METHOD FOR PUBLISHING CERTIFICATION INFORMATION REPRESENTATIVE OF SELECTABLE SUBSETS OF RIGHTS AND APPARATUS AND PORTABLE DATA STORAGE MEDIA USED TO PRACTICE SAID METHOD

摘要

A method for certification by a plurality of certifying authorities of thepublickey of a user wishing to communicate using a public key encryption systemwhileasserting only a subset of rights. A plurality of certifying stations and auser stationexchange information and the user station derives a plurality of private keysfrom theexchanged information. The certifying stations also publish relatedinformation andtheir public keys. The user communicates using a private key formed by summingselected ones of said plurality of private keys corresponding to assertedrights. Athird party can derive the public key corresponding to the user's summedprivate keyby operating on the published information with a summation of the certifyingstationpublic keys.