Patent ID: 8005118
Filing Date: 2011-08-23
Classification: G06F

Abstract:
1. A slave device having no internal power source, the slave device accessing a host device having an internal power source and transmitting and receiving data, the slave device comprising: a clock control unit which performs control such that time information of the host device is acquired and a counter value corresponding to the acquired time information is set, if the clock control unit is connected to the host device and is supplied with power from the host device; a counter which changes the set counter value in steps of a predetermined value at regular time intervals while the power is supplied; a time information unit which updates current time information to correspond to the counter value changed by the counter while the power is supplied; a rights object storage unit which stores a rights object for a content object; and a rights object update acknowledgement unit which generates an acknowledgement and transmits the generated acknowledgement to the host device, when there is a request for an update of the rights object from the host device, wherein the acknowledgement is based on the time information stored in the time information unit, and wherein the host supplies power to the clock control unit and the time information unit.