Importance

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Abstract

A data transmitter capable of preventing illegal free reception of transmitted data by scrambling the same, and a data receiver adapted to descramble the received data properly despite any alteration of a scramble program. The data transmitter comprises a data source where predetermined data to be transmitted is stored; a circuit for generating a scramble program and control data; a circuit for scrambling the predetermined data in accordance with the scramble program; a circuit for generating a descramble program; and a circuit for transmitting the scrambled data, the descramble program and the control data to the data receiving terminal of each user or contractor. The control data includes a scramble key, and the scrambled data is transmitted via a satellite network or a CATV network, while the descramble program is transmitted via a telephone line. The data receiver is equipped with a circuit for descrambling the received data in accordance with the descramble program, and a circuit for compiling an intermediate code, which is included in the descramble program and is not dependent on any hardware, into a machine code.

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First Claim