Controlled dissemination of digital information
 The present invention is a method and apparatus for controlling the dissemination of digital information. Digital information is structured logically to incorporate usage history and allowable access window before it is encrypted in a header portion and a body portion. The end user accesses the digital information with a tamper-proof controlled information access device by decrypting the digital information. A controller disposed in the controlled information access device permits end users to access transparently uncontrolled information. Controlled digital information will be accessed as long as the conditions specified by the information provider are met. In one embodiment of the present invention, controlled information is disseminated in an off-line manner while the second embodiment of the present invention disseminates controlled digital information in an on-line manner. 
National University of Singapore
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H04N G07F G06F G06F
inventional inventional additional inventional
Weiguo Arcot D. Mohan S.
Wang Narasimhalu Kankanhalli