Patent ID: 7278018

Claim:
A network including: a pen having an optical image sensor for sensing coded data printed on a surface, said coded data identifying a page identity for the surface and a plurality of locations on the surface; a base station for communication with the pen; and a registration server, the network characterized by: a secret key and a public unique identifier being installed in a non-volatile memory of the pen and in a database of the registration server, before the pen is connected to the network; the registration server configured to authenticate the pen when the pen is connected to the network by verifying an encryption from the pen, using the secret key, of a challenge message; upon successful authentication, the pen being registered in the database of the registration server; and the pen, when placed in an operative position relative to the surface, configured to capture images of the coded data, process the captured images and transmit to the base station digital ink comprising a series of strokes, each stroke comprising a sequence of time-stamped positions of the pen and the page identity.