Abstract: A method and system is disclosed for purposefully modifying the accessibility of information encoded upon an optical medium for indicating a state or history of the optical medium and/or a state or history of an item associated therewith. In one embodiment, the optical medium is purposefully damaged when the information is initially accessed so that upon subsequent access attempts of the information on the optical medium, a previous access of the information is detected by the purposefully induced errors. Thus, there is provided an effective technique for limiting illegal duplication and/or use of, e.g., software, movies, and music on compact disks and digital versatile disks. The present invention provides verification of persons and/or financial transaction cards during financial transactions. In another embodiment, a compact data storage device is disclosed having the approximate dimensions of a credit card that is capable of storing large amounts of data (e.g., 50-100 Megabytes).