System and method for authenticating an electronically transmitted document
Crytographic key notarization methods and apparatus
Method and apparatus providing registered mail features in an electronic communication system
Method and apparatus for computing and implementing error detection check bytes
Solid state key for controlling access to computer systems and to computer software and/or for secure communications
Reliable document authentication system
Method and apparatus for synchronizing generation of separate, free running, time dependent equipment
Identification authenticating system
ApplicationNo. 509447 filed on 04/16/1990
US Classes:713/178, Time stamp340/5.81, Personal identification380/51Having production of printed copy (e.g., printer, typewriter)
ExaminersPrimary: Buczinski, Stephen C.
Attorney, Agent or Firm
International ClassesH04K 001/00
AbstractMethod and apparatus for determining that a first unit of data associated with a first party has not been modified since a specified point in time. A method includes the steps of (a) providing the first unit of data and (b) generating a second unit of data from the first unit of data, the second unit of data being expressive of an information content of the first unit of data. The method further includes a step of (c) generating a time indication for specifying a point in time, the time indication being generated with time generation means having a time is settable by a second party other than the first party. That is, the time generation means is secured and cannot be altered or changed by the first party. The method further includes a step of (d) encrypting the second unit of data and the generated time indication to generate a third unit of data. The method includes as an additional step a step of (e) validating the first unit of data to ensure that the first unit of data has not been modified since the specified point in time.