BigPatents India

A cancellation server for canceling cryptographic puzzles, the puzzles associated with identifiers, for use in a digital delivery system comprising an intended recipient of a digital object including a cryptographic puzzle, the cancellation server in connection with at least one database, and executing the steps of: receiving the identifier associated with the recipient"s puzzle; querying the at least one database with the identifier; and canceling the intended recipient"s puzzle if query fails, by causing an entry to be stored stored in the at least one database, wherein the entry comprises the identifier or information derived from the identifier.