A request for an access code for a locking mechanism is received; and a one-time use access code for the locking mechanism is subsequently issued. The one-time use access code may be issued from a list of currently available access codes for the locking mechanism in response to a request therefor, for...http://www.google.ca/patents/US6570488?utm_source=gb-gplus-sharePatent US6570488 - Locking mechanism for use with one-time access code
