Patent ID: 6466668
Filing Date: 2002-10-15
Classification: G06F

Abstract:
An IC card, comprising:message receiving means for receiving a message from an input/output terminal by way of an input/output port; public key encryption processing means for performing elliptic curve public key encryption processing on said message; and output means for outputting result of the processing executed by said public key encryption processing means from the input/output terminal via the input/output port, wherein said public key encryption processing means comprises: multiple length arithmetic means for calculating through multiple length residual multiplication arithmetic values â€œABRâˆ’1 mod Nâ€ , â€œA2Râˆ’1 mod Nâ€ , and â€œARâˆ’1 mod Nâ€  representing, respectively, numerical values to undergo computation which make appearance in intermediate arithmetic processing for positive integers A, B, N and R. wherein A and B represent, respectively, variables which are given by input variables and/or interim variables, N represents a variable given as an input variable, and R represents a numerical value given as a constant; and computation means for performing multiplication and multiplicative inverse arithmetic on a finite group by using said multiple length arithmetic means, wherein said computation means includes multiplicative inverse arithmetic means for performing arithmetic operation represented by â€œkâˆ’1 mod nâ€  for a positive integer k which is relatively prime n by resorting to residual multiplication arithmetic represented by â€œk(nâˆ’2) mod nâ€  with the aid of said multiple length arithmetic means.