| 摘要 |
PURPOSE: A key generating method is provided to generate public-keys depending on the security of a non-linear simultaneous equation and rapidly decode a coded message with maintaining high security as well as transmit a signed message with a format of a coded message. CONSTITUTION: Public-keys provided from a combination expression generator(20) are stored in a public key memory(2) which anyone can access to. Secret-keys provided from an inverse transformation generator(30) are stored in a secrete-key memory(3) which only a user can access to. A reversible transformation generator(10) generates two reversible transformation expressions(A1,A2) having m factors as input/output and a quadratic non-linear reversible transformation expression(N). To this end, the reversible transformation generator(10) comprises generators(11) for two reversible transformation expressions(A1,A2) and one non-linear reversible transformation expression generator(12). Then, combination expressions(F=A2*N*A1) having m factors as input/output is calculated by combining the transformation expressions(A1,A2,N) as orders that the non-linear reversible transformation expression(N) is positioned between the reversible transformation expressions(A1,A2). The combination expressions(F=A2*N*A1) are provided together with a modular variable(n) as the public-keys used in coding a digital message(M) having m factors expressed with integers less than the modular variable(n).
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