Patent ID: 8006102

Claim:
A data transmission device, comprising: a storage unit for storing encrypted data; an authentication unit for authenticating a device that is to be a destination of transmission; a selection unit for selectively supplying the encrypted data read out from the storage unit, the selection unit being controlled by an authentication result received from the authentication unit; a re-encryption unit for decoding the encrypted data supplied from the selection unit and for re-encrypting the decoded data; and an output unit to which one of the encrypted data from the selection unit and the re-encrypted data from the re-encryption unit is supplied; the selection unit supplying the encrypted data read out from the storage unit to the re-encryption unit when the device that is to be the destination of transmission has been authenticated by the authentication unit so that the output unit is supplied with the re-encrypted data from the re-encryption unit, and supplying the encrypted data read out from the storage unit directly to the output unit when the device that is to be the destination of transmission has not been authenticated by the authentication unit.