CRYPTOGRAPHIC SYSTEM ALLOWING ENCRYPTED COMMUNICATION BETWEEN USERS WITH A SECURE MUTUAL CIPHER KEY DETERMINED WITHOUT USER INTERACTION

摘要

A secret key generator for a trusted authoritymeans in a cryptographic system comprising means forreceiving a publicly-known user identity IDA for a userA; and further comprising secret key generator meansfor transforming the publicly-known user identity ID Ainto secret key s A for the user A with the inverse ofthe exponentiation functiona s A ~ (ID A)2 (mod m),that is solved for s A, where a is a publicly-known baseparameter, where m is a publicly-known modulusparameter and m = p1 * P2 ~~~ * Pr, and where p1, P2,..., pr are secret system prime numbers. The inverse ofthe exponentiation function is infeasible to compute inorder to calculate the secret key s A without knowingthe prime numbers p1, p2, ..., Pr. The secret keys A enables user A to communicate securely to a user Bhaving publicly-known user identity ID B with a mutualsecure cipher key K AB, defined by the equation:K AB ~ (ID B) 2s A (mod m).The mutual secure cipher key K AB is determined withoutprevious interaction with the user B.