Patent ID: 8132006
Filing Date: 2012-03-06
Classification: H04L

Abstract:
1. A computer-implemented cryptographic authentication method for at least one of first and second computer systems to prove knowledge of a predefined value π to the other one of the first and second computer systems in execution of a predefined authentication protocol, the value ir being one of a predefined set of values Π; the method comprising the first computer system performing the following operations in accordance with the authentication protocol: (1) receiving, over a computer network, data representing positive integer values N and x whose absolute values are greater than 1, wherein the authentication protocol requires the values N and x to be generated outside of the first computer system and to depend on the value π; wherein the authentication protocol requires each value in the set Π to be associated with a subset θ of a predefined set PP of positive integers, the subset θ consisting of one or more of the positive integers, different values in the set Π being associated with different subsets θ, wherein a product of all of the one or more integers in a subset θ associated with any one of the values in the set Π is different from a product of all of the one or more integers in a subset θ associated with any other one of the values in the set Π; wherein the authentication protocol requires the second computer system to know at least one of (i) the subset θ associated with the value π, (ii) a product P (2) generating data representing an integer e and an integer b, where b is coprime to N; (3) generating data which represent values y and z such that: y is congruent to x z is congruent to b (4) sending the data which represent the values y and z to the second computer system without sending, to the second computer system, data which represent any one or more of the values e, b, P (5) performing at least one of the following operations (5A) and (5B):