The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 08, 1993
Filed:
Dec. 05, 1991
Hitachi Ltd., Tokyo, JP;
Hitachi Chubu Software, Ltd., Aichi, JP;
Abstract
A method and apparatus for carrying out limited encipherment broadcast by generating a cipher key obtained from destination information added to service information are provided. An information service station transmits to each receiving station a random number, destination information for designating a destination station, and enciphered data obtained by enciphering service information by a common key generating by using the random number and destination information. An IC card at each receiving station which is provided in advance with a key generating function from the information service station, generates the common key by using the received random number and destination information only when it is confirmed from the destination information that the receiving station has a data reception right, and deciphers the enciphered data by using the common key to obtain the original service information. The processing time required for generating the common key can be reduced because of a small amount of data to be used.