Patent attributes
An administration entity controls access to an electronic device by generating credentials and a plurality of corresponding proofs, wherein no valid proofs are determinable given only the credentials and values for expired proofs. The electronic device receives the credentials and, if access is authorized at a particular time, the electronic device receives a proof corresponding to the particular time and confirms the proof using the credentials. A single administration entity may generate the credentials and generate the proofs and/or there may be a first administration entity that generates the credentials and other administration entities that generate proofs. The credentials may be a digital certificate that includes a final value that is a result of applying a one way function to a first one of the proofs.
