Patent ID: 7111258

Claim:
A method for designing a logic circuit comprising the steps of: describing a register transfer level or operation level logic circuit through transmission and reception of information between a design site and a logic synthesis CAD program provider site; and generating a gate level logic circuit by using a logic synthesis CAD program, said logic synthesis CAD program performing the functions of: receiving said register transfer level or operation level logic circuit and generating said gate level logic circuit; outputting a characteristic of said generated gate level logic circuit as a report; encrypting the generated gate level logic circuit and outputting the encrypted gate level logic circuit; outputting a first encryption key corresponding to said gate level logic circuit; and receiving said encrypted gate level logic circuit and a second encryption key generated from said first encryption key, decrypting said encrypted gate level logic circuit, and outputting said gate level logic circuit, said design site receiving said logic synthesis CAD program at no charge from the logic synthesis CAD program provider site, referring to the circuit characteristic report on a logic circuit which is obtainable at the design site by receiving the register transfer level or operation level logic circuit and using said logic synthesis CAD program, and sending, if the circuit characteristic is as desired, said first encryption key to said logic synthesis CAD program provider site, said logic synthesis CAD program provider site generating a fee charged for the use of said logic synthesis CAD program by said design site based on the first encryption key sent from said designer site and sending, to said design site, said second encryption key obtained by processing said first encryption key, and said design site receiving said encrypted gate level logic circuit and said second encryption key and decrypting said encrypted gate level logic circuit by using said logic synthesis CAD program.