Commission information generator for making processes on communication performed by another computer

摘要

In a communicator in a communication system, a commission information generator for generating a commission parameter to make a process on a communication between communicators performed by another computer includes a first memory for storing a secret key and an encrypter for generating N number of the commission parameters, where N is a natural number, from a first to an N-th commission parameter. The encrypter regards a j-th shared key, where j is a positive integer equal to or less than N, out of the N number of shared keys as key information, encrypts a bit sequence representation of j-th partial information, associated with the j-th shared key, out of N pieces of partial information, and thereby generates a j-th commissioned parameter.

主权项

1. A commission information generator configured to generate encrypted commission parameters, comprising:
a first memory configured to store a given integer x, an integer number N of symmetric keys (key_1, key_2, . . . , key_N), and a public key P included in a given cyclic group of an order indicated by a term n; a decomposer configured to decompose the integer x stored in the first memory into N decomposed integers (x_1, x_2, . . . , x_N) included in an additive group () of integers; and a commission parameter generator configured to generate N encrypted commission parameters (P^(x_1), P^(x_2), . . . , P^(x_N)), wherein the decomposer reads out the given integer x from the first memory and decomposes it into the decomposed N integers included in the additive group () using the equality x=x_1+x_2+. . . +x_N(mod n), and outputs the N decomposed integers to the commission parameter generator, wherein the commission parameter generator picks a decomposed integer x_i (where i is a positive integer equal to or less than N) from the N decomposed integers output from the decomposer, and reads out the public key P from the first memory, performs a calculation using an operation (*) on the given cyclic group as an operator and the public key P as respective operands, and wherein the commission parameter generator further respectively encrypts the calculated commission parameter (P^(x_i)) using the symmetric key (key_i) corresponding to respective parameters.