Patent ID: 8061793

Claim:
A mobile device for printing onto a print medium in a print direction, the print medium including first coded data that encodes a unique print medium identity and a digital signature associated with the unique print medium identity, the first coded data having a linear extent, the mobile device comprising: a media feed path extending through the mobile device; drive means for driving the print medium in a media feed direction along the print path; a sensor in the media feed path for sensing the first coded data while the print medium moves past the sensor; processor for decoding the first coded data and extracting the unique print medium identity and the digital signature; a transmitter configured to transmit a first message from the processor to a remote computer system, the first message being indicative of the unique print medium identity and the digital signature; a receiver for receiving a second message from the remote computer system in reply to the first message, the second message being indicative to the processor of an authenticity of the print medium; and a printhead for printing onto the print medium under control of the processor in the event the print medium is authentic, the printhead being separated from the sensor in the media feed direction by a distance smaller than the linear extend of the first coded data.