a printing medium has means for storing electronic data . the means includes an input - output unit , a first memory , a second memory , a comparison unit , and an access controller . the second memory stores data for confirming the validity of the information printed on the printing medium . the first memory stores data for controlling access to the second memory . in particular , write access to the second memory is denied unless the accessing party also submits comparison data that compare correctly with the data stored in the first memory . this protocol prevents the facile creation of counterfeit copies .