A method of using a mobile device to authenticate a print medium offline before completing printing onto the print medium, the mobile device including processing means, a printhead and a sensor, the print medium comprising a laminar substrate, the method comprising the steps of: using the sensor to sense...http://www.google.ca/patents/US8020002?utm_source=gb-gplus-sharePatent US8020002 - Method of authenticating print medium using printing mobile device
