METHOD OF ISSUANCE AND REVOCATION OF CERTIFICATES OF AUTHENTICITY USED IN PUBLIC KEY NETWORKS AND OTHER SYSTEMS

A technique for issuing and revoking user certificates of authenticity in a public key cryptography system, wherein certificates do not need expiration dates, and the inconvenience and overhead associated with routine certificate renewals are minimized or avoided entirely. A Certification Authority issues certificates as required, and issues a blacklist having a start date, an expiration date, and an entry for every invalid certificate issued after the start date. Users assume that every certificate issued prior to the blacklist start date is invalid, and that invalid certificates issued after the start date will be included in the current blacklist. A new blacklist is issued prior to expiration of the current one, and the blacklist start date is changed only when the blacklist becomes unmanageably long.