SECURITY APPARATUS, SECURITY METHOD, SECURITY PROGRAM, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To enhance the security against attacks from a third party while keeping the convenience in the key delivery system, the public key encryption system, and the digital signature system. SOLUTION: A security unit 20 uses a common polynomial a(x) with integer coefficients and r-sets of integers (s, q) to calculate a polynomial b(x)=Σn=0deg a(x)Σm=0r(qmsmn[partial differentiation operator]na(x)/n!)modI and transmits the arithmetic result to a security unit 30. The security unit 30 uses a common polynomial a(x) with integer coefficients and t-sets of integers (u,v) to calculate a polynomial c(x)=Σn=0deg a(x)Σm=0t(vmumn[partial differentiation operator]na(x)/n!)modI and transmits the arithmetic result to the security unit 20. Then the security unit 20 calculates a common key by using an expression of k(x)=Σn=0deg c(x)Σm=0r(qmsmn[partial differentiation operator]nc(x)/n!)modI, and the security unit 30 calculates the common key by using an expression of k(x)=Σn=0deg b(x)Σm=0t(vmumn[partial differentiation operator]nb(x)/n!)modI. COPYRIGHT: (C)2004,JPO