A method and apparatus for updating the password status of one or more servers in a client/server environment utilizes multiple passwords associated with a client process, including a current password and one or more non-current passwords. Each password has associated therewith a key and a key identifier....http://www.google.de/patents/US6094721?utm_source=gb-gplus-sharePatent US6094721 - Method and apparatus for password based authentication in a distributed system
