Patent ID: 7380118

Claim:
A data transmitting apparatus for transmitting data to a data receiving apparatus via a communication interface using an asynchronous communication method, the data transmitting apparatus comprising: a connection establishment unit operable to establish a logical transmission path between said data transmitting apparatus and the data receiving apparatus by exchanging information with the data receiving apparatus; a device authentication unit operable to perform a device authentication for the data receiving apparatus (i) before the logical transmission path is established, (ii) during a process of establishing the logical transmission path, or (iii) after the logical transmission path is established; an encryption key sharing unit operable to generate an encryption key based on a result of the device authentication performed by said device authentication unit and allow shared use of the generated encryption key between said data transmitting apparatus and the data receiving apparatus by communicating, using a reserve field in a dedicated area for notifying a status of the transmission, information pertaining to a changing timing of the encryption key; and a data transmission unit operable to encrypt the data using the shared encryption key and transmit the encrypted data to the data receiving apparatus.