1. A method to protect stored data, 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; and allowing the device to access the stored data based on the authorization status at the time the request is received.