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The Boston Community Information System (also called BCIS or Boston COMINS) transmitted up-to-the-minute ''Associated Press'' and ''New York Times'' wire reports to subscribers in Boston from April 1984 to January 1988.〔 The Boston Community Information System was the first system to propose and implement "hybrid broadcasting", combining both push technology and pull technology.〔 Marvin Zelkowitz. ("Advances in Computers: Web Technology, Volume 67" ). 2006. p. 15. 〕 The Boston Community Information System (BCIS) used a FM radio channel to broadcast news to people who decoded the information with radio receivers connected to personal computers.〔 George Samaras. ("Chapter 4 - Data Dissemination by Broadcast" ) 〕〔 Tak W. Yan and Hector Garcia-Molina. ("The SIFT Information Dissemination System" ). http://ilpubs.stanford.edu:8090/433/1/2000-12.pdf p. 3. 〕 The BCIS system was designed and implemented by David K. Gifford and his research group at MIT. In order to deny service to nonpaying customers, and in order to allow each customer to subscribe to any subset of information streams, Gifford developed a conditional access system that used a different randomly chosen ephemeral key to encrypt each news article, before broadcasting the encrypted article on a subcarrier of MIT's FM radio station WMBR. Unlike many other broadcast encryption systems, Gifford's cipher was unbroken for almost a decade, during the entire operation of the BCIS.〔 Thomas R. Cain and Alan T. Sherman. ("How to break Gifford's cipher" ). Cryptologia. 1997. 〕 == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Boston Community Information System」の詳細全文を読む スポンサード リンク
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