KEY SHARING DEVICE AND SYSTEM FOR CONFIGURATION THEREOF

摘要

A method of configuring a network device for key sharing and a method for a first network device to determine a shared key are provided. The method of configuring uses a private modulus ( p 1 ), a public modulus ( N ), and a bivariate polynomial ( f 1 ) having integer coefficients, the binary representation of the public modulus and the binary representation of the private modulus are the same in at least key length ( b ) consecutive bits. Local key material for a network device is generated by substituting an identity number into the bivariate polynomial and reducing modulo the private modulus the result of the substitution to obtain a univariate polynomial. Security may be increased by adding (440) one or more obfuscating numbers to coefficients of the univariate polynomial to obtain an obfuscated univariate polynomial. In a use phase, the network device determines a shared cryptographic key, by substituting (530) the identity number of another network device into the univariate polynomial and reducing modulo the public modulus and reducing modulo a key modulus.