A method to protect stored data is provided, comprising performing one or more times, by a processor, the following actions: receiving from a device verification information generated using common information known to the device and to the processor, verifying the validity of the verification information using the common information, determining an authorization status of the device based on (1) the validity of the verification information and (2) the time the verification information is received by the processor, and receiving a request from the device to access the stored data. The device is allowed to access the stored data based on the authorization status at the time the request is received.