient having a message storage device.

Abstract: Method for checking the signature of a message, the message, signature and a certificate having,been sent by a signer having a public key to a recipient having a message storage device (11).

Abstract: The invention relates to a method and a system for transmitting messages between a control terminal and controlled terminals for use especially in home automation installations. The controlled terminals are installed on a transmission network connected to the control terminal. The messages all have the same structure and include an originator field and a destination field. To install a new terminal a data item specific thereto is entered in the terminal. The new terminal installed transmits an installation request message including the specific data item to the terminal. In response the control terminal transmits an installation message which includes all the data needed for the installed terminal to converse with the control terminal.